Emission control system for a diesel engine of a motor vehicle and associated method for detecting a malfunction of said system

Abstract

This method for detecting a malfunction of a control system (11) of pollutant emissions of an engine (1) equipped with a particulate filter (DPF) comprises the steps of: - determining a first maximum temperature at the filter inlet as a function of an instantaneous operating point of the engine; - determining a second maximum temperature at the filter inlet from the first maximum temperature, as a function of a measurement of the exhaust flow rate of the engine; - determining a third maximum temperature at the filter inlet corresponding to the minimum value between the second maximum temperature and the value of a temperature setpoint from control means (14) of the system (11), - calculating a difference between the third maximum temperature and a measurement of the temperature at the filter inlet; and - detecting a malfunction of the control system when the calculated difference exceeds a predetermined threshold difference.Figure for the abbreviation: [Fig 1].

Description

Title of the invention: System for controlling pollutant emissions from a diesel engine of a motor vehicle and associated method for detecting a malfunction of said system Technical field

[0001] The invention relates to a method for monitoring a pollutant emissions control system of a compression-ignition engine of a motor vehicle, in particular based on the detection of a malfunction of the system. It also relates to a system implementing this method as well as a motor vehicle equipped with such a system or implementing such a method. Previous techniques

[0002] Despite constant progress in the operation of internal combustion engines in motor vehicles, and more particularly diesel engines, the engines emit polluting particles which consist of soot produced during imperfect combustion in the engine.

[0003] According to the state of the art, it is known to trap these particles present in the exhaust gases by means of a particle filter installed in the exhaust line downstream of the combustion chambers of the engine. Such a filter is designed so as to be able to retain the particles present in the exhaust gases which pass through the filter. As the engine is used, the particles accumulate in the filter and lead to a progressive increase in exhaust back pressure which is detrimental to the proper functioning of the engine as well as to fuel consumption.

[0004] In order to restore optimal operation of the engine, it is necessary to regularly regenerate the particulate filter by burning the particles that have accumulated there. This combustion operation is made possible by an increase in the internal temperature of the particulate filter by increasing the temperature of the exhaust gases. To do this, a delayed injection of fuel is generally carried out into the combustion chambers of the engine. In particular, fuel can be injected just after top dead center during the expansion phase, which has the effect of increasing the temperature of the exhaust gases.

[0005] Thus, conventionally, particle filters operate periodically, in two phases. During a first phase, the filter stores particles emitted by the engine, and during a second phase, the particles stored in the filter are burned in order to regenerate the filter.

[0006] Generally, the regeneration of the particle filter is carried out periodically as soon as the particle mass in the filter becomes too high. This regeneration is triggered automatically when the engine is running. This management of particle filters is based on systems for estimating the mass quantity of particles present in the particle filter from the pressure difference, also called differential pressure, across the filter, from the volume flow rate passing through the filter and from filter operating models.

[0007] However, the mass of particles in the filter can only be identified by means of the differential pressure and the volume flow rate during the first phase of particle storage. Indeed, from the beginning of the second phase, the combustion of soot causes a rapid drop in the differential pressure, although the particle filter still contains a significant mass of soot. It is therefore impossible to estimate the mass of soot during the second phase from the differential pressure.

[0008] Therefore, a soot combustion model is generally used, for example initialized at the start of the second phase with a soot mass value estimated from the differential pressure measured at the end of the first phase, then progressively decremented as a function of the current conditions of temperature, exhaust gas flow rate and oxygen concentration.

[0009] Apart from the trivial case of stopping the engine by the driver, the second phase is generally stopped in the event of sufficient regeneration, i.e. when the soot combustion model indicates that the regeneration has succeeded in reducing the soot mass of the filter below a predefined minimum mass threshold.

[0010] In the event of insufficient regeneration, the second phase is still stopped when a predefined maximum regeneration time is reached. Such insufficient regeneration is generally the consequence of temperatures that are too low at the filter inlet, which do not allow the desired combustion of soot. Such temperatures can result either from a malfunction of the filter regeneration system, which is important to identify and correct, or simply from the vehicle's driving profile, for example in the event of a long idle phase or driving at very low speed. Such a vehicle driving profile leads to a thermal condition at the filter inlet that does not allow sufficient regeneration to be achieved, although the system is operating normally.

[0011] Several solutions for identifying a malfunction of the particle filter regeneration system can be considered. However, these solutions are not satisfactory.

[0012] For example, it is not enough to count the frequency of regenerations of the particle filter or the percentage of time spent on average in the regeneration phase. Indeed, such criteria can be linked to a loading speed of the filter anor significantly high, therefore depending on an increase in the speed of particle emission by the engine and not on a malfunction of the regeneration system.

[0013] Comparing the soot mass value from a soot combustion model at the end of a regeneration phase with the soot mass value obtained through differential pressure is also not satisfactory because by doing so, only a difference between two models is detected without definitely identifying a malfunction of the particle filter regeneration system.

[0014] Using closed-loop regulation of the temperature at the inlet of the particle filter, by monitoring the loop deviation, i.e. the difference between the temperature setpoint and the measured temperature, is still not satisfactory for detecting a malfunction, because this mainly leads to highlighting phases where the required power of the engine is insufficient to reach the temperature necessary for the combustion of soot. Statement of the invention

[0015] The aim of the invention is to enable the reliable detection of a malfunction of a particle filter regeneration system by excluding cases where the lack of efficiency of the regeneration would be linked to the driving profile of the vehicle.

[0016] The subject of the invention is a method for detecting a malfunction of a pollutant emissions control system of a diesel engine of a motor vehicle equipped with a particulate filter.

[0017] The method comprises steps of: - determination of a first maximum temperature at the filter inlet as a function of an instantaneous operating point of the engine; - determination of a second maximum temperature at the filter inlet from the first maximum temperature, based on a measurement of the engine exhaust flow; - determination of a third maximum temperature at the filter inlet corresponding to the minimum value between the second maximum temperature and the value of a temperature setpoint from the system control means, - calculation of a difference between the third maximum temperature and a measurement of the temperature at the filter inlet; and - detection of a malfunction of the control system when the calculated deviation exceeds a predetermined threshold deviation.

[0018] Such a method makes it possible to make the detection of malfunctions in the control system more reliable by excluding cases where insufficient regeneration is attributable to the profile of rolling.

[0019] According to one characteristic, the method further comprises a time calculation step in which a total malfunction time is calculated representing the sum of each period of time elapsed between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

[0020] For example, the method further comprises a step of transmitting an alert message or signal carried out when the total malfunction time exceeds a predetermined threshold duration.

[0021] According to another characteristic, the method further comprises a step of calculating a total enthalpy deficit received by the filter in which the sum of each integral with respect to the time of the product between an exhaust flow rate and a difference between the calculated deviation and the predetermined threshold deviation is calculated, for each period of time elapsed between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

[0022] For example, the method further comprises a step of transmitting an alert message or signal carried out when the total enthalpy deficit received by the filter exceeds a predetermined threshold enthalpy deficit.

[0023] According to another aspect, the invention relates to a system for controlling the polluting emissions of a diesel engine of a motor vehicle equipped with a particulate filter comprising:

[0024] - means for measuring an engine exhaust flow rate, a volume flow rate passing through the filter, a pressure difference between the inlet and outlet terminals of the filter, and a temperature at the inlet of the filter,

[0025] - calculation means capable of estimating a mass of soot in the filter from the in training from measurement methods,

[0026] - control means configured to control a regeneration of the filter at particles when the estimated soot mass of the filter exceeds a predetermined threshold mass.

[0027] According to one characteristic, the control system comprises means for determining a first maximum temperature at the inlet of the filter as a function of the instantaneous operating point of the engine; means for determining a second maximum temperature at the inlet of the filter from the first maximum temperature, as a function of a measurement of the exhaust flow rate of the engine; and means for determining a third maximum temperature at the inlet of the filter corresponding to the minimum value between the second maximum temperature and the value of a temperature setpoint required by the control means to regenerate the filter.

[0028] Advantageously, the calculation means are configured to calculate a difference between the third maximum temperature and a measurement of the filter inlet temperature, and configured to detect a malfunction of the control system when the calculated deviation exceeds a predetermined threshold deviation.

[0029] For example, the calculation means are configured to calculate a total malfunction time representing the sum of each period of time elapsed between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

[0030] For example, the calculation means are configured to calculate a total enthalpy deficit received by the filter representing the sum of each integral with respect to the time of the product between an exhaust flow rate and a difference between the calculated temperature difference and a predetermined threshold difference, for each period of time elapsed between the detection of a malfunction and the moment when the calculated difference becomes lower than or equal to the predetermined threshold difference.

[0031] Preferably, the control system comprises means for transmitting a message or an alert signal.

[0032] According to another aspect, the invention relates to a motor vehicle equipped with a diesel-type internal combustion engine implementing a method or equipped with a system for controlling pollutant emissions as described above. Brief description of the drawings

[0033] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0034] [Fig-1] shows an example of application of the invention;

[0035] [Fig.2] illustrates the evolution over time of several temperatures at the inlet of a particle filter according to the invention;

[0036] [Fig.3] illustrates a calculation of a total malfunction time according to an embodiment of the invention;

[0037] [Fig.4] illustrates a calculation of a total enthalpy deficit received by a particle filter;

[0038] [Fig.5] illustrates a flowchart of a malfunction detection method of a pollutant emission control system according to the invention;

[0039] [Fig.6] illustrates a flowchart of a method for detecting a malfunction according to an embodiment of the invention; and

[0040] [Fig.7] illustrates a flowchart of a method for detecting a malfunction according to one embodiment of the invention. Detailed description of at least one embodiment

[0041] [Fig.l] illustrates in a non-limiting manner the application of the invention to an internal combustion engine of a vehicle, which is here a diesel engine.

[0042] The engine 1 is conventionally equipped with a fresh air intake line comprising an intake manifold 2 connected on the one hand to the cylinders (three in number in the illustrated example) and on the other hand to a throttle body 3 making it possible to adjust the quantity of fresh air admitted. The throttle body 3 is connected to the fresh air intake via at least one pipe 4.

[0043] The engine 1 is provided with an exhaust line comprising an exhaust manifold 5 connected on the one hand to the cylinders and on the other hand to an air vent. The exhaust line comprises a particulate filter referenced FAP. The particulate filter FAP is associated with a differential pressure sensor (not shown) which is capable of measuring the pressure difference AP between the inlet and outlet terminals of the filter.

[0044] The engine 1 also comprises a system for partial recirculation of the exhaust gases at the engine intake, called the EGR circuit (from the English acronym for: “Exhaust Gas Recycling”), making it possible to take a portion of the exhaust gases from the exhaust line downstream of the FAP particle filter and to recycle it in the intake line after having reduced the temperature by means of a heat exchanger 6. The EGR circuit is provided with an EGR valve 7 making it possible to control the flow rate of recirculated gases.

[0045] In the embodiment illustrated by [Fig.l], the engine 1 is provided with a turbocharger 8 whose compressor part 8a is arranged in the fresh air intake line upstream of the throttle body 3 so as to increase the supply pressure of the engine 1 with fresh air. The turbine part 8b is arranged in the exhaust line so as to be driven by the exhaust gases. The EGR circuit can then be at low pressure as illustrated in [Fig.l] if the EGR circuit is arranged upstream of the compressor 8a and downstream of the turbine 8b. It can be at high pressure if the EGR circuit is arranged downstream of the compressor 8a and upstream of the turbine 8b.

[0046] Given the presence of such an EGR circuit, the throttle body 3 of the engine serves to regulate the total flow rate of the engine intake gases, comprising a flow rate of fresh air and a flow rate of recycled gases.

[0047] The flow rate of the recycled gases can be adjusted using the EGR valve 7, the flow rate of air admitted into the engine then being obtained indirectly, by difference. In a variant, it is also possible to adjust the air flow rate alone directly by adjusting the air intake valve 9 of the intake circuit, so as to obtain a desired flow rate setpoint. The flow rate of the recycled gases is then obtained indirectly by difference between the total flow rate and the flow rate of fresh air.

[0048] The total flow rate of gases admitted into the engine is obtained by adjusting the value of the pressure prevailing in the intake manifold 2 of the engine 1, taking into account the temperature and a filling model.

[0049] To achieve this, a pressure sensor 2a and a temperature sensor 2b are provided in the intake manifold 2. The pressure is adjusted by adjusting the position of the throttle body 3.

[0050] In the case not shown where the engine does not have an EGR circuit, there is generally only one throttle body 3 to regulate the only flow of gas admitted into the engine which is the flow of fresh air. There is no air intake valve 9.

[0051] The engine 1 is equipped with a system 11 for controlling pollutant emissions from the engine. The control system 11 comprises measuring means 12, calculating means 13 and control means 14.

[0052] The measuring means 12 are configured to measure operating parameters of the engine, in particular relating to the flow rates, temperatures and pressures in the intake and exhaust circuits of the engine.

[0053] The calculation means 13 are configured to estimate the mass of soot in the FAP filter from the information from the measurement means 12.

[0054] The control means 14 are configured to control the regeneration of the FAP filter when the estimated soot mass of the filter exceeds a predetermined threshold mass. The control means 14 typically comprise a regulator of the temperature at the inlet of the FAP filter configured to control the engine settings as a function of a temperature setpoint Tes required to regenerate the filter, depending for example on the mass contained in said filter.

[0055] The control system 11 further comprises a memory module (not shown).

[0056] The control system 11 comprises means for determining a first T1, a second T2 and a third T3 maximum temperature.

[0057] The determination of a first maximum temperature Tl at the inlet of the FAP filter is carried out from a predetermined map available in the memory module of the system, as a function of the instantaneous operating point of the engine.

[0058] For example, the mapping links each operating point of an engine 1 to a maximum temperature at the inlet of the FAP filter, taking into account the values ​​of engine adjustment parameters such as, for example, the injection phasing and the close or late injection flow rates. Such a mapping can be obtained by an identification procedure carried out in particular on an engine test bench after a prior stabilization phase.

[0059] The first maximum temperature T1 represents an estimate of the maximum temperature achievable at the inlet of the FAP filter for any non-failing engine, including dispersed, i.e. comprising components at the limit of their production tolerances.

[0060] However, the first maximum temperature T1 can only be reached after a sufficiently long time taking into account the dynamics of the temperature regulator and the thermal inertia of the exhaust circuit linked to its mass.

[0061] It is therefore useful to filter the first maximum temperature T1, for example, as a function of a measurement of the engine exhaust flow rate, in order to determine a second maximum temperature T2 representative of a maximum filtered temperature achievable at the inlet of the FAP filter for any non-failing engine, at the current operating point of the engine, at each instant of the regeneration of the particle filter.

[0062] The second maximum temperature T2 is likely to exceed the temperature setpoint Tes required at the inlet of the FAP filter for filter regeneration.

[0063] It is therefore useful to determine a third maximum temperature T3 at the inlet of the FAP filter corresponding to the minimum value between the second maximum temperature T2 and the value of the temperature setpoint Tes required by the control means 14 for the regeneration of the filter.

[0064] The third maximum temperature T3 represents an estimate of the temperature at the inlet of the FAP filter that is realistic and achievable for a non-failing engine.

[0065] In other words, the third maximum temperature T3 is an estimate of the temperature at the inlet of the FAP filter that can be reached with an engine that does not have any faults, regardless of the operating point of the engine or the driving profile of the vehicle.

[0066] [Fig. 2] illustrates the evolution over time of the first T1, second T2 and third T3 maximum temperatures according to a driving profile following a speed of the vehicle 15 represented in parallel. In this figure, the curves 16 and 17 respectively represent the temperature measured at the inlet of the FAP filter and the temperature setpoint Tes required by the control means 14.

[0067] The calculation means 13 are configured to calculate a difference between the third maximum temperature T3 and a measurement of the temperature 16 at the input of the FAP filter.

[0068] The calculation means 13 are configured to detect a malfunction of the control system when the calculated deviation exceeds a predetermined threshold deviation, in particular for a predetermined abnormally high duration.

[0069] It thus becomes possible to detect a malfunction of the engine's pollutant emissions control system by excluding cases where the lack of regeneration efficiency would be linked to the vehicle's driving profile, and therefore to engine operating points for which the required temperature at the inlet of the particulate filter Tes is simply not achievable.

[0070] In one embodiment, the calculation means 13 are configured to calculate a total malfunction time representing the sum of each time period elapsed time between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

[0071] [Fig.3] illustrates the calculation of a total malfunction time.

[0072] In the figures, the same references are used to designate the same elements.

[0073] In the example illustrated in [Fig. 3], curve 19 is offset relative to curve T3 by a temperature value, or safety margin 18, representative of the measurement and modeling errors and which is equal to the predetermined threshold deviation. Curve 20 illustrates the variation in the total malfunction time. It should be noted that the total malfunction time increases when the temperature measured at the inlet of the FAP filter, represented by curve 16, is lower than the corresponding value of curve 19. In other words, the total malfunction time at a given instant represents the total of all the durations during which the difference between the temperature measured at the inlet of the FAP filter and the third maximum temperature T3 was greater than the safety margin 18.

[0074] In another embodiment, the calculation means 13 are configured to calculate a total enthalpy deficit received by the FAP filter representing the sum of each integral with respect to the time of the product between an instantaneous exhaust flow rate and a difference between the calculated deviation and the predetermined threshold deviation, for each period of time elapsed between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

[0075] [Fig.4] illustrates the calculation of a total enthalpy deficit received by the FAP filter. Curve 21 represents the variation of the total enthalpy deficit received by the FAP filter. The total deficit corresponds to the sum of each integral with respect to time of the product between an instantaneous exhaust flow rate and the difference between curves 19 and 16, for each period of time elapsed between the detection of a malfunction and the moment when the calculated difference becomes less than or equal to the predetermined threshold difference. To facilitate the calculation, each area 22 can be discretized into time intervals sufficiently small so that the exhaust flow rate can be considered constant over each interval.

[0076] Alternatively, it remains possible for the calculation means 13 to be configured to calculate both the total enthalpy deficit received by the filter and the total malfunction time.

[0077] The control system 11 comprises means for transmitting a message or an alert signal when the total malfunction time exceeds a predetermined threshold duration and / or when the total enthalpy deficit received by the filter exceeds a predetermined threshold enthalpy deficit.

[0078] The method for detecting a malfunction of the control system of the polluting emissions according to the invention is represented by the flowchart illustrated in [Fig.5].

[0079] During a first step 23, a first maximum temperature T1 is determined at the inlet of the FAP filter from a predetermined map available in a memory module of the control system, as a function of an instantaneous operating point of the engine. The operating point generally corresponds to parameters representative of the operation of the engine such as the speed and the load. The determination of the operating point is generally available from a high-level control unit (not referenced).

[0080] During a second step 24, a second maximum temperature T2 is determined at the inlet of the filter from the first maximum temperature T1, as a function of a measurement of the exhaust flow rate of the engine, taking into account the thermal inertia of the exhaust circuit.

[0081] During a third step 25, a third maximum temperature T3 is determined at the input of the filter corresponding to the minimum value between the second maximum temperature T2 and the value of a temperature setpoint Tes from control means 14 of the system 11.

[0082] The method continues with a step 26 of calculating a difference between the third maximum temperature T3 and the measurement of the temperature at the filter inlet.

[0083] During the following step 27, it is determined whether the calculated deviation exceeds a predetermined threshold deviation.

[0084] If this is the case, a malfunction of the control system is detected (step 28). The method then returns to the first step 23.

[0085] If this is not the case, the method returns to the first step 23.

[0086] The succession of steps 23 to 28, referenced 29, makes it possible to monitor the normal operation of the control system.

[0087] As illustrated in [Fig.6], the method may comprise a time calculation step 30 in which a total malfunction time is calculated representing the sum of each time lapse between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

[0088] In the following step 31, it is determined whether the total malfunction time exceeds a predetermined threshold duration. It should be noted that if the regeneration of the particle filter is interrupted (for example by an engine shutdown), the duration threshold can be adjusted, with a temperature difference, to the time actually spent in regeneration.

[0089] If this is the case, the method continues with a step 32 of transmitting a message or alert signal intended to warn the driver of the malfunction of the system.

[0090] If this is not the case, the method returns to step 23.

[0091] As illustrated in [Fig.7], the method may comprise a step 33 of calculating a total enthalpy deficit received by the filter in which the sum of each integral with respect to the time of the product between an exhaust flow rate and a difference between the calculated deviation and the predetermined threshold deviation is calculated, for each period of time elapsed between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

[0092] In the following step 34, it is determined whether the total enthalpy deficit received by the filter exceeds a predetermined threshold enthalpy deficit. It should be noted that if the regeneration of the particle filter is interrupted (for example by a shutdown of the engine), the enthalpy deficit threshold can be adjusted to the time actually spent in regeneration.

[0093] If this is the case, the method continues with a step 32 of transmitting a message or alert signal intended to warn the driver of the malfunction of the system.

[0094] If this is not the case, the method returns to step 23.

[0095] Alternatively, it remains possible for the method to carry out steps 30 of in parallel calculation of time and 33 of calculation of the total enthalpy deficit received and that steps 31 and 34 are merged.

[0096] Alternatively, it remains possible to carry out step 32 of transmitting an alert message or signal immediately after step 28 of detecting a malfunction.

Claims

Claims

1. Method for detecting a malfunction of a control system (11) for the pollutant emissions of a diesel engine (1) of a motor vehicle equipped with a particulate filter (FAP) characterized in that it comprises steps of: - determining a first maximum temperature (Tl) at the inlet of the filter (FAP) as a function of an instantaneous operating point of the engine (1); - determining a second maximum temperature (T2) at the inlet of the filter (FAP) from the first maximum temperature (Tl), as a function of a measurement of the exhaust flow rate of the engine (1);- determination of a third maximum temperature (T3) at the inlet of the filter (FAP) corresponding to the minimum value between the second maximum temperature (T2) and the value of a temperature setpoint (Tes) from control means (14) of the system (11), - calculation of a difference between the third maximum temperature (T3) and a measurement of the temperature at the inlet of the filter (FAP); and - detection of a malfunction of the control system (11) when the calculated difference exceeds a predetermined threshold difference.;

2. The method of claim 1, further comprising a time calculation step in which a total malfunction time is calculated representing the sum of each time period elapsed between the detection of a malfunction and the time when the calculated deviation becomes less than or equal to the predetermined threshold deviation.

3. Method according to claim 2, further comprising a step of transmitting an alert message or signal carried out when the total malfunction time exceeds a predetermined threshold duration.

4. The method of claim 1, further comprising a step of calculating a total enthalpy deficit received by the filter (FAP) in which the sum of each integral with respect to the time of the product between an exhaust flow rate and a difference between the calculated deviation and the predetermined threshold deviation is calculated, for each period of time elapsed between the detection of a malfunction and the moment when the deviation calculated becomes lower than or equal to the predetermined threshold deviation.

5. Method according to claim 4, further comprising a step of transmitting an alert message or signal carried out when the total enthalpy deficit received by the filter exceeds a predetermined threshold enthalpy deficit.

6. Control system (11) for pollutant emissions from a diesel engine (1) of a motor vehicle equipped with a particulate filter (FAP) comprising: - means (12) for measuring an engine exhaust flow rate, a volume flow rate passing through the filter, a pressure difference between inlet and outlet terminals of the filter, and a temperature at the inlet of the filter, - calculation means (13) capable of estimating a mass of soot in the filter from information from the measuring means, - control means (14) configured to control a regeneration of the particulate filter when the estimated soot mass of the filter exceeds a predetermined threshold mass, characterized in that it comprises: - means for determining a first maximum temperature (Tl) at the inlet of the filter (FAP) as a function of the instantaneous operating point of the engine (1); - means for determining a second maximum temperature (T2) at the inlet of the filter (FAP) from the first maximum temperature (Tl), as a function of the measurement of the exhaust flow rate of the engine (1); - means for determining a third maximum temperature (T3) at the inlet of the filter (FAP) corresponding to the minimum value between the second maximum temperature (T2) and the value of a temperature setpoint required by the control means (14) to regenerate the filter, the calculation means (13) being configured to calculate a difference between the third maximum temperature (T3) and a measurement of the temperature at the inlet of the filter, and configured to detect a malfunction of the control system (11) when the calculated deviation exceeds a predetermined threshold deviation.

7. System according to claim 6 wherein the calculation means (13) are configured to calculate a total malfunction time representing the sum of each period of time elapsed between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

8. System according to claim 6 in which the calculation means (13) are configured to calculate a total enthalpy deficit received by the filter (FAP) representing the sum of each integral with respect to the time of the product between an exhaust flow rate and a difference between the calculated deviation and the predetermined threshold deviation, for each period of time elapsed between the detection of a malfunction and the moment when the calculated deviation becomes lower than or equal to the predetermined threshold deviation.

9. System according to any one of claims 6 to 8 comprising means for transmitting a message or an alert signal.

10. Motor vehicle equipped with a diesel-type internal combustion engine (1) implementing a method according to any one of claims 1 to 5 or equipped with a pollutant emissions control system (11) according to any one of claims 6 to 9.

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