BR102015029832A2 - METHOD FOR SCHEDULING THE REGENERATION OF A POOR MIXED NOX COLLECTOR - Google Patents

Abstract

"method for programming regeneration of a poorly mixed nox collector". It is a method of programming the regeneration of a poor mix nox collector 10, wherein the poor mix nox collector purge 10 is based on a need to minimize the emission of nox from an exhaust pipe 9. a vehicle 1. Using a schedule that purges the poorly mixed nox collector 10 more often each time, when it is only partially full, minimizes the risk of nox leakage and maximizes the nox collector's nox storage rate poor mix 10.

Description

(54) Title: METHOD FOR PROGRAMMING THE REGENERATION OF A POOR MIXED NOX COLLECTOR (51) Int. Cl .: F01N 3/01; F01N 9/00 (30) Unionist Priority: 12/04/2014 GB 1421560.2 (73) Holder (s): FORD GLOBAL

TECHNOLOGIES, LLC (72) Inventor (s): ANDRES AREVALO; KIM FORD; JAMES WRIGHT; ROMAIN DEMORY (74) Attorney (s): MARIA PIA CARVALHO GUERRA (57) Abstract: METHOD TO PROGRAM THE REGENERATION OF A POOR MIXED NOX COLLECTOR. This is a method of programming the regeneration of a poorly mixed NOx collector 10, in which the purge of the poorly mixed NOx collector 10 is based on a need to minimize the NOx emission from an exhaust pipe 9 of a vehicle 1. The use of a schedule that purges the poor mix NOx collector 10 more often each time, when it is only partially full, minimizes the risk of NOx leakage and maximizes the NOx storage rate of the NOx collector of lean mixture 10.

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Invention Patent Descriptive Report for: "METHOD FOR PROGRAMMING THE REGENERATION OF A POOR MIXED NOx COLLECTOR".

[001] The present invention relates to the regeneration of a lean mix NOx collector for a road vehicle engine and, in particular, to a method and apparatus for programming NOx purge from the poor mix NOx collector (LNT ) during the operation of the road vehicle.

[002] An LNT is an exhaust aftertreatment device for poor combustion engines. The LNT has to be purged periodically to release and convert the nitrogen oxides (NOx) stored in the LNT during poor engine operation. To complete the purge, the engine is operated on an air to fuel ratio that is rich in stoichiometry. As a result of the rich operation, substantial amounts of carbon monoxide (CO) and hydrocarbons (HC) are generated to convert the stored NOx. Typically, the purge mode is activated based on the estimated LNT load. That is, when the estimated NOx mass stored in the LNT exceeds a predetermined threshold, a transition to purge mode is initiated. The rich operation will continue for several seconds until the NOx is emptied from the LNT, after which, the purge mode is terminated and the normal poor engine operation is resumed.

[003] Since the engine must be operated in rich stoichiometry during the purge operation, the purge will have a significant negative effect on fuel economy compared to the fuel economy advantage of poor operation and thus is conventional practice optimize purging time to reduce loss in fuel economy.

[004] It is also known that, due to the fact that the regeneration of an LNT after-treatment device requires that the engine be operated in a rich manner, this will result in some mixture of fuel with the oil used to lubricate the engine, thereby resulting in oil dilution. Therefore, it is also common practice to delay the regeneration of an LNT until the level of

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NOx stored in the LNT reaches a predetermined high level, in order to maximize the amount of NOx stored in the LNT and reduce the number of regeneration cases that are needed, thereby reducing fuel dilution.

[005] The inventors have found that such prior art approaches are disadvantageous in the sense that the NOx leak from an LNT increases as the LNT is filled with NOx. When an LNT is substantially empty of stored NOx, even large variations in engine operation, such as sudden demands for increased torque, will not result in any significant NOx leakage from the LNT. However, when the LNT fills with NOx, the LNT's resistance to NOx leakage is reduced, and thus, as the filling approaches a level close to that at which regeneration is conventionally initiated, even relatively small variations in engine operation can result in significant NOx leakage from an LNT.

[006] Any leakage of NOx from an LNT will result in a peak in vehicle NOx emissions and this is undesirable. In addition, the instant increase in NOx emissions due to the peak of NOx will also have a detrimental effect on the vehicle's cumulative NOx emissions.

[007] With progressively more stringent emission targets, particularly for NOx, any increase in cumulative NOx emissions can result in the verification that a vehicle is not in compliance due to the leakage of NOx, although during normal vehicle execution, the level exhaust pipe NOx is well within the permitted legislative levels.

[008] An example of more stringent emission regulations in Europe is the introduction of the Real Driving Emissions (RDE) requirement to report emissions using a Portable Emission System (PEMS) )) in real driving conditions on public roads.

3/17 [009] It is an objective of the invention to provide a method of programming the regeneration of a poorly mixed NOx collector that minimizes exhaust pipe NOx emissions.

[010] According to a first aspect of the invention, a method of programming the regeneration of a poorly mixed NOx collector arranged to receive exhaust gas from a poor combustion engine of a vehicle is provided, the method comprising the use of at least one purge schedule to schedule regeneration of the poor mix NOx collector where, when a parameter indicative of one of the aging of the poor mix NOx collector and an emission factor is above a predefined level, a first purge schedule is used to purge the lean mix NOx collector, the first purge schedule being based on a relationship between exhaust pipe NOx emissions and one of the engine run times between purging and the distance traveled between purging cases, to predict one of the engine run times and a distance traveled between purging cases, which will result in a minimum amount of NOx of scape that is produced by the engine and the purge of the NOx collector of poor mix in one of the expected engine run time and the predicted distance traveled, in order to minimize exhaust pipe NOx emissions produced by the engine and, when the parameter indicative of one of the aging of the poor mix NOx collector and the emission factor is below the predefined level, a second purge schedule is used to purge the poor mix NOx collector, with the second purge schedule minimizing a conversion ratio of NOx compared to CO2 produced by the engine.

[011] The method may further comprise the generation of a lean mix NOx collector storage model and the use of the lean mix NOx collector storage model to predict when a NOx leak will occur for use in minimizing

4/17 exhaust pipe NOx emissions.

[012] The low mix NOx collector storage model can provide an estimate of NOx stored in the low mix NOx collector as a function of the modeled low mix NOx collector temperature and exhaust gas flow rate modeled. Alternatively, the low mix NOx collector storage model can provide an estimate of the NOx stored in the low mix NOx collector based on a NOx measurement entering the low mix NOx collector and the flow rate modeled exhaust gas.

[013] Alternatively, the method may further comprise the use of a NOx sensor located upstream of the poorly mixed NOx collector and a NOx sensor located downstream of the poorly mixed NOx collector to measure NOx directly , and the use of NOx sensor measurements downstream and upstream to predict when NOx leakage will occur for use in minimizing exhaust pipe NOx emissions. [014] The method may further comprise the use of a NOx sensor located downstream of the poorly mixed NOx collector to directly measure NOx, and the use of the downstream NOx sensor measurement to provide a leakage measurement of Direct NOx for use in scheduling a purge to minimize exhaust pipe NOx emissions.

[015] A passive selective catalyst can be located downstream of the lean mix NOx collector and the first purge schedule can be selectively modified to maximize NH3 production for use by a passive selective redundant catalyst downstream.

[016] In accordance with a second aspect of the invention, an electronic system is provided to program the purge of a poorly mixed NOx collector willing to receive exhaust gas from a poor combustion engine, the electronic system being operable for generate at least one purge schedule to schedule the purge of the mixing NOx collector

5/17 poor where, when a parameter indicative of one of the aging of the poorly mixed NOx collector and an emission factor is above a predefined level, the electronics are operable to generate and use a first purge schedule with based on a relationship between exhaust pipe NOx emissions and one of the engine run time between purging cases and the distance traveled between purging cases, to predict one of the engine run time and a distance traveled between the purging cases that will result in a minimum amount of exhaust pipe NOx that is produced by the engine, and the electronics are additionally operable for using the first purge schedule to purge the poorly mixed NOx collector in one of the expected engine run time and the predicted distance traveled in order to minimize the amount of exhaust pipe NOx emissions produced by the engine and, when the parameter indicating one of the age the poorly mixed NOx collector and the emission factor is below the preset level, the electronics are operable to generate and use a second purge schedule to minimize a NOx ratio produced by the engine compared to the CO2 produced by the engine .

[017] The electronics can include a central processor, and the central processor can be operable to generate the first purge schedule.

[018] The central processor can be operable to control the engine for purging the lean mix NOx collector in accordance with the first purge schedule.

[019] The electronics can include a central processor, and the central processor can be operable to generate the second purge schedule.

[020] The electronics may include a central processor, and the central processor may be operable to control the engine for purging the poor mix NOx collector in accordance with the second

6/17 purge schedule.

[021] The invention will now be described by way of example with reference to the accompanying drawings, in which:

[022] Figure 1 is a schematic plan view of a motor vehicle, according to a third aspect of the invention, which has a system for programming the regeneration of an LNT in accordance with a second aspect of the invention;

[023] Figure 2 is a block diagram of the system shown in Figure 1 that shows in more detail various functional components of the system;

[024] Figure 3 is a schematic diagram of a first modality of an exhaust system for an engine;

[025] Figure 4 is a schematic diagram of a second mode of an exhaust system for an engine; and [026] Figure 5 is a graph showing the relationships between CO2, fuel in oil, exhaust pipe NOx including purge and a NOx reduction ratio for CO2 ratio versus purge distance.

[027] With particular reference to Figures 1 and 2, a motor vehicle 1 is shown that has a poor combustion engine in the form of a diesel engine 2. Motor vehicle 1 has, in this case, four road wheels 5, 6 of which the two front road wheels 5 are driven by the engine 2 via a transmission line 3 which includes a transmission for multiple reasons, a differential and a pair of axles. A direction of travel to the front of the motor vehicle 1 is indicated by the arrow F in Figure 1.

[028] Engine 2 is connected to an exhaust system 7 through an exhaust manifold 8 which, although not shown, can include a turbocharger. The exhaust gas flows from the engine 2 through the collector tube 8 to the exhaust system 7 and passes through a poorly mixed NOx (LNT) collector 10, a passive selective catalytic reduction (pSCR) catalyst 11 and a muffler 12 before going out into the atmosphere through

7/17 an exhaust pipe 9. It will be verified that the exhaust system 8 may include additional exhaust after-treatment devices or more than one muffler, and then it is not limited to the exact configuration shown in Figure 1.

[029] An electronic system 20 is provided to control the operation of motor 2 and to program the regeneration or purge of the LNT 10.

[030] The electronic system 20 comprises a central processor 21 arranged to receive an admission 22 indicative of the nature of the exhaust gas that passes through the exhaust system 7 of one or more exhaust gas sensors and an admission 23 indicative of the operation of the engine 2 and / or vehicle 1.

[031] The central processor 21 comprises, in this case, a central processor unit with the capacity to execute a computer program and several memory devices, in which one or more programs and operational instructions for the central processor unit are stored.

[032] The central processor 21, and in particular the central processor unit, is arranged to process the signals received from inputs 22, 23 and provide an emission for an engine control unit 25 used to control the operation of the engine 2 .

[033] With regard to the present invention, the electronic system 20 works in order to program the regeneration of the LNT 10 in accordance with a method of programming the regeneration of a poorly mixed NOx collector as provided by the present invention. It will be seen, however, that the electronics 20 and, in particular, the motor control unit 25 can also be operable to control the operation of the motor 2 during the normal running of the motor 2.

[034] With reference to Figures 3 and 4, two modalities of the invention are shown, in particular, the various sensors that form the intake 22 of Figure 2 together with one of the sensors that form the intake 23 of Figure 2. [035] With reference to Figure 3, the exhaust system 7 is shown in

8/17 more details. The central processor 21 is connected to several exhaust gas sensors that form the intake 22. The exhaust gas sensors, in this case, comprise an air to fuel ratio sensor or lambda sensor 22a, a first gas temperature sensor exhaust 22c, a second exhaust gas temperature sensor 22d and a third exhaust gas temperature sensor 22e.

[036] A single mass airflow (MAF) sensor 23a is shown in Figure 3 as a constituent of the intake 23, however, it will be seen that several other sensors can be included as part of the intake 23 such as, for example, and without limitation, an engine speed sensor, an accelerator position sensor, a vehicle speed sensor, a vehicle distance sensor and a sensor or other means to provide an indication of fuel consumption.

[037] The operation of the electronic system 20 is as follows. A measurement of the air mass flow is provided by the MAF sensor 23a, a value of the ratio of air to fuel from the exhaust leaving engine 2 is provided by the lambda sensor 22a, and the first and second gas temperature sensors of exhaust 22c and 22d provide exhaust gas temperature values upstream and downstream of the LNT 10. The use of the sensor inlets 22a, 22c, 22d and 23a allows the central processor 21 to calculate the NOx outside the engine and also the storage of that NOx inside the LNT.

[038] Modeled feed gas NOx admissions produced using admissions 22 and 23 are supplied to an LNT storage model. The LNT storage model provides an estimate of NOx stored in LNT 10 as a function of modeled LNT temperature and modeled gas flow rate. The modeled LNT storage is then used to predict when the NOx leak will occur due to a low LNT 10 storage rate.

[039] This storage rate information is then used to schedule an LNT purge to return LNT 10 to a

9/17 low NOx leakage and high storage rate. The LNT 10 NOx leak forecast is used to trigger an early LNT 10 purge and, therefore, reduce the NOx flow rate. The ideal LNT 10 conversion point is also modeled to guide the purge schedule to a maximum NOx efficiency or maximum NOx conversion. The stored NOx conversion efficiency is modeled as a function of the modeled LNT temperature, modeled gas flow rate, modeled NOx storage and lambda during purging.

[040] In the event that a passive SCR downstream 11 is present in the exhaust system 7, the purge schedule can also be modified to maximize the production of NH3 at the expense of CO2 in order to improve the conversion of NOx to the passive SCR 11 that uses NH3 as a reducer.

[041] Modeled conversion efficiency can also be used to guide the placement of LNT purges for maximum conversion of stored NOx to a minimum fuel / CO2 penalty.

[042] The fuel economy mapped by LNT purging can also be used to trigger LNT purges to minimize the fuel / CO2 penalty.

[043] In some embodiments, the electronic system 20 is operable for the use of more than one purge schedule depending on the status of the LNT 10 or other requirements such as emission regulations.

[044] In such a case, a first purge schedule is used to guide the purge of the LNT 10 in order to minimize 0 exhaust pipe NOx, and a second purge schedule is used to minimize a NOx conversion ratio in comparison with the CO2 produced.

[045] It will be verified that there are several emission regulations that have to be complied with and that, in some cases, in order to comply with such regulations, it is necessary to direct the purge of the LNT 10 to minimize the exhaust pipe NOx. For example, there may be a requirement to limit the mass of NOx per km traveled to a predefined level. Euro emission standards

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6, for example, require less than 0.08 g / km of NOx emissions for diesel cars and less than 0.06 g / km of NOx emissions for gasoline cars. Therefore, if NOx emissions are greater than an Ef emission factor equal to the actual NOx emission from the vehicle divided by the NOx emissions allowed by the regulation, which means Et> 1.0, then the emission regulations will not are being fulfilled. Therefore, in order to avoid this, a predefined level for the emission factor such as, for example, 0.85, can be established and, if Ef> 0.85, the first purge schedule is used and, if Ef < 0.85, the second purge schedule is used.

[046] Similarly, in relation to the requirement for Real Driving Emissions in Europe, a compliance factor between the reality in road emissions and the limits defined for the regulated New European Driving Cycle (NEDC) must be calculated, and this must be less than a limit to be declared, if the use of the vehicle indicates that the expected value of the emission factor with the use of the second programming is above the factor, or some limit below the factor, then the first schedule can be used.

[047] However, in circumstances in which a vehicle's NOx emissions are well within any required regulations, it is preferable to use the second schedule due to the fact that it optimizes the fuel / CO2 penalty, since this schedule not only it will reduce the costs of running a vehicle, but it will also reduce the dilution of fuel in oil.

[048] It should also be noted that as an LNT ages, its storage efficiency will decline compared to a new LNT. Therefore, when the LNT is new, there may be the possibility of using a purge schedule such as the second purge schedule, due to the fact that there is no risk that any risk of tailpipe emissions exceeds the prescribed limits, but as the LNT ages, the LNT becomes unable to comply with such regulations unless the

11/17 first purge schedule is used. Therefore, by establishing a parameter such as an equivalent aging indicative of a predicted thermal aging of the LNT and by setting an aging limit, it is possible to switch from the second purge schedule to the first purge schedule based on whether the value current parameter is above the limit or below the limit. For example, if the equivalent aging is greater than the aging limit, then the first purge schedule is used and, otherwise, the second purge schedule is used.

[049] With reference to Figure 4, an alternative modality is shown to that shown in Figure 3 which, in most cases, is the same as the first modality.

[050] The central processor 21 is, as before, connected to several exhaust gas sensors that form the intake 22, but in this case, in addition to the air to fuel ratio sensor or lambda sensor 22a, from the first temperature sensor of exhaust gas 22c, the second exhaust gas temperature sensor 22d and the third exhaust gas temperature sensor 22e, a first NOx sensor 22b located upstream of LNT 10, and a second NOx sensor 22f are also provided located downstream of passive SCR 11, in order to directly detect NOx emissions from the exhaust pipe 9.

[051] As before, a single mass airflow (MAF) sensor 23a is shown in Figure 4 as constituting the intake 23, however, it will be seen that several other sensors can be included as part of the intake 23 such as, for example, and without limitation, an engine speed sensor, an accelerator position sensor, a vehicle speed sensor, a vehicle distance sensor and a sensor or other means to provide an indicative emission of spent fuel.

[052] The operation of the electronic system 20 is as follows. A measurement

12/17 of the mass air flow is provided by the MAF sensor 23a, a value of the ratio of air to exhaust fuel leaving engine 2 is provided by the lambda sensor 22a and the first and second gas temperature sensors of exhaust 22c and 22d provide exhaust gas temperature values upstream and downstream of the LNT 10. The use of the admissions of these sensors 22a, 22c, 22d and 23a allows the central processor 21 to calculate the NOx outside the engine and also the storage of that NOx inside the LNT.

[053] The upstream NOx sensor 22b provides a direct NOx measurement for the LNT 10 and thus a NOx feed gas model is not required.

[054] The exhaust pipe NOx sensor 22f is used in this case to provide, together with the upstream NOx sensor 22b, a direct measurement of the NOx stored in the LNT 10 without the need to model it. It will be verified that the NOx stored in LNT 10 is the difference between the NOx measured by the NOx sensor 22b that enters the LNT 10 and the NOx measured by the NOx sensor 22f that leaves the exhaust pipe 9 in case there is no passive SCR 11a downstream of LNT 10.

[055] This means that: [056] NOx storage of LNT = exhaust gas NOx - exhaust pipe NOx.

[057] In a case in which there is a passive SCR 11, as shown in Figure 4, between the exhaust pipe NOx sensors and upstream 22b and 22f, then the NOx stored in LNT 10 is the difference between the measured NOx by the NOx 22b sensor that enters the LNT 10 and the NOx measured by the NOx 22e sensor that leaves the exhaust pipe 9 minus the NOx removed by the passive SCR. [058] Therefore, in the case where there is a passive SCR downstream of the LNT: [059] NOx storage of LNT = [(Exhaust gas NOx - NOx removed in the passive SCR) - Exhaust pipe NOx], [060] Passive SCR NOx reduction can be modeled.

13/17 [Οθ1] In addition, the exhaust pipe NOx sensor 22f can also be used to provide a direct measurement of NOx leakage, and this can be used to trigger a purge from the LNT 10.

[062] Using the second modality shown in Figure 4, the robustness of the programming can be accentuated because of the use of exhaust pipe NOx sensors and upstream 22b, 22f that provide real measurements of NOx entering LNT 10 and the leakage of NOx from LNT 10 instead of using predictions based on system models.

[063] As before, the ideal conversion point for LNT 10 can be modeled to guide the purge schedule to a point of maximum NOx efficiency or maximum NOx conversion. The stored NOx conversion efficiency can be modeled as a function of the measured LNT temperature, gas flow rate of the MAF sensor 23a, calculated NOx storage of the NOx sensors 22b and 22f and the air to fuel ratio measured by the lambda sensor 22a during a purge.

[064] As before, when a passive downstream SCR 11 is present in the exhaust system 7, a purge schedule can also be modified to maximize the production of NH3 at the expense of CO2 in order to improve the conversion of NOx into the SCR passive 11 that uses NH3 as a reducer. [065] As before, conversion efficiency can also be used to guide the placement of LNT purges aiming at maximum conversion of stored NOx for a minimum fuel / CO2 penalty.

[066] As before, fuel consumption mapped by LNT purging can also be used to trigger LNT purges to minimize the fuel / CO2 penalty.

[067] The electronic system 20 can, as mentioned before, be operable for the use of more than one different purge schedule.

[068] For example, there may be a first purge schedule to guide the purge of the LNT 10 to minimize 0 exhaust pipe NOx; a second purge schedule to guide the purge of the LNT 10 to

14/17 minimize a conversion rate from NOx to CO2 penalty and a third purge schedule to modify the purge schedule to maximize the production of NH3 at the expense of CO2.

[069] With reference to Figure 5, examples of key relationships are shown in relation to the distance traveled by a vehicle between the cases of LNT regeneration / LNT purging (DeNOx).

[070] It will be verified that, instead of the distance traveled between the purging cases, the key relationships can be mentioned against the engine run time between the purges.

[071] The first ratio is that of CO2 in relation to the distance between purging cases, and the second is a relationship between the amount of fuel transferred to the engine oil in relation to the distance between purging cases. Due to the fact that these two relations have a similar characteristic, they are shown as a single curve, although the actual values are evidently different.

[072] It can be seen that, as the distance between purging cases increases, the amount of CO2 and fuel in oil decreases. This is not surprising due to the fact that both CO2 and fuel in oil are related to the additional fuel used to purge the LNT through rich engine operation (Lambda <1). Therefore, if the only requirement is to reduce the fuel in oil or CO2, it would be desirable to increase the distance between purging cases to the maximum possible distance.

[073] The third relationship is between the exhaust pipe NOx including the purge effect and the distance traveled between the purge cases. The curve has a substantially U shape that has a minimum value indicated by an 'a' arrow. The ‘a’ point corresponds to the distance used for the first purge schedule.

[074] For the distances between purging cases below the ideal 'a' point, the amount of exhaust pipe NOx increases as the distance decreases, due to the effect of the increased frequency of purging cases

15/17 and the negative effect that this has on the exhaust pipe NOx because of the rich run (Lambda <1) of the engine during a purge.

[075] For distances greater than the ideal 'a' point, the amount of exhaust pipe NOx increases as the distance increases, due to the increased NOx leakage effect in conjunction with the NOx produced by the purge case , both of which adversely affect exhaust pipe NOx.

[076] The fourth relationship is a G ratio between NOx reduction and CO2 production in relation to the distance traveled between purging cases. [077] In this case, the ratio drops as the distance traveled between purging cases increases, until a distance indicated by an arrow 'b' is at a minimum. From the minimum 'b' point, it starts to increase again as the distance between purging cases is further increased, due to the fact that the NOx leak is having an adverse effect on the reduction of NOx, and due to the fact that the effect of this NOx leak is so significant that it overlaps the decreasing level of CO2, as the distance between purging cases is increased. The ‘b’ point represents a minimal fuel / CO2 penalty approach for LNT purge scheduling, so that purge is initiated when the G ratio is at a minimum.

[078] Exhaust pipe NOx = Function (FG NOx + NOxsiip + NOx _P ur _ge + NOXconv%) [079] Where: [080] FG NOx = NOx of feed gas [081] NOxslip = NOx due to leakage ;

[082] NOxpurge = NOx due to purging; and [083] NOxconv% = NOx due to the conversion efficiency of LNT.

[084] If the method includes more than one purge schedule, point 'b' corresponds to the distance used for the second purge schedule, and the method switches between purge at point 'a' and purge at point 'b' , as

16/17 previously described.

[085] However, from Figure 5, it can be seen that if the purge is delayed until this distance has been covered since the last purge case, then the exhaust pipe NOx level taking into account any purging and NOx leakage cases will be considerably higher than the ideal 'a' point, as indicated in Figure 5, by point P.

[086] Therefore, the inventors have found that, with increasingly expensive NOx targets, a method that optimizes exhaust pipe NOx, as indicated by the 'a' point, will allow a vehicle that would not meet a legislative limit to do it. For example, if the exhaust pipe NOx level that must be maintained to comply with a legislative limit is set at an L level, a vehicle that uses the method proposed by the present invention would pass, whereas the same vehicle optimized for the reason C would not pass, due to the fact that point P is above the limit 'L'. [087] Therefore, in summary, the conventional diesel LNT control strategy is based on feed gas NOx, LNT storage, reduction of NOx in LNT and minimization of fuel purging penalty. This requires the use of a large percentage of the LNT's storage capacity in order to reduce the number of purges and the cost of these purges. The consequence of this strategy is that the LNT tends to be filled to a high percentage of its capacity, in the order of 90 to 100%, and this will increase the rate and occurrence of NOx leak, release or flow due to changes in flow and temperature exhaust gas. In other words, the exhaust pipe NOx emission is not minimized due to LNT leakage or NOx flow. Using a method as proposed by the present invention, purges are not programmed as with prior art systems when the LNT is practically full, but are instead programmed to produce minimal exhaust pipe NOx. This is achieved by increasing the purging frequency (reducing the distance between purging cases) in order to trigger purges when the LNT is

17/17 only partially filled. Such an approach maximizes the LNT storage rate and virtually eliminates any risk of NOx leakage from the LNT.

[088] It will be verified by those skilled in the art that the invention has been described by way of example, with reference to one or more modalities, and that it is not limited to those disclosed modalities, it is only limited by the scope of the invention as defined by the appended claims .

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Claims (15)

1. Method of programming the regeneration of a poorly mixed NOx collector willing to receive exhaust gas from a poor combustion engine in a vehicle, the method being characterized by understanding the use of at least one purge schedule to program regeneration of the poor mix NOx collector in which, when a parameter indicating one of the aging of the poor mix NOx collector and an emission factor is above a predefined level, a first purge schedule is used to purge the poorly mixed NOx collector, the first purge schedule being based on a relationship between exhaust pipe NOx emissions and one between engine run time between purge cases and the distance traveled between purge cases , to predict one of the engine run times and the distance traveled between purging cases that will result in a minimum amount of exhaust pipe NOx that produced by the engine and purging the poorly mixed NOx collector in one of the expected engine run time and the predicted distance traveled in order to minimize NOx emissions from the exhaust pipe produced by the engine and, when the parameter indicating a among the aging of the poor mix NOx collector and the emission factor is below the predefined level, a second purge schedule is used to purge the poor mix NOx collector, with the second purge schedule minimizing a conversion ratio NOx compared to CO2 produced by the engine. 2. Method according to claim 1, wherein the method is characterized in that it further comprises generating a poorly mixed NOx collector storage model and using the poorly mixed NOx collector storage model to predict when the leak NOx will occur for use in minimizing exhaust pipe NOx emissions. 3. Method according to claim 2, characterized in that the 2/4 poor mix NOx collector storage model provide an estimate of NOx stored in the poor mix NOx collector as a function of modeled poor mix NOx collector temperature and modeled exhaust gas flow rate. 4. Method according to claim 2, characterized in that the lean mix NOx collector storage model provides an estimate of the NOx stored in the lean mix NOx collector based on a NOx measurement entering the NOx collector lean mixture and modeled exhaust gas flow rate. 5. Method, according to claim 1, wherein the method is characterized by further comprising the use of a NOx sensor located upstream of the NOx collector of poor mix and a NOx sensor located downstream of the NOx collector of lean mixture to measure NOx directly and the use of NOx sensor measurements downstream and upstream to predict when NOx leakage will occur for use in minimizing tailpipe NOx emissions. 6. Method according to claim 1, wherein the method is characterized by further comprising the use of a NOx sensor located downstream of the poorly mixed NOx collector to measure NOx directly and the use of sensor measurement downstream NOx to provide a direct NOx leak measurement for use in scheduling a purge to minimize exhaust pipe NOx emissions. 7. Method according to claim 1, characterized in that a passive selective catalyst is located downstream of the poorly mixed NOx collector, and the first purge schedule is selectively modified to maximize the production of NHs for use by a passive selective redundant catalyst downstream. 8. Electronic system to program the purge of a poorly mixed NOx collector that is willing to receive exhaust gas from a poor combustion engine, the electronic system being characterized by being 3/4 operable to generate at least one purge schedule to schedule the purge NOx collector purge where, when a parameter indicative of one of the poorly mixed NOx collector aging and an emission factor is above At a predefined level, the electronics are operable to generate and use a first purge schedule based on a relationship between exhaust pipe NOx emissions and one among the engine run time between purge cases and the distance traveled between purging cases, to predict one of the engine's runtime and a distance traveled between purging cases that will result in a minimum amount of exhaust pipe NOx that is produced by the engine, and the electronics is additionally operable for the use of the first purge schedule to purge the lean mix NOx collector in one of the predicted engine run time and the predicted distance traveled in order to minimize the amount of tailpipe NOx emissions produced by the engine and, when the parameter indicating one of the aging of the poorly mixed NOx collector and the emission factor is below the predefined level, the electronics are operable for generate and use a second purge schedule to minimize a ratio of NOx produced by the engine compared to CO2 produced by the engine. 9. System according to claim 8, in which the electronic system is characterized by including a central processor and the central processor is operable to generate the first purge schedule. 10. The system according to claim 8, wherein the electronic system is characterized by including a central processor, and the central processor is operable to control the engine to purge the NOx collector of poor mix according to the first programming of purge. 11. The system of claim 8, wherein the electronic system is characterized by including a central processor, and the central processor is operable to generate the second purge schedule. 12. System according to claim 8, in which the system Electronic 4/4 is characterized by including a central processor, and the central processor is operable to control the engine to purge the low mix NOx collector in accordance with the second purge schedule. 13. Method of programming the regeneration of a lean mix NOx collector characterized by being willing to receive exhaust gas from a poor combustion engine of a vehicle, substantially as described in this document, with reference to the attached drawing. 14. System for programming the purge of a poorly mixed NOx collector characterized by being substantially as described in this document, with reference to the attached drawing. 15. Vehicle with a poor combustion engine characterized by being substantially as described in this document with reference to the attached drawing. 1/3