WO2016083691A1

WO2016083691A1 - Method for regenerating a particle filter and eliminating sulphur from a nitrogen oxide accumulator oxidation catalyst

Info

Publication number: WO2016083691A1
Application number: PCT/FR2015/052956
Authority: WO
Inventors: Pascal Folliot; Damien Lefebvre
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2014-11-24
Filing date: 2015-11-03
Publication date: 2016-06-02
Also published as: EP3224460A1

Abstract

The invention concerns a method for regenerating a particle filter and eliminating sulphur from an oxidation catalyst (DOC), the particle filter (FAP) and the oxidation catalyst (DOC) being housed in an exhaust line (4) provided on an internal combustion engine (1), into which an air/fuel mixture (M) is supplied. The method comprises: - a first enrichment step that is carried out when a phase of regenerating the particle filter (FAP) is triggered, in which a richness (R) of the air/fuel mixture (M) increases from a first richness (Ri) to a second richness (R2) - a second enrichment step in which the richness (R) increases from the second richness (R2) to a third richness (R3) that is carried out when an instruction to eliminate sulphur from the oxidation catalyst (DOC) is sent by a desulphation supervisor, and when an acceleration phase (Phaœ) of the motor vehicle is carried out.

Description

METHOD FOR REGENERATING A PARTICLE FILTER AND REMOVING SULFUR FROM AN OXIDATION CATALYST

NITROGEN OXIDE ACCUMULATOR.

The invention relates to a method of regeneration of a particulate filter and sulfur removal of a nitrogen oxide storage oxidation catalyst, the particulate filter and the accumulator oxidation catalyst nitrogen oxides being housed inside an exhaust line which is provided with an internal combustion engine of a motor vehicle within which an air / fuel mixture is introduced, the method comprising a first enrichment step which is carried out when a regeneration phase of the particulate filter is triggered during which a richness of the air / fuel mixture increases from a first wealth to a second wealth strictly greater than the first wealth.

The document FR 2,904,360 describes a method of regeneration of a particulate filter and sulfur removal of a nitrogen oxide storage catalyst NO _x . The method is implemented inside a downstream exhaust gas treatment plant that is emitted by an internal combustion engine fitted to a motor vehicle. According to this method, the temperature of the particulate filter is raised above an operating threshold temperature according to a first operating mode of the "particulate filter heating" type in order to regenerate the particulate filter, and the storage accumulator catalyst is heated. NO _x nitrogen oxides by increasing a coefficient of fuel richness and making it greater than 1 according to a second mode of operation of the type "storage catalyst heating NO _x " for the removal of sulfur from the catalyst oxidation accumulator d nitrogen, and the coefficient of fuel richness is adjusted by making it less than 1 according to a third following operating mode of the type "sulfur elimination catalyst accumulator NO _x ". In addition, according to the method, in the event of a regeneration request of the particulate filter or of the sulfur removal request of the NO _x nitrogen oxide storage catalyst, a combined total or partial regeneration of the filter is triggered at the same time. particulate and also sulfur removal of NO _x nitrogen oxide storage catalyst _. Such a process deserves to be improved so as to make the storage and oxidation functions of nitrogen oxides NO _x durable, despite the presence of sulfur compounds resulting from combustion of the diesel and a lubricant present. inside a combustion chamber of the internal combustion engine. An object of the present invention is to provide a method of regenerating a particulate filter and sulfur removal of oxidation nitrogen oxidation catalyst NO _x which is simple to implement. a fuel-efficient and yet efficient operation not only in terms of exhaust gas depollution produced by an internal combustion engine fitted to a motor vehicle, but also in a rapid, effective and controlled elimination of the sulfur present in the engine. inside the accumulator oxidation catalyst of nitrogen oxides NO _x.

A method of the present invention is a method of regenerating a particulate filter and removing sulfur from an oxidation catalyst nitrogen oxides accumulator. The particulate filter and the oxidation catalyst nitrogen oxides accumulator are housed inside an exhaust line which is provided with an internal combustion engine of a motor vehicle inside which is introduced an air / fuel mixture. The method comprises a first enrichment step which is carried out when a regeneration phase of the particulate filter is triggered during which a richness of the air / fuel mixture increases from a first richness to a second richness strictly greater than the first. wealth.

According to the present invention, the process comprises a second enrichment step during which the richness of the air / fuel mixture increases from the second richness to a third wealth strictly greater than the second richness. The second enrichment step is carried out when a sulfur removal instruction of the nitrogen oxide storage oxidation catalyst is sent by a desulphatation supervisor, and when an acceleration phase of the motor vehicle is performed. .

We understand the term supervisor according to its usual meaning in the field, particularly in the form of electronic / computer resources of the calculator type. By "removal" of sulfur, it is understood that the majority of the sulfur in the catalyst will be removed, or substantially all the sulfur, knowing that traces of sulfur may remain after this removal process.

According to a first embodiment, preferably, the sulfur removal instruction is given by the desulphatation supervisor when a temperature exceeds a threshold temperature. For example, the sulfur removal instruction is given by the desulfation supervisor when a first exhaust gas temperature produced by the internal combustion engine exceeds a first threshold temperature.

For example, the sulfur removal instruction is given by the desulphatation supervisor when a second temperature of the oxidation catalyst accumulating nitrogen oxides exceeds a second threshold temperature.

[001 1] Preferably, the sulfur removal instruction is given by the desulfation supervisor when a richness of an air / fuel mixture admitted inside a combustion chamber of a combustion engine internal of the motor vehicle exceeds a threshold wealth.

Preferably, the sulfur removal instruction is given by the desulphatation supervisor when an oxygen level upstream of the oxidation catalyst accumulating nitrogen oxides in a direction of circulation of the gases. Exhaust within the exhaust line is less than a threshold rate. Advantageously, the regeneration phase comprises indifferently a step of decreasing an amount of air admitted inside a combustion chamber of the internal combustion engine and / or a step of increasing a quantity fuel injected into the combustion chamber during a post-injection phase.

The method advantageously comprises a second stage of phase shift of injecting a fuel inside the combustion chamber with respect to an air loop.

The method advantageously comprises a third step of calculating first air loop instructions and in that the method advantageously comprises a fourth step of calculating second air loop instructions. The method advantageously comprises a first step of choosing an air loop setpoint chosen between the first setpoint and the second setpoint.

The method advantageously comprises a fifth step of calculating a third setpoint of a flow of air injected during a fuel injection post-injection inside the combustion chamber of the internal combustion engine. The method advantageously comprises a sixth step of calculating a richness adaptation which comprises a calculation of a fourth set of an admitted air flow inside the combustion chamber of the internal combustion engine.

The method advantageously comprises a second step of choosing a post-injection rate setpoint chosen between the third setpoint and the fourth setpoint.

According to another embodiment, preferably, the first enrichment step is a temperature regulation step of a fuel injection inside the internal combustion engine which comprises a first determination step by calculation. an exhaust gas temperature setpoint circulating inside the exhaust line, a second calculation step determining a pre-positioning of a quantity of fuel to be injected inside the exhaust line; a combustion chamber of the internal combustion engine to achieve the temperature setpoint, a third step of checking a saturation of the air / fuel mixture, a fourth step of measuring the first temperature of the exhaust gas upstream of the filter. particles in a direction of flow of the exhaust gases inside the exhaust line, and a fifth step of correction of the temperature setpoint in the first temperature of the exhaust gas.

Preferably, the second enrichment step advantageously comprises a sixth step of determining the third richness to allow desulfation of the oxidation catalyst nitrogen oxides accumulator.

The second enrichment step advantageously comprises a seventh stage of determining injection times of the air / fuel mixture inside the combustion chamber. The seventh determination step preferably comprises a measurement of an oxygen level upstream of the oxidation catalyst nitrogen oxides accumulator according to the direction of circulation of the exhaust gases inside the exhaust line.

The seventh determination step preferably comprises a determination of a threshold oxygen level below which injection of the air / fuel mixture to the third richness is allowed. The seventh determination step preferably comprises an estimate of a cumulative duration during which the second enrichment step is performed.

The seventh determination step preferably comprises a check of a combustion of soot inside a particle filter housed inside the exhaust line.

The second enrichment step advantageously comprises an eighth step of determining a total amount Qdesuifatation of fuel to be injected inside the combustion chamber to evacuate out of the oxidation catalyst nitrogen oxides accumulator the sulfur that it contains from the following relation [1]:

Qdesuifatation = (R3 ^x D _air / 14.5) - Q _∞ mb ^- Qreg [1]]

In which relation [1], R ₃ is the third richness, D _air is the _air flow at the exhaust, Q _CO mb is the fuel flow burned inside the combustion chamber and Q _reg is the fuel flow required for the first stage of enrichment. A motor vehicle for the implementation of such a method is mainly recognizable in that the motor vehicle is equipped with a nitrogen oxide storage oxidation catalyst, in particular of the passive NOx absorber type ( or "PNA" according to the acronym explained below).

Other features and advantages of the present invention will appear on reading the description which will be made of embodiments, in connection with the figures of the attached plates, in which:

Figure 1 is a schematic view of an internal combustion engine and an exhaust line of the present invention.

FIG. 2 is a diagrammatic view of a regeneration process of a particulate filter and sulfur removal of an oxidation nitrogen oxidation catalyst NO _x housed in the line of FIG. exhaust illustrated in the previous figure, according to a first embodiment.

Figure 3 is a drawing illustrating the richness curves of the air / fuel mixture from an implementation of the method illustrated in Figure 2, according to this first embodiment. FIG. 4 is a diagrammatic view of a regeneration process of a particulate filter and sulfur removal of an oxidation nitrogen oxidation catalyst NO _x housed in the line of FIG. exhaust illustrated in Figure 1, according to a second embodiment. In Figure 1, common to both embodiments, a motor vehicle is equipped with an internal combustion engine 1 to provide for its movement. The internal combustion engine 1 is in particular a diesel engine which is supplied with an air / fuel mixture M, comprising air and a fuel, such as diesel fuel. The internal combustion engine 1 emits exhaust gases 2 which are discharged to an external environment 3 to the motor vehicle via an exhaust line 4. The exhaust gases 2 contain pollutants, such as nitrogen oxides NO _x , unburnt hydrocarbons, particles or the like, which it is preferable to retain prior to a discharge to the external environment 3. To do this, the exhaust line 4 houses a treatment plant 5 Exhaust gas 2. The treatment plant 5 comprises successively in a direction of circulation 6 of the exhaust gas 2 from the internal combustion engine 1 to the external environment 3 an oxidation catalyst DOC oxide accumulator NO _x nitrogen which is adapted to retain unburnt hydrocarbons, to oxidize carbon monoxide to carbon dioxide but also to optimize a ratio N0 ₂ / NO _x, particularly at low temperature in order to optimize a r nitrogen oxides NO _x which the reduction is carried out by means of an SCR catalyst disposed downstream of the DOC catalyst oxidation of nitrogen oxides NO _x accumulator according to the direction of movement 6 of gases exhaust 2 inside the exhaust line 4.

The oxidation catalyst DOC NO _x nitrogen oxide accumulator is preferably a PNA type catalyst according to the acronym "Passive NO _x Absorber", for passive absorber of oxides of nitrogen. nitrogen NOx, which has a fairly low NO _x storage capacity and is targeted at a specific range of first temperature ΤΊ exhaust gas 2, which allows a natural desorption of nitrogen oxides NO _x beyond a certain first threshold temperature T _1sec | and which has a greater or lesser propensity to allow sulfur removal in a poor environment. At higher temperatures, the nitrogen oxides NO _x are naturally destocked at a richness R in conventional fuel. Sulfur which is much more stable is destocked more difficult hence the need for a richer air / fuel mixture M. However, the need for a rich air / fuel mixture M is less restrictive because a few seconds above a wealth R close to 1 are sufficient, that is to say between 1 and 1, 2, without the need to resort to a wealth regulation.

[0036] From unpreferably the DOC nitrogen oxide storage catalyst _NOx oxidation is likely to be an LNT catalyst or LNT Lite from the acronym of "Lean NO _x Trap ", for nitrogen oxides trap NO _x , which is characterized by a high storage capacity for NO _x , a need for exhaust gas with a greater R-richness that is to say significantly greater than 1, in particular greater than 1, 2, with a first temperature window Ti relatively limited to desorb and treat NO _x and a need for rich exhaust gas 2 to remove sulfur oxidation catalyst DOC oxide accumulator nitrogen NO _x .

The treatment plant 5 of the exhaust gas 2 also comprises a particulate filter FAP which is able to retain particles and / or soot prior to their discharge to the external environment 3. The particulate filter FAP tends to clog up as the particulate filter FAP retains impurities. To optimize a performance of the particulate filter FAP, it is known to regenerate the latter from an implementation of a regeneration mode of the particulate filter FAP which includes in particular an increase in the first temperature of the exhaust gas. 2. Such an increase in the first temperature of the exhaust gas 2 is obtained in particular from a fuel enrichment of the air / fuel mixture M admitted inside a combustion chamber 8 that includes the combustion engine internal 1, the richness R evolving from a first wealth Ri to a second wealth R ₂ , with the second wealth R ₂ which is strictly greater than the first wealth Ri.

The present invention aims in particular to optimize the oxidation and low temperature storage functions NO _x nitrogen oxides filled by oxidation catalyst DOC NO _x nitrogen oxide accumulator despite the presence of compounds sulfur compounds resulting from combustion of the diesel fuel and a lubricant present inside the combustion chamber 8, the sulfur-containing compounds tending to attach to the oxidation catalyst DOC accumulator of nitrogen oxides NO _x .

More particularly, the present invention proposes to take advantage of the regeneration mode of the particulate filter FAP and to increase the richness R in fuel of the air / fuel mixture M, for example during a vehicle acceleration phase. automobile, the wealth R evolving from the second wealth R ₂ to a third wealth R ₃ , with the third wealth R ₃ which is strictly greater than the second wealth R ₂ .

More particularly, the present invention is characterized by a forced non-alternation of rich / poor phases. Indeed, modifications of air loop and injection setpoint, which act on the richness R of the air / fuel mixture M, are implemented but only when the characteristics of the exhaust gases 2 are close to the necessary conditions. at a sulfur elimination, that is to say with a richness R of the air / fuel mixture M and a first temperature ΤΊ of the high exhaust gas. Such conditions are for example met in the acceleration mode of the motor vehicle.

[0041] In its generality, the present invention proposes to limit such a fixation of sulfur, sulfur removal from DOC oxidation catalyst accumulator of nitrogen oxides _NOx via combustion engine control strategy internal 1 which makes it possible to increase heat production inside the exhaust line 4 and to increase the richness R of the air / fuel mixture M over a threshold richness R _seu ii, in particular equal to at 1, 2, necessary for this elimination of sulfur. It follows that the third richness R ₃ is also higher wealth threshold R _Seui |.

The present invention consists in particular in taking advantage of a regeneration phase of the particulate filter FAP, during which the first temperature ΤΊ of the exhaust gas 2 is compatible with a sulfur removal from a point fuel enrichment of the air / fuel mixture M, during an acceleration phase of the motor vehicle where the richness R of the air / fuel mixture M is high.

The regeneration mode of the particulate filter FAP comprises a step of heating the particulate filter FAP which is obtained for example from a control of an air flow and / or supercharging pressure via an intake metering device and / or a turbocharger fitted to the motor vehicle, or from a control of a phasing and a fuel injection rate as well as an air pressure inside the vehicle; an intake rail which is provided with the internal combustion engine 1. The heating step is likely to comprise two types of heating, including a first heating from the internal combustion engine 1 and / or a second heating from the oxidation catalyst DOC nitrogen oxide accumulator NO _x . The first heating is for example obtained from a reduction of the air flow admitted inside the combustion chamber 8 and / or a sub-calibration of fuel injections or an addition of a post -injection close to an initial injection that induces an increase in an overall quantity of fuel admitted inside the combustion chamber 8. These provisions are such that an increase in the richness R of the air / fuel mixture M is obtained and that an increase in the temperature T of the exhaust gas 2 is reached downstream of oxidation catalyst DOC accumulator nitrogen oxides NO _x .

The second heating is for example obtained from a late fuel post-injection which does not allow combustion of the fuel inside the combustion chamber 8 but which is capable of generating exothermic reactions to the fuel. terminals of the battery DOC oxidation catalyst of nitrogen oxides NO _x from oxidation of unburnt hydrocarbons, such a post-injection being controlled in a closed loop via a specific control to obtain a first optimized ΤΊ temperature exhaust gas 2 downstream of the storage catalyst DOC oxidation of nitrogen oxides NO _x and upstream of the DPF particulate filter, depending on the direction of movement 6 of the exhaust gas 2 to the inside of the line exhaust 4.

In other words, the present invention proposes to enrich the exhaust gas 2 by further decreasing the amount of air admitted into the internal combustion engine 1 and / or by increasing the amount of fuel injected during the post-combustion period. late injection, this punctually during an acceleration phase Ph _aœ the motor vehicle.

Referring to FIG. 2, a method 100 of the present invention, according to a first embodiment, comprises a plurality of steps which are described below.

The method 100 comprises a first enrichment step 101 of fuel of the air / fuel mixture M. which is implemented when a regeneration phase of the particulate filter FAP is triggered. During the first enrichment step 101, the richness R of the air / fuel mixture M increases firstly from the first wealth Ri to the second wealth R ₂ , with the second wealth R ₂ which is strictly greater than the first wealth. Ri _. The method 100 comprises a second enrichment step 101 'of fuel of the air / fuel mixture M. which is implemented when an instruction INST of sulfur removal of oxidation catalyst DOC oxide accumulator nitrogen NO _x is addressed by a desulfation supervisor 7. In this case, the desulfation supervisor 7 addresses an order of enrichment of the exhaust gas 2 as soon as conditions are favorable. Finally, during the second enrichment step 101 ', the richness R of the air / fuel mixture M increases from the second richness R ₂ to the third richness R ₃ , with the third richness R ₃ which is strictly greater than the second wealth R ₂ . It is recalled at this stage of the description that the desulphatation supervisor 7 is a control means which controls the sulfur removal controls of the oxidation oxidation catalyst DOC NO _x nitrogen oxides. Said instruction INST of sulfur removal is more particularly addressed when the conditions below are independently or in combination together.

A first condition is for example favorable if the first temperature ΤΊ of the exhaust gas 2 at the output of the internal combustion engine 1, which can be measured or estimated, exceeds a first threshold temperature T _1seui |. A second condition is, for example, favorable if a second temperature T ₂ of the oxidation catalyst DOC NOx nitrogen oxide accumulator _, which can be measured or estimated downstream of the latter or ideally inside the oxidation catalyst DOC accumulator of nitrogen oxides NO _x, is greater than a threshold temperature T secondly _2SE uii- [0054] a third condition is for example favorable if the richness R of the exhaust gas is greater than 2 a threshold wealth R _seU ii.

For example, a fourth condition is favorable if an oxygen level X upstream of the oxidation catalyst DOC nitrogen oxides accumulator NO _x according to the direction of circulation 6 of the exhaust gases 2 inside. of the exhaust line 4 is less than a threshold rate X _seU ii, the oxygen level can be measured or estimated.

[0056] In other words, according to a preferred combination of the above conditions, when the second temperature T ₂ of the NO DOC nitrogen oxide storage catalyst oxidation _x reaches the second threshold temperature T _2seui | sulfur removal, and when the richness R of the air / fuel mixture M exceeds the threshold R-rich _Seui | then the enrichment of the air / fuel mixture M is operated. Conversely, when the richness R of the air / fuel mixture M falls below said threshold wealth _Seui R i or value close to this determined via a hysteresis, especially during a deceleration of the motor vehicle, the enrichment is then stopped. Fuel enrichment can also be stopped when the first temperature ΤΊ of the exhaust gas 2 at the outlet of the internal combustion engine 1 or the increase thereof exceeds a maximum calibratable threshold, or when the second temperature T ₂ the accumulator DOC oxidation catalyst of nitrogen oxides NO _x or the increase of the latter exceeds a maximum threshold calibrated or when the enrichment time exceeds a maximum threshold calibrated.

The method 100 includes a second stage of phase shift 102 of fuel injection inside the combustion chamber 8 with respect to an air loop. The injection phase shift is a temporal phase shift and not a phase shift of the injection compared to a top dead center. This second phase-shifting step 102 is optional and has the function of phase-shifting, if necessary, the action on a post-injection flow setpoint with respect to an action on the air loop. The significant inertia of the air loop compared to the injection is favorable because such inertia generates dynamic enrichment. However, it may be necessary in some cases to limit it.

The method 100 comprises a third calculation step 103 of first air loop instructions CONS1. During the third calculation step 103, the first air loop instructions CONS1 of the regeneration of the basic particle filter FAP are calculated such as an air flow set point, a boost pressure setpoint, a position setpoint of an intake metering and / or turbocharger, a regulation / piloting zone setpoint. These setpoints are calibrated in such a way as to obtain the optimum regeneration conditions of the particulate filter FAP.

The method 100 comprises a fourth calculation step 104 of second setpoints CONS2 air loop. Like the third calculation step 103 referred to above, the fourth calculation step 104 makes it possible to calculate the setpoints of the air loop of the enriched regeneration of the particulate filter FAP. Said instructions are calibrated in such a way as to obtain the highest possible richness. The order of magnitude of the decrease in air flow is about 10% to 20% depending on a motor operating point. This reduction of the air flow is obtained either by the intake metering device or by the position of a valve which limits the pressure of the exhaust gases 2 on a wheel of a turbine of a turbocharger in an internal combustion engine 1 which is supercharged or variable geometry of the turbocharger, either by the combination of the two. Since the adjustment of the injected flow rates and the adjustment of the injection timing are not modified with respect to the basic setting of the regeneration mode of the particulate filter FAP (excluding main injection and late injection), this increase in richness R is translated into an increase in the first temperature ΤΊ of the exhaust gas 2 at the outlet of the internal combustion engine 1 and / or an increase in the presence of other parameters, for example fumes. The maximum calibration criteria are maximized specifically for this setting. This situation is made possible because a period during which this adjustment is applied is not long enough to damage components of the internal combustion engine 1.

The method 100 then comprises a first CH1 choice step of a CONSAIR air loop setpoint chosen between the first setpoint CONS1 and the second setpoint CONS2. The method 100 comprises a fifth calculation step 105 of a downstream temperature of the oxidation catalyst DOC nitrogen oxides NO _x accumulator. The fifth calculation step 105 makes it possible to calculate a third setpoint CONS3 of a flow rate injected during the late post-injection, which makes it possible to reach the target temperature upstream of the particulate filter FAP in the direction of flow 6 of the exhaust gases. Exhaust 2 via exothermic reactions inside the oxidation catalyst DOC nitrogen oxides NO _x accumulator.

The method 100 comprises a sixth calculation step 106 of a richness adaptation. The sixth calculation step 106 comprises a calculation of a fourth setpoint CONS4 of a rate that must be injected in addition or possibly less in the late post-injection to achieve a desired setpoint value Rcons. This is an open-loop calculation of the post-late injection rate as a function of the intake air flow rate and the total flow rate injected into the combustion chamber. For a better precision, in the calculation of the richness R, the sixth calculation step 106 comprises a step of subtraction at the total flow of fuel injected from a part which is diluted in the oil, in other words a part which is not not received by the oxidation catalyst DOC nitrogen oxides NO _x accumulator. In order not to disturb the resumption of the temperature regulation at the end of the enrichment, the sixth calculation step 106 is functional during the enrichment with the post-injection flow actually injected. The method 100 then comprises a second selection step CH2 of a late post-injection rate setpoint CONSDEBIT chosen between the third setpoint CONS3 and the fourth setpoint CONS4. These provisions are such that the CONSDEBIT late post-injection rate setpoint is equal to the third setpoint CONS3 when the richness R is equal to the second richness R ₂ and the late post-injection rate setpoint CONSDEBIT is equal to the fourth setpoint CONS4 when the wealth R is equal to the third wealth R ₃ .

The implementation of the CONSAIR air loop setpoint and / or the CONSDEBIT late post-injection flow setpoint makes it possible to reach the third richness R ₃ . It will be understood by the term "step" actions that are undertaken concomitantly and not successively but which are described one after the other to clarify the disclosure of the invention. In other words, the first enrichment step 101, the second enrichment step 101 ', the second phase shift step 102, the third calculation step 103, the fourth calculation step 104, the first selection step CH1 the fifth calculation step 105, the sixth calculation step 106 and the second selection step CH2 are likely to take place at the same time.

In FIG. 3, the various richnesses R of the air / fuel mixture M are represented as a function of time, the second richness R _{2 of} which is the basic richness in the regeneration phase of the particulate filter FAP and the third R _3. which is obtained from the implementation of the method 100. In Figure 3, are also shown a speed of the motor vehicle through the first curve C1 and a late post-injection rate by the second curve C2.

In this example, the enrichment is triggered when the wealth R exceeds the threshold wealth R _seU ii which is 0.75. During this enrichment phase, the choice to a specific setting of the air loop from the air loop set point CONSAIR makes it possible to obtain the third richness R ₃ . In parallel, the application of the CONSDEBIT late post-injection flow setpoint allows to obtain the setpoint value Rcons.

These arrangements are such that the method is easily implemented to satisfy a need for increasing wealth R, advantageously comprising minor modifications of a control law of the internal combustion engine 1, a duration of limited point, no or little impact on engine approval, because based on an action on the air and a late post-injection flow, and no questioning of the model diesel dilution embedded if this denier takes into account the late postinjection rate.

FIG. 4 illustrates the second embodiment described below. Referring to FIG. 4, the method 100a of the present invention according to this second embodiment comprises a plurality of steps which are described below. .

The method 100a comprises a first enrichment step 101 a fuel of the air / fuel mixture M which is implemented when a regeneration phase of the particulate filter FAP is triggered. During the first enrichment step 101a, the richness R of the air / fuel mixture M increases firstly from the first richness Ri to the second richness R ₂ , with the second richness R ₂ which is strictly greater than the first wealth Ri _.

The method 100a comprises a second enrichment step 101 'has fuel of the air / fuel mixture M which is implemented when an inst instruction of sulfur removal of oxidation catalyst DOC oxide accumulator nitrogen NO _x is addressed by a desulfation supervisor 7. In this case, the desulfation supervisor 7 addresses an order of enrichment of the exhaust gas 2 as soon as conditions are favorable. Finally, during the second enrichment step 101 ', the richness R of the air / fuel mixture M increases from the second richness R ₂ to the third richness R ₃ , with the third richness R ₃ which is strictly greater than the second wealth R ₂ . It is recalled at this stage of the description that the desulphatation supervisor 7 is a control means which controls the sulfur removal controls of the oxidation oxidation catalyst DOC NO _x nitrogen oxides.

The first enrichment step 101 has fuel of the air / fuel mixture M comprises a first determination step 201 by calculation of a temperature set point Τ _∞Π5 of the exhaust gas 2 upstream of the particulate filter FAP according to the flow direction 6 of the exhaust gas 2 from the internal combustion engine 1 to the outside environment 3, to allow regeneration of the particulate filter FAP. The first enrichment step 101 has fuel of the air / fuel mixture M also comprises a second determination step 202 by calculating a prepositioning P of a quantity of fuel to be injected into the chamber of the fuel. combustion 8 to reach the temperature setpoint Τ _∞Π5 - The second determination step 202 is performed in an open loop situation, that is to say without a posteriori control. The second determination step 202 takes into account an exhaust air flow rate, a temperature of the exhaust gases 2 upstream of the DOC oxidation catalyst in the direction of circulation 6 of the exhaust gases 2 from the engine internal combustion 1 to the external environment 3, and a quantity of diesel fuel actually injected inside the combustion chamber 8.

The first fuel enrichment step 101 of the air / fuel mixture M then comprises a third verification step 203 of a saturation of the air / fuel mixture M. The third verification step 203 is performed indifferently on the first temperature ΤΊ of the exhaust gas 2 and / or the richness R of the air / fuel mixture M. The third verification step makes it possible to obtain the second richness R ₂ of the air / fuel mixture M to be injected inside the chamber In fact, the third verification step 203 makes it possible to modify the second richness R ₂ as a function of the first temperature ΤΊ of the exhaust gases 2 and / or as a function of an oxygen level X upstream of the oxidation catalyst DOC nitrogen oxides accumulator NO _x according to the flow direction 6 of the exhaust gases 2 inside the exhaust line 4.

The first enrichment step 101 has fuel of the air / fuel mixture M also comprises a fourth measurement step 204 of the first temperature ΤΊ of the exhaust gas 2 upstream of the particulate filter FAP.

The first enrichment step 101 has fuel of the air / fuel mixture M comprises a fifth correction step 205 of the temperature setpoint Τ _∞Π5 as a function of the first temperature ΤΊ of the exhaust gas 2 measured during the the fourth measurement step 204.

In other words, the first enrichment step 101a is a temperature control step of a fuel injection inside the internal combustion engine 1 to allow heating of the particulate filter FAP.

The second enrichment step 101 'comprises a sixth determination step 206 of the third richness R ₃ to allow desulphatation of the oxidation catalyst DOC nitrogen oxides NO _x accumulator. The second enrichment step 101 'a also comprises a seventh step of determining the moment of injection of the air / fuel mixture M inside the combustion chamber 8. The seventh determination step 207 comprises a measurement of the oxygen level X upstream of the oxidation catalyst DOC accumulator nitrogen oxides NO _x according to the direction of circulation 6 of the exhaust gas 2 inside the exhaust line 4 and a determination of a threshold rate X _under oxygen below which an injection of the air / fuel mixture M to the third richness R ₃ is authorized. The seventh determination step 207 also includes an estimate of a cumulative time during which the desulfation is performed and a verification that a soot combustion inside the particulate filter FAP is not disturbed.

[0080] The second enrichment step 101 'also includes an eighth step 208 of determining a total fuel quantity sulfation _of Q to be injected inside the combustion chamber 8 for discharging out of the oxidation catalyst DOC nitrogen oxides accumulator NO _x sulfur that the latter contains from the following relation [1]:

Qdesulfation = (¾ * Dair 14.5) - Q _CO mb ^- Qreg [1]

In which relation [1], D _air is the _air flow at the exhaust, Q _CO mb is the flow of fuel burned inside the combustion chamber 8 and Q _reg is the flow of fuel necessary for the first enrichment step 101 a. It will be understood by the term "step" actions that are undertaken concomitantly and not successively but which are described one after the other to clarify the disclosure of the invention. In other words, the first enrichment step 101 and the second enrichment step 101 'are performed simultaneously.

These arrangements are such that the method is easily implemented to satisfy a need for increasing wealth R, advantageously comprising minor modifications of a control law of the internal combustion engine 1, a duration of limited point and little or no impact on engine approval.

Claims

Process (100) for the regeneration of a particulate filter (DPF) and sulfur removal of an oxidation catalyst (DOC) nitrogen oxide accumulator (NO _x ), the particulate filter (DPF) and the oxidation catalyst (DOC) accumulator of nitrogen oxides being housed inside an exhaust line (4) which is provided with an internal combustion engine (1) of a motor vehicle with the inside which is introduced an air / fuel mixture (M), the method (100) comprising a first enrichment step (101) which is performed when a particle filter regeneration phase (DPF) is triggered during a richness (R) of the air / fuel mixture (M) increases from a first richness (Ri) to a second richness (R ₂ ) strictly greater than the first richness (Ri), characterized in that the process (100) comprises a second enrichment step (101 ') during which the richness (R) of the air / carburization mixture ant (M) increases from the second richness (R ₂ ) to a third richness (R ₃ ) strictly greater than the second richness (R ₂ ) which is achieved when a sulfur removal instruction (INST) of the catalyst of oxidation (DOC) nitrogen oxide accumulator is addressed by a desulfation supervisor (7), and when an acceleration phase (Ph _acc ) of the motor vehicle is performed.

Method (100) according to the preceding claim, characterized in that the sulfur removal instruction (INST) is given by the desulphatation supervisor (7) when a temperature (T) exceeds a threshold temperature (T _threshold) . ).

Process (100) according to any one of the preceding claims, characterized in that the sulfur removal instruction (INST) is given by the desulphatation supervisor (7) when a richness (R) of an air mixture fuel (M) admitted inside a combustion chamber (8) of an internal combustion engine (1) of the motor vehicle exceeds a threshold value (R _seU ii) -

Method (100) according to any one of the preceding claims, characterized in that the sulfur removal instruction (INST) is given by the desulphatation supervisor (7) when an oxygen level (X) upstream oxidation catalyst (DOC) accumulator of nitrogen oxides according to a direction of circulation (6) of the exhaust gas (2) inside the exhaust line (4) is less than a rate threshold (Xseuil).

5. Method (100) according to any one of the preceding claims, characterized in that the regeneration phase comprises indifferently a step of decreasing an amount of air admitted inside a combustion chamber (8) of the internal combustion engine (1) and / or a step of increasing an amount of fuel injected into the combustion chamber (8) during a post-injection phase.

6. Method (100) according to any one of the preceding claims, characterized in that the method (100) comprises a second step of phase shift (102) for injecting a fuel inside the combustion chamber ( 8) with respect to an air loop.

7. Method (100) according to any one of the preceding claims, characterized in that the method (100) comprises a third step of calculating (103) first setpoints (CONS1) air loop and that the method (100) comprises a fourth calculation step (104) of second setpoints (CONS2) of the air loop. 8. Method (100) according to any one of the preceding claims, characterized in that the method (100) comprises a fifth calculation step (105) of a third setpoint (CONS3) of a flow of air injected during a fuel injection post-injection inside the combustion chamber (8) of the internal combustion engine (1).

Method (100) according to claim 1, characterized in that the first enrichment step (101) is a temperature control step of a fuel injection inside the internal combustion engine (1) which comprises a first determining step (201) by calculating a temperature setpoint (Τ _∞Π5 ) of exhaust gas (2) flowing inside the exhaust line (4), a second determining step (202) ) by calculating a pre-positioning (P) of a quantity of fuel to be injected inside a combustion chamber (8) of the internal combustion engine (1) to reach the temperature setpoint (Τ _{∞ Π5} ), a third step of checking (203) a saturation of the air / fuel mixture (M), a fourth measuring step (204) of the first temperature (ΤΊ) of the exhaust gas (2) upstream of the particle filter (FAP) according to a direction of circulation (6) of the exhaust gases (2) to the inside of the exhaust line (4), and a fifth step of correcting (205) the temperature setpoint (T _cons ) as a function of the first temperature (ΤΊ) of the exhaust gases (2).

10. Process (100) according to claim 1 or 9, characterized in that the second enrichment step (101 ') comprises a sixth step of determining (206) the third richness (R ₃ ) to allow desulfation of the catalyst oxidation (DOC) nitrogen oxide accumulator (NO _x ). 11. Method (100) according to claim 9 or 10, characterized in that the second enrichment step (101 ') comprises a seventh step of determining (207) injection times of the air / fuel mixture (M) inside the combustion chamber (8).

12. Method (100) according to claim 1 1, characterized in that the seventh determination step (207) comprises a measurement of an oxygen level (X) upstream of the oxidation catalyst (DOC) accumulator. nitrogen oxides (NO _x ) according to the direction of circulation (6) of the exhaust gases (2) inside the exhaust line (4).

13. Process (100) according to any one of claims 1 1 and 12, characterized in that the seventh determination step (207) comprises a determination of a threshold rate (Xseuii) of oxygen below which a injection of the air / fuel mixture (M) to the third richness (R ₃ ) is allowed.

14. Method (100) according to any one of claims 1 1 to 13, characterized in that the seventh determination step (207) comprises an estimate of a cumulative duration during which the second enrichment step (101 ') is realized. 15. Method (100) according to any one of claims 1 1 to 14, characterized in that the seventh determination step (207) comprises a check of a combustion of soot inside a particulate filter ( FAP) housed inside the exhaust line (4).