FR3065987A1 - METHOD FOR ASSISTING THE DIAGNOSIS OF FUNCTIONAL ELEMENTS OF AN EXHAUST GAS DELEGATION SYSTEM OF A HEAT ENGINE - Google Patents

Abstract

The invention relates mainly to a method of assisting in the diagnosis of functional elements (4, 6, 7, 8) of a system for the pollution control (3) of the exhaust gas, characterized in that it comprises the following steps a step of reading a value of a diagnostic parameter of the functional elements (4, 6, 7, 8) of the pollution control system (3), a step of comparing the value of the diagnostic parameter with respect to at a limit threshold, and - in the case where the value of the diagnostic parameter is close to the limit threshold, said method comprises: - a step of calculating an alternative course of the motor vehicle with respect to a usual course, the alternative course gathering driving conditions necessary for the diagnosis of the functional elements (4, 6, 7, 8) of the pollution control system (3), and - a step of displaying the previously calculated alternative path on a screen of a geolocation system ( 12).

Description

METHOD FOR ASSISTING THE DIAGNOSIS OF FUNCTIONAL ELEMENTS OF AN EXHAUST EMISSION CONTROL SYSTEM FOR A THERMAL ENGINE

The present invention relates to a method of assisting in the diagnosis of functional elements of an exhaust gas pollution control system of a heat engine.

In a manner known per se, the heat engines are cleaned using several functional pollution control elements. Thus, for a diesel type engine for example, it will be possible to install on the exhaust line an oxidation catalyst (or "DOC" for "Diesel Oxidation Catalyst") allowing the oxidation of hydrocarbons (HC) and carbon monoxide (CO) into carbon dioxide and water, or a passive nitrogen oxide adsorber (or "PNA" for "Passive NOx Adsorber" in English) which allows the same reactions to be carried out as oxidation catalyst and also has the ability to store nitrogen oxides at low temperature (when the SCR catalyst is not active) and to destock them at higher temperature (when the SCR catalyst is active). This selective catalytic reduction system catalyst (or "SCR" for "Selective Catalytic Reduction" in English) makes it possible to reduce the nitrogen oxides (NOx) contained in the exhaust gases, while a particle filter makes it possible to trap particles contained in exhaust gases, in particular in the form of soot. If necessary, it is possible to use a reduction catalyst (or "ASC" for "Ammonia Slip Catalyst" in English) to remove the ammonia (NH3) in excess in the exhaust gases.

These depollution functional elements must be diagnosed regularly by the vehicle to verify their proper functioning. Thus, the on-board diagnostic standard (or "OBD" for "On Board Diagnostic" in English) imposes an efficiency report in service, or "IUPR" ratio for "In-Use Performance Ratio" in English which should not be exceeded so that the diagnostic of the functional elements of depollution is carried out on a regular basis.

However, the diagnosis requiring specific driving conditions to be carried out, it is possible that certain types of conductors, called "critical", have driving profiles not fulfilling these conditions often enough or long enough to satisfy this ratio . This is particularly the case when the driving conditions for a diagnosis are met (stabilized taxiing and sufficient exhaust gas temperature to activate the depollution functional elements) and that the diagnosis of the depollution functional elements has started, but the driver shuts down the engine before the diagnosis can be completed.

The invention aims to effectively remedy this drawback by proposing a method for assisting in the diagnosis of functional elements of an exhaust gas depollution system mounted on an exhaust line of a heat engine, in particular for a motor vehicle, characterized in that it comprises the following steps: - a step of reading a value of a parameter for diagnosing the functional elements of the depollution system, - a step of comparing the value of the parameter of diagnosis with respect to a limit threshold, and - in the case where the value of the diagnostic parameter is close to the limit threshold, the method comprises: - a step of calculating an alternative journey of the motor vehicle with respect to a usual journey allowing to go from a starting point to an ending point, the alternative route bringing together the driving conditions necessary for the diagnosis of the functional elements of the depolluti system on, and - a step of displaying the alternative route previously calculated on a screen of a geolocation system.

The invention thus makes it possible to obtain a driving aid making it possible to promote the diagnostics of the functional elements of depollution of the motor vehicle. In addition, the invention makes it possible to bring together all the driving conditions necessary for the diagnosis of the depollution functional elements so as not to exceed the limit threshold of the IUPR ratio.

According to one implementation, the value of the diagnostic parameter of the functional elements of the pollution control system corresponds to a ratio between a number of times a diagnosis has been carried out completely divided by a number of times the motor vehicle has encountered standard driving conditions to start a diagnosis.

According to one implementation, the value of the diagnostic parameter of the pollution control system is read from a memory of an engine computer of the motor vehicle.

According to one implementation, the alternative route includes stabilized taxiing phases long enough to allow the diagnosis of the functional elements of the pollution control system, as well as a temperature of the exhaust gases sufficient to ensure that the entire exhaust line, including sensors, is active.

According to one implementation, the alternative route may have a duration of at least ten seconds of stabilized driving, and be calculated to allow reaching an exhaust gas temperature above 200 ° C.

According to one implementation, the alternative route is offered transparently by default to a driver of the motor vehicle.

According to one implementation, the usual route and the alternative route, called self-maintenance route, are proposed for selection on the screen of the geolocation system.

According to one implementation, in the case where the motor vehicle stops before having completed the alternative route, a new alternative route making it possible to carry out the diagnostics of the functional elements of the depollution system is proposed when restarting the motor vehicle.

According to one implementation, the alternative route is calculated by a remote server taking into account data from the motor vehicle, in particular the value of the diagnostic parameter of the functional elements of the depollution system and the usual route calculated by the geolocation, to offer an adapted alternative route.

According to one implementation, the step of reading the value of the diagnostic parameter of the functional elements of the depollution system is carried out at the time of activation of the geolocation system.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given only by way of illustration but in no way limit the invention.

Figure 1 is a schematic representation of an exhaust line provided with an exhaust gas depollution system whose operation is supervised by a computer according to the present invention; Figure 2 is a diagram of the different stages of the method of assisting in the diagnosis of functional elements of the exhaust gas depollution system according to the present invention.

Figure 1 shows an exhaust line 1 of a heat engine 2, in particular of a motor vehicle, on which is mounted a pollution control system 3 of the exhaust gases. This depollution system 3 includes functional elements, such as a 4 Diesel oxidation catalyst (or "DOC" for "Diesel Oxidation Catalyst") allowing the oxidation of hydrocarbons (HC) and carbon monoxide (CO) carbon dioxide and water; as well as a pollution control unit 5 comprising a catalyst 6 of selective catalytic reduction system (or "SCR" for "Selective Catalytic Reduction" in English) and a particle filter 7. An injector 8 is positioned between the oxidation catalyst 4 Diesel (DOC) and the pollution control unit 5.

The SCR system is suitable for injecting a reducer into the exhaust line 1 in order to transform the nitrogen oxides (NOx) released by the engine 2 into nitrogen and water. This reducer is routed to the injector 8 via a pipe by means of a pump-gauge module (not shown) located for example at the level of the trunk of the vehicle.

A computer 10 (or ECU for "Engine Control Unit" in English) associated with a memory 11 provides in particular the control of the heat engine 2, as well as management of the various functional elements 4, 6, 7, 8.

The engine computer 10 is in communication with a geolocation system 12, for example by satellite (or "GPS" for "Global Positioning System" in English).

Described below, with reference to Figure 2, the different stages of the diagnostic assistance method of the functional elements 4, 6, 7, 8 of the exhaust gas depollution system 3 according to the present invention .

In a step 101, the engine computer 10 reads from memory 11 a value of a diagnostic parameter of the functional elements 4, 6, 7, 8 of the pollution control system 3. The reading step 101 can be carried out when activating the satellite geolocation system 12.

The diagnostic parameter is a ratio between a number of times a diagnosis has been carried out completely and could have detected a faulty part divided by a number of times the motor vehicle has encountered standard driving conditions enabling a start to be made. diagnostic. This ratio, called IUPR ratio for "In-Use Performance Ratio" in English, is calculated in real time by the engine computer 10. This ratio is less than 1 because the number of times the driving conditions are met to start a diagnosis is greater than the number of times the diagnosis has actually been carried out, insofar as the driver frequently stops his vehicle or returns to unfavorable driving conditions before the end of the diagnosis, which may take several seconds.

In a step 102, the value read of the IUPR ratio is compared with a limit threshold corresponding to a value imposed by a standard, in this case equal to 0.336. To comply with the standard, the IUPR ratio must be kept above this limit threshold.

In the case where the value of the IUPR ratio is close to the limit threshold, the geolocation system 12 calculates, in a step 103, an alternative route of the motor vehicle with respect to a usual route making it possible to go from one point from departure to an arrival point. By value "close to the limit threshold" means a value equal to plus minus 10% of this limit threshold value. This alternative route is displayed on a screen of the geolocation system 12 in a step 104.

The alternative route brings together the driving conditions necessary for the diagnosis of the functional elements 4, 6, 7, 8 of the pollution control system 3. Thus, the alternative route includes stabilized taxiing phases long enough to allow the diagnosis of functional elements 4, 6, 7, 8 of the pollution control system 3, and to reach an exhaust gas temperature sufficient to ensure that the entire exhaust line 1, including sensors, is active. For example, the alternative route could have a duration of at least ten seconds of stabilized driving, and be calculated to allow an exhaust gas temperature greater than 200 ° C to be reached.

Of course, the alternative route is calculated only when the usual route, which corresponds for example to the shortest or fastest route to go from the starting point to the finishing point, does not allow to have the conditions of taxiing necessary for the diagnosis of the functional elements 4, 6, 7, 8 of the pollution control system 3.

The alternative route is advantageously calculated by a remote server taking into account data from the motor vehicle, in particular the value of the IUPR ratio of the functional elements 4, 6, 7, 8 of the pollution control system 3 and the usual route calculated by the satellite geolocation system 12, to offer the suitable alternative route.

The alternative route can be offered transparently, by default, to the driver of the motor vehicle. In this case, the driver does not notice the modification of the usual route.

As a variant, the usual route and the alternative route, called self-maintenance route, may be offered to the driver who can select the route of his choice on the screen of the geolocation system 12.

In the event that the motor vehicle stops before having completed the alternative route which would have made it possible to correctly carry out the diagnosis of the functional elements 4, 6, 7, 8 of the pollution control system 3, a new alternative route is offered when the motor vehicle is restarted.

In addition, it is possible to verify that the IUPR ratio of the functional elements 4, 6, 7, 8 of the pollution control system 3 has changed during the alternative route, and to adapt the route of the vehicle if the diagnoses that the '' we wish to perform on certain phases of the route ultimately could not take place, for example in the case of a third party accident or unplanned traffic jams.

Claims (10)

1. Method for assisting in the diagnosis of functional elements (4, 6, 7, 8) of an exhaust gas depollution system (3) mounted on an exhaust line (1) of a heat engine (2), in particular for a motor vehicle, characterized in that it comprises the following steps: - a reading step (101) of a value of a diagnostic parameter of the functional elements (4, 6, 7, 8) of the depollution system (3), - a step of comparing (102) the value of the diagnostic parameter with respect to a limit threshold, and - in the case where the value of the diagnostic parameter is close to the limit threshold, said method includes: - a step of calculating (103) an alternative route of the motor vehicle with respect to a usual route making it possible to go from a starting point to an arrival point, the alternative route bringing together the necessary driving conditions to the diagnosis of the functional elements (4, 6, 7, 8) of the depollution system (3), and - a display step (104) of the alternative route previously calculated on a screen of a geolocation system (12). 2. Method according to claim 1, characterized in that the value of the diagnostic parameter of the functional elements (4, 6, 7, 8) of the pollution control system (3) corresponds to a ratio between a number of times that a diagnosis has carried out completely divided by the number of times the motor vehicle has encountered standard driving conditions enabling diagnosis to be started. 3. Method according to claim 1 or 2, characterized in that the value of the diagnostic parameter of the pollution control system (3) is read from a memory (11) of an engine computer (10) of the motor vehicle. 4. Method according to any one of claims 1 to 3, characterized in that the alternative route comprises stabilized taxiing phases long enough to allow the diagnosis of the functional elements (4, 6, 7, 8) of the system of depollution (3), as well as an exhaust gas temperature sufficient to ensure that the entire exhaust line (1), including sensors, is active. 5. Method according to claim 4, characterized in that the alternative route has a duration of at least ten seconds of stabilized driving, and is calculated to allow reaching an exhaust gas temperature above 200 ° C. 6. Method according to any one of claims 1 to 5, characterized in that the alternative route is proposed transparently by default to a driver of the motor vehicle. 7. Method according to any one of claims 1 to 5, characterized in that the usual route and the alternative route, called self-maintenance route, are proposed for selection on the screen of the geolocation system (12). 8. Method according to any one of claims 1 to 7, characterized in that, in the case where the motor vehicle stops before having completed the alternative route, a new alternative route making it possible to carry out the diagnostics of the functional elements (4, 6, 7, 8) of the pollution control system (3) is proposed when the motor vehicle is restarted. 9. Method according to any one of claims 1 to 8, characterized in that the alternative route is calculated by a remote server taking into account data from the motor vehicle, in particular the value of the diagnostic parameter of the functional elements (4, 6 , 7, 8) of the depollution system (3) and the usual route calculated by the geolocation system (12), to propose an adapted alternative route. 10. Method according to any one of claims 1 to 9, characterized in that the step of reading (101) the value of the diagnostic parameter of the functional elements (4, 6, 7, 8) of the depollution system ( 3) is performed at the time of activation of the geolocation system (12).