FR2883922A1 - Vehicle`s internal combustion engine controlling method, involves emitting defect signal if conversion signal is less than threshold signal, where conversion signal is determined upstream and downstream of exhaust gas processing unit - Google Patents

Abstract

The method involves determining a conversion signal (etaIst) using a conversion determination unit (33) from exhaust gas components measured upstream and downstream of an exhaust gas processing device (15) placed in an exhaust gas zone (13). The conversion signal is compared with a threshold signal (etaS) using a comparator (43), and a defect signal (F1) is emitted if the conversion signal is less than the threshold signal. An independent claim is also included for a device for controlling an internal combustion engine.

Description

Field of the invention

  The invention relates to a method for managing an internal combustion engine with diagnosis of the exhaust gas zone of the internal combustion engine comprising at least one exhaust gas treatment device for converting at least one component. annoying exhaust fumes.

  The invention also relates to a device for implementing this method.

  State of the art DE 44 26 020 A1 discloses a method for monitoring the operability of a catalyst installed in the exhaust zone of an internal combustion engine. The monitoring is done by a temperature rise produced by the exothermic conversion of oxidizable components of the exhaust gas into the catalyst. Two temperature signals are determined; the first temperature signal corresponds to a measurement of the temperature downstream of the catalyst and the second temperature signal is calculated using a model.

  DE 103 58 195 A1 discloses a method of monitoring a component installed in the exhaust zone of an internal combustion engine; according to this method, the behavior of the low-pass filter defined by the heat capacity of the part is verified; this verification is done by using a measurement of a first exhaust gas temperature taken upstream of the monitored part and a second exhaust gas temperature taken by a temperature detector downstream of the monitored part. The described method makes it possible to monitor the part with regard to, for example, unauthorized manipulations. In the extreme case, the part to be monitored, for example a catalyst and / or a particulate filter, may have been completely removed. Monitoring is done either in the context of checks carried out to comply with the standards relating to gas emissions or during the normal operation of the internal combustion engine.

  Document DE 10 2004 031 624 A1, previously unpublished, discloses a method of managing a catalyst for cleaning the exhaust gases of an internal combustion engine and a device for carrying out process work; these must provide control or regulation of the level of reactive agent filling in the catalyst with respect to a predefined storage setpoint. The intentional predefinition of the storage con-sign value ensures, on the one hand, that for the non-stationary operating states of the internal combustion engine there is a sufficient quantity of reagent to eliminate as completely as possible at least one component hindering exhaust gas and that on the other hand avoids slippage of the reagent. This document describes a catalyst model which determines the level of reactive agent filling in the catalyst using the flow of reactant passing through the catalyst, where appropriate the mass flow rate of NOx oxides arriving in the catalyst, the where appropriate, the mass flow rate of NOx oxides leaving the catalyst and optionally a slip of the reactive agent is determined.

  OBJECT OF THE INVENTION The object of the present invention is to develop a method for managing an internal combustion engine with diagnostics in the zone of the exhaust gases in which an exhaust gas treatment device is provided for converting to minus an unwanted component of the exhaust gas; the invention also aims to develop a device for implementing this method.

  DESCRIPTION AND ADVANTAGES OF THE INVENTION For this purpose, the invention relates to a process of the type defined above, characterized in that a measurement of the conversion is determined from the exhaust gas components measured upstream of the device. exhaust gas treatment and downstream of the device and this measurement is compared to a predefined threshold value and if the threshold is exceeded downwards, a fault signal is emitted.

  The invention also relates to a device for the implementation of this method, this device being characterized by a control apparatus and an exhaust flap which applies the exhaust gas components to a detector to capture at least an unwanted component of the exhaust gas either upstream or downstream of the exhaust gas treatment device.

  The method according to the invention for managing an internal combustion engine provides a diagnosis of the exhaust gas zone equipped with an exhaust gas treatment device for converting at least one unwanted component of the exhaust gases. exhaust. From the exhaust gas components measured upstream, before the exhaust gas treatment device and downstream after this device, a measurement of the conversion is determined and compared with a predefined threshold. If we go below the threshold, we send a fault signal.

  The method according to the invention allows the diagnosis of the entire exhaust gas zone. For example, mechanical defects are recognized, for example, that the entire vein of the exhaust gases does not pass through the treatment device. Insofar as the exhaust gas treatment device comprises a catalyst, the information relating to the operability may relate to the coating of the catalyst. The method according to the invention makes it possible, in particular, to detect a manipulation made at the level of the exhaust gas zone such as, for example, the use of a dummy component in the exhaust gas treatment device or, for example, a coating. intentionally failed of a component installed in the exhaust gas treatment device. In addition, this makes it possible to detect the total absence of exhaust gas treatment device.

  In the simplest case, the threshold is predefined. The threshold can be set, for example, at a value of 50% of the predictable con-version measurement under the normal operating conditions of the exhaust gas treatment device. The threshold is preferably variable.

  A fault signal emitted when the threshold is exceeded downwards makes it possible, for example, to perform other diagnostics to de-limit the fault. In addition, the fault signal can be displayed to ask the driver of the vehicle to go to the garage.

  At least one component of the exhaust gas, determined upstream of the exhaust gas treatment device, for example at the inlet of the exhaust gas zone, can be calculated or measured.

  A development plans to determine as a measure of conversion, the performance of the exhaust gas treatment device. The efficiency results from the difference between the input and output exhaust gas components divided by the input exhaust components. The concentration of the exhaust gas components can be used. It is also possible to use the mass flow rate or the volume flow rate of these components. The efficiency of the exhaust gas treatment device is independent of the absolute values of the quantities used.

  Another development foresees as measure of the conversion, the reduction of the concentration or the mass flow / volume flow of the components of the exhaust gases.

  A development involves determining a measurement of the exhaust gas components upstream of the exhaust gas treatment device from at least one operating parameter of the internal combustion engine. This means saves a sensor or detector or a mechanical component of the exhaust gas to deflect the exhaust gas veins. As a parameter it is possible, for example, to use the rotational speed of the internal combustion engine and / or a fuel signal which corresponds to a torque and / or the temperature of the engine cooling water and / or the coefficient of recirculation of the gases. exhaust and / or other operating parameters.

  A corresponding development plans to compare the threshold with the conversion measurement, a threshold that sets operating conditions in the exhaust zone. For example, the temperature of the exhaust gas treatment device and / or the determination of a reactive agent in the exhaust gas zone and / or the mass flow rate of the exhaust gas can be taken into account.

  Insofar as the exhaust gas treatment device comprises at least one catalyst, the conversion of the undesirable components of the exhaust gas depends, for example, on the temperature of the catalytic surfaces. Since, for the conversion of the undesirable components of the exhaust gas, a reactive agent introduced into the exhaust gas zone is provided, from the determination of the reagent, the amount of reactive agent can be evaluated. stored in the catalyst and thus evaluate the yield. As a reactive agent there is for example ammonia or for example as the previous step, a urea-water solution. Ammonia is converted into the SCR catalyst (selective catalytic reduction SCR = SCR) NOx emissions nitrogen oxides of the internal combustion engine.

  Another development provides a delay for delaying the exhaust gas components measured downstream of the exhaust gas treatment unit to take into account the travel time of the exhaust gas components in the gas zone. exhaust before comparison with the components of the exhaust gas determined upstream of the exhaust gas treatment device.

  A development provides to provide the deficiency signal only if the threshold is exceeded down for at least a predetermined duration. This makes it possible to eliminate sporadic faults or resulting from fault signals.

  The device according to the invention for managing an internal combustion engine relates first of all to a control apparatus for implementing the method. The control apparatus preferably comprises at least one electrical memory in which the method is recorded in the form of a computer program.

  According to a development of the device according to the invention there is an exhaust gas shutter controlled by an electrical means receiving a sensor input of at least one unwanted component of the exhaust gas, but requested by the components of exhaust gas upstream or downstream of the exhaust gas treatment device.

  Drawings The present invention will be described hereinafter in more detail with the aid of embodiments shown schematically in the accompanying drawings in which: - Figure 1 shows the technical environment of the process of the invention, - Figure 2 shows a flowchart of a method according to the invention. DESCRIPTION OF EMBODIMENTS OF THE INVENTION FIG. 1 shows an internal combustion engine 10 whose intake zone 11 comprises an air gripping means 12 and whose exhaust gas zone 13 comprises a means for capturing air 12. reagent dosage 14 and an exhaust gas treatment device 15. The exhaust gas treatment device 15 is equipped with a temperature sensor 16. The exhaust gas zone 13 is further provided with an exhaust flap 17 for a first and a second exhaust gas supply 18, 19. The first exhaust gas supply 18 withdraws the exhaust gas upstream of the fuel treatment device. exhaust gas 15 and the second exhaust gas supply 19 withdraws the exhaust gas downstream of the exhaust gas treatment device 15 and supplies the exhaust gas to a detector 20. In the gas zone exhaust 13 we have a flow mas msabg exhaust gas.

  The air gripping means 12 provides an air signal msL to the control apparatus 30; the internal combustion engine 10 furnishes the rotational speed N, the temperature sensor 16 provides a temperature signal TKat and the detector 20 provides a NOx nitrogen oxide signal.

  The controller 30 supplies a fuel signal mK to the fuel metering device 31 on the internal combustion engine 10. A metering signal generator 32 provides a dosing signal to the reagent dosage means 14. of reagent msRea. Conversion determining means 33 provides an adjustment signal 34 to the exhaust flap 17.

  The air signal msL is provided by means of determining the conversion 33. The rotational speed signal or N-mode signal is supplied to a NOx nitrogen oxide determining means 35 which provides a raw emission signal. NOxvK nitrogen oxides both to the dosing signal generator 32 and to the conversion determining means 33. The NOx nitrogen oxides determination means 35 further receives a torque signal mi, a recirculation of the exhaust gas agr as well as the temperature of the cooling water TW.

  The msRea reagent assay signal is further provided to an integrator 40 which gives an amount of mRea reagent. The signal is also supplied to the dosing signal generator 32 and to a means setting a threshold 41.

  The temperature signal TKat supplied by the temperature sensor 16 is applied to both the dosing signal generator 32 and the threshold fixing means 41. The NOx nitrogen oxide signal supplied by the detector 20 is transmitted to the do-wise signal generator 32, by means of determination of the conversion 33 and at a means of determining a detection defect 42.

  The conversion determining means 33 provides an etalst conversion signal to a comparator 43 which further receives a threshold signal etaS provided by the threshold fixing means 41. The comparator 43 provides a switching signal 44 to a clock ( t) which transmits a first fault signal F 1. The detecting fault means 42 provides a second fault signal F2.

  Figure 2 shows the flow chart of the method of the invention. The process begins with a first functional block 50 in which the NOx nitrogen oxide signal is determined. In a functional block 51, the NOx nitrogen oxide determination means 35 determines the NOxvK crude nitrogen oxide emission signal. In the third functional block 52, the conversion determining means 33 determines the actual conversion etalst. In a fourth function block 53, the threshold setting means 41 sets the threshold value etaS.

  A first interrogation 54 which symbolizes the comparator 43 makes it possible to determine whether the actual conversion etalst is greater than or at least equal to the threshold value etaS. If this is the case, the first functional block 50 is returned. If this is not the case, the clock (t) is started in the fifth functional block 55.

  A first interrogation 56 checks whether the switching signal 44 still exists for the predetermined duration by the clock (t). If this is not the case, the first functional block 50 is returned. If this is the case, the first fault signal F1 is supplied in the sixth functional block 56. Then, in the seventh functional block 57, account is taken of the possible second fault signal F2.

  The method according to the invention proceeds as follows: The control device 30 determines the fuel signal or fuel metering signal mK supplied to the fuel metering device 31, for example as a function of the rotation speed N of the engine 10 as well as the position of the accelerator pedal of the vehicle, not shown, and where appropriate also as a function of the msL air signal supplied by the air gripping means 12. fuel mK corresponds to the mi torque that must provide the internal combustion engine 10 or that it already provides.

  The exhaust gases of the internal combustion engine contain at least one troublesome exhaust gas component that the exhaust gas treatment device 15 must reduce. In the following it is assumed for example that the annoying component of the exhaust gas is constituted by NOx emissions of NOx of the internal combustion engine 10.

  In order to reduce the NOx nitrogen oxide emissions by the internal combustion engine 10, a catalyst is provided, for example an NOx nitrogen oxide storage catalyst installed in the exhaust gas treatment device 15. In the exemplary embodiment, it is assumed that the catalyst associated with the exhaust gas treatment device 15 is an SCR catalyst (or alternatively called a RSC catalyst: catalyst providing selective catalytic reduction). This catalyst converts the NOx nitrogen oxides contained in the exhaust gas using a reactive agent. The reactive agent may be ammonia from, for example, the reagent dosage device 14 installed in the exhaust gas zone 13 and obtained from an aqueous solution of urea.

  The reagent flow rate is set by the reagent dosing signal msRea which is set by the dosing signal generator 32, for example as a function of the raw NOxvK nitrogen oxide emission signal transmitted by the reaction medium. NOx nitrogen oxides 35 are determined. The flow rate of the NOx nitrogen oxide reactive agent that the internal combustion engine 10 supplies to the exhaust gas zone 13 is thus adapted. In addition or alternatively, it is possible to use the NOx nitrogen oxides signal provided by the detector 20 as a function of NOx nitrogen oxides concentration downstream of the exhaust gas treatment device 15 for setting the msRea reagent dosing signal. In addition, the amount of reactive agent determined by the integrator 14 which provides, for example, a sliding integration of the msRea reagent dosing signal can be taken into account. In addition, it is also possible to take into account, in particular, the temperature of the catalyst SCR detected by the temperature sensor 16 supplying the temperature signal TKat.

  The temperature sensor 16 preferably detects the temperature of the exhaust gas directly upstream of the exhaust gas treatment device 15. Where appropriate, the temperature sensor 16 may be installed in the exhaust gas treatment device . 15

  The detector 20, which supplies the NOx nitrogen oxides signal, captures at least the concentration of NOx nitrogen oxides in the exhaust gas downstream of the exhaust treatment device 15. In the example embodiment shown, there is an exhaust flap 17 which sends on the detector 20 either the exhaust gas downstream of the exhaust gas treatment device 15 or the exhaust gas upstream of the The exhaust flap 17 is actuated according to the control signal 34 provided by the conversion determining means 33, and provides the connection between the exhaust gases. and the detector 20 either by the first exhaust gas supply 18 or by the second exhaust gas supply 19. This is why the detector 20 can detect, thanks to the exhaust gas flap 17, the concentration in nitrogen oxides NOx in the exhaust gases nt, either upstream or downstream of the exhaust gas treatment device 15.

  The emissions of nitrogen oxides NOx by the internal combustion engine 10 can be determined by means of a NOx nitrogen oxide determination means 35 from the operating parameters of the internal combustion engine 10 and be supplied as a NOxvK signal representing the raw NOx NOx emissions. Alternatively or additionally, it is possible to measure the concentration of NOx nitrogen oxides upstream of the exhaust gas treatment device 15. As already indicated, the use of the exhaust gas flap 17 makes it impossible to use another NOx nitrogen oxide sensor. By determining the emissions of NOx nitrogen oxides by the internal combustion engine 10 in different ways the plausibility of the values entered is checked.

  To apply the method according to the invention, it is intended to determine at least one component hindering exhaust gases upstream and downstream of the exhaust gas treatment device 15 according to the first two functional blocks 50, 51. , the conversion determining means 33 determines at least one measurement of the actual value of the conversion etalst of the exhaust gas component.

  The conversion determining means 33 preferably determines the efficiency of the conversion of the exhaust gas components. The efficiency is obtained from the difference of the exhaust gas components entering the exhaust gas treatment device 15 and leaving the exhaust gas treatment device 15 divided by the exhaust gas components. Incoming exhaust. The concentration of the exhaust gas components or the absolute values such as the mass flow rate or the volume flow rate of the exhaust gas components can be used for this purpose.

  Instead of determining the efficiency, the conversion determining means 33 may also use absolute quantities such as, for example, the difference in mass flow or volume flow to determine at least one measure of the conversion of the conversion. minus an annoying component of the exhaust gas.

  The conversion determining means 33 preferably provides a delay for delaying the exhaust gas component measured downstream of the exhaust gas treatment device 15 to account for the travel time of the exhaust gas components in the exhaust gas system. the exhaust gas zone 13 before comparing this value in the comparator 43 to the exhaust gas component obtained upstream of the exhaust gas treatment device 15.

  According to the fourth functional block 53, the threshold value etaS is fixed by the threshold fixing means 41. In a simple embodiment, the threshold value etaS is a fixed value corresponding for example to 50% of the minimum expected real conversion etalst. However, the threshold etaS is preferably set according to the operating conditions of the internal combustion engine 10 and in particular according to the operating conditions in the zone of the exhaust gases 13.

  The threshold or threshold value etaS may first depend on the temperature in the exhaust treatment device 15; this temperature can be evaluated or preferably measured at least approximately by the temperature sensor 16. In particular, if the exhaust gas treatment device 15 is equipped with an SCR catalyst, the threshold value etaS is preferably set. by the reactive agent of the SCR catalyst, preferably taking into account the temperature of the SCR catalyst; in fact, the accumulation capacity of an SCR catalyst for the reactive agent depends on the temperature. In particular, in addition or alternatively, the mass flow rate of the exhaust gas msabg, which is preferably calculated using the operating parameters of the internal combustion engine 10 such as, for example, the speed of rotation N and or the fuel metering signal mK and / or the air signal msL.

  The actual etalst conversion and the threshold value etaS are provided to the comparator 43. According to the first interrogation 54, the comparator 43 determines whether the measurement of the actual conversion is at least equal to the threshold value etaS. If this is the case, we return to the first functional block 50 because the diagnosis did not give a remarkable result. However, in this case, the comparator 43 supplies the switching signal 44 to the clock (t).

  According to the fifth function block 55, the switching signal 44 starts the clock (t). The second interrogation 56 checks in the clock (t) whether the switching signal 44 still exists for the duration predefined by the clock (t). If this is not the case, we return to the first functional block 50 because the diagnosis gave only a defect appearing sporadically or caused by random para-site signals. If after the time defined by the clock (t) the switching signal 44 is still present, the sixth function block 56 provides the first fault signal F 1.

  The first fault signal F 1 may for example be displayed to signal the driver of the vehicle that he must go to a garage. The first fault signal F1 is preferably stored in a default memory not shown and / or preferably used to initiate other diagnostics.

  The first fault signal F 1 indicates that there is a fault in the zone of the exhaust gas 13. The fault can for example correspond to an at least partial interruption of the passage of the exhaust gas stream of the zone exhaust gases 13 through the exhaust gas treatment device 15. This may result, for example, from a failure of the exhaust between the internal combustion engine 10 and the exhaust gas treatment device 15 Another possibility of defect can be found in the exhaust gas treatment device 15. For example, the cleaning effect of the exhaust gas treatment device with respect to the troublesome components of the exhaust gas treatment devices 15. exhaust may have deteriorated over time. Another possibility that the method of the invention detects with great reliability is that of unauthorized manipulation in the exhaust gas zone 13; it may for example be the installation of a dummy device instead of a usual exhaust gas treatment device, or an intentionally reduced implementation of the catalyst coating in the treatment device. exhaust gases 15.

  Another possible fault is that of the faulty NOx signal supplied by the detector 20. In the embodiment shown, the means for determining a detection defect 42 can look for a fault originating in the detector 20.

  Due to the possibility of several causes of defect, according to an advantageous development of the method of the invention, after the transmission of the first fault signal F1, first of all other measures are taken to delimit the defect.

Claims (12)

  1) A method of managing an internal combustion engine (10) with diagnosis of the exhaust gas zone (13) of the internal combustion engine (10) comprising at least one exhaust gas treatment device (15). ) for converting at least one disturbing component of the exhaust gas (NOx), characterized in that a measurement of the conversion (etalst) is determined from the exhaust gas components (NOx) measured upstream of the exhaust gas device. treatment of the exhaust gases (15) and downstream of the device (15) and this measurement is compared with a predefined threshold value (etaS) and if the threshold is exceeded downwards, a fault signal is emitted (F1) .   2) Method according to claim 1, characterized in that the measurement of the conversion (etalst) is the efficiency of the exhaust gas treatment device (15).   3) Process according to claim 1, characterized in that the measurement of the conversion (etalst) is the reduction of the concentration of the components of the exhaust gas (NOx).   4) Process according to claim 1, characterized in that a measurement of the exhaust gas components (NOx) upstream of the exhaust gas treatment device (15) is calculated from operating parameters (mi, N, agr, TW) of the internal combustion engine (10).   5) Method according to claim 1, characterized in that the threshold value (etaS) is set using operating conditions (mRea, TKat, msabg) in the exhaust gas zone (13). and / or operating conditions of the internal combustion engine (10).   6) Process according to claim 5, characterized in that the temperature (TKat) of the exhaust gas treatment device (15) and / or the dosage of a reactive agent introduced into the gas zone are taken into account. exhaust.   Method according to claim 1, characterized by a delay for the measured exhaust gas components (NOx) for delaying these components measured downstream of the exhaust gas treatment device (15) and taking into account the time of the - the course of the exhaust gas components (NOx) in the exhaust zone (13).   8) A method according to claim 1, characterized in that one emits the fault signal (F1) if the going beyond the threshold continues for at least a predefined duration.   9) Process according to claim 1, characterized in that the exhaust gas components are the emissions of nitrogen oxides (NOx) by the internal combustion engine (10).   10) Method according to claim 1, characterized in that one carries out other diagnoses after the emission of the fault signal (F1).   11) A device for managing an internal combustion engine (10), characterized by a control apparatus (30) for carrying out the method according to one of claims 1 to 10.   Device according to claim 11, characterized by an exhaust flap (17) which applies the exhaust gas components (NOx) to a detector (20) for capturing at least one unwanted component of the exhaust gases. exhaust (NOx) either upstream or downstream of the exhaust gas treatment device (15).