FR2929643A1 - Particle filter regenerating method for exhaust line of motor vehicle's diesel engine, involves stopping fuel injection when total quantity of heat energy provided by gas from starting of injection, is higher than determined energy quantity - Google Patents

Abstract

The method involves determining a parameter representing total quantity of heat energy that is provided by exhaust gas in an inlet of a particle filter (5), from starting of injection of vaporized fuel in an exhaust line (1) of a heat engine i.e. diesel engine, of a motor vehicle. The injection of the vaporized fuel is stopped when total quantity of heat energy that is provided by the exhaust gas in the inlet of the filter from the starting of the fuel injection, is higher than quantity of determined heat energy. An independent claim is also included for a device for regenerating a particle filter of an exhaust line of a motor vehicle, comprising a vaporized fuel injecting unit.

Description

The present invention relates generally to the exhaust lines of motor vehicles. More specifically, the invention relates, in a first aspect, to a method of regenerating a particulate filter of a motor vehicle exhaust line, the exhaust line comprising a catalytic purification member placed upstream of the filter The method is of the type comprising the steps of: starting an injection of a vaporized fuel into the exhaust line upstream of the catalytic purification member; stopping the injection of the fuel in vaporized form into the exhaust line when the regeneration of the particulate filter is completed. Such a method is known from WO 2007/079832, which describes that the fuel injection in vaporized form is carried out for a predetermined duration.

This predetermined duration does not take into account the evolution of the operation of the engine during the regeneration. In some cases, the particulate filter may not be fully regenerated at the end of the predetermined period of time. In this context, the invention aims to propose a regeneration process that is more efficient.

To this end, the invention relates to a regeneration process of the aforementioned type, characterized in that it comprises a step of determining a magnitude representative of the total amount of heat energy provided by the exhaust gas input of the particulate filter since the start of the fuel injection, the step of stopping the injection of the fuel in vaporized form being implemented when the total amount of heat energy supplied by the exhaust gas at the inlet of the particulate filter since the start of fuel injection is greater than a predetermined amount of heat energy. The method may also have one or more of the following characteristics, considered individually or in any technically possible combination: it comprises, after the injection start-up step, a periodic acquisition step of quantities representative of the flow rate of exhaust gas produced by the vehicle engine and the temperature of the exhaust gas between the catalytic purification unit and the particulate filter, the total amount of heat energy supplied by the exhaust gas at the inlet of the filter wherein the fuel injection rate is calculated as a function of the acquired exhaust gas flow rates produced by the vehicle engine and the exhaust gas temperature between the catalytic purification member and the fuel filter. particles; the fuel is injected at an average mass flow rate determined according to the load and / or the engine speed of the motor vehicle; the exhaust gases have variable temperatures downstream of the catalytic purification unit and downstream of the particulate filter, and in that said average mass flow rate is independent of the variations in the temperature of the exhaust gas downstream of the catalytic purification unit and downstream of the particulate filter; the method comprises, after the step of starting the injection, a step of periodically acquiring a quantity representative of the temperature of the exhaust gas leaving the engine of the vehicle, the injection at a determined average mass flow rate being interrupted if the acquired temperature is greater than a predetermined maximum temperature; the method comprises, before the step of starting the injection, a step of acquiring a magnitude representative of the temperature between the catalytic purification element and the particulate filter, the injection starting step fuel being implemented only if said acquired temperature is greater than a predetermined ignition temperature; the method comprises a step of performing post-injections of fuel in the combustion chambers of the engine under conditions such that the fuel injected during the post-injections at least partially burns and increases the temperature of the exhaust gas, said a step of performing post-injections being carried out if the temperature acquired between the catalytic purification member and the particulate filter is lower than a predetermined initiation temperature; the exhaust line comprises a vaporizer capable of vaporizing the fuel injected upstream of the catalytic purification unit, and the method comprises, before the injection start-up step, a step of preheating an electric heating element fuel vaporizer and a first diagnostic step, said first diagnostic step comprising the following successive sub-steps: - acquire a magnitude representative of the electric current consumed by the electric heating element; stopping the regeneration process of the particle filter if said quantity representative of the electric current consumed is less than a predetermined threshold; the method comprises, after the step of starting the injection, a second diagnostic step, said second diagnostic step comprising the following successive sub-steps: at the end of a predetermined duration from the start of the injection acquiring a magnitude representative of the temperature between the catalytic purification member and the particulate filter; - interrupt the fuel injection into the exhaust line if said acquired temperature is outside a predetermined range.

According to a second aspect, the invention relates to a device for regenerating a particulate filter of a motor vehicle exhaust line, the exhaust line comprising a catalytic purification element placed upstream of the particulate filter, the regeneration device comprising: means for injecting a fuel in vaporized form into the exhaust line upstream of the catalytic purification unit; means for controlling the start of the fuel injection in vaporized form in the exhaust line upstream of the catalytic purification member; means for determining a quantity representative of the total amount of heat energy supplied by the exhaust gas at the inlet of the particulate filter since the start of the fuel injection; means for stopping the injection of the fuel in the vaporized form into the exhaust line when the total amount of heat energy supplied by the exhaust gas entering the particle filter since the start of the fuel injection is greater than a predetermined amount of heat energy. Other features and advantages of the invention will emerge from the detailed description given below, by way of indication and in no way limiting, with reference to the appended figures, in which: FIG. 1 is a diagrammatic representation of a exhaust line portion comprising a particle filter, and a regeneration device of said particulate filter; FIG. 2 is a diagram showing the main steps of a regeneration method of a particulate filter in accordance with the invention; and FIG. 3 is a diagram similar to that of FIG. 2 for an alternative embodiment of the method of the invention. The exhaust line 1 shown in Figure 1 is an exhaust line of a motor vehicle with a combustion engine. It typically comprises a turbocharger 3, a particulate filter 5, a catalytic purification member 7 placed upstream of the particulate filter, and a device 9 for regenerating the particulate filter 5. The exhaust line also comprises an envelope 11 in which are placed the catalytic purification unit 7 and the particulate filter 5. The envelope 11 defines an exhaust gas inlet 13 and an exhaust gas outlet 15, the exhaust gases flowing through the envelope 11 from the inlet 13 to the outlet 15 through successively the catalytic purification member 7 and the particulate filter 5.

The exhaust line further comprises a connecting duct 17 connecting an exhaust gas outlet 19 of the turbocharger to the inlet 13 of the casing housing the particulate filter. An exhaust gas inlet 21 of the turbocharger is connected to a manifold 23 capturing the exhaust gas at the outlet of the combustion chambers of the engine 25 of the vehicle.

Other equipment may be interposed between the collector 23 and the turbocharger 3. The outlet 15 of the envelope housing the particle filter is connected to the cannula of the exhaust line. The exhaust gases are released into the atmosphere by the cannula. Other equipment, for example a silencer, can be interposed between the outlet 15 and the exhaust cannula. The regeneration device 9 of the particulate filter comprises a fuel vaporizer 27, a pipe 29 for supplying the vaporizer with fuel, a fuel metering element 31 supplying the vaporizer, a temperature sensor 33 situated between the purification member catalytic converter 7 and the particulate filter 5, and a computer 35. The device may also optionally comprise a fuel pressure sensor 37 upstream of the metering element 31, a valve 39 for closing off the pipe 29 and the evaporator emptying means referenced 41. The vaporizer 27 is mounted on the connecting pipe 17, and is located between the turbocharger 3 and the inlet 13 of the casing housing the particulate filter. The vaporizer is of a type known in itself. The vaporizer comprises an electric heating element 43 and a body 45 provided with a fuel inlet 47.

The inlet 47 is connected to the fuel supply pipe 29. The body 45 is rigidly fixed to the connecting pipe 17. It comprises a fuel vaporization chamber, not shown, in which is located the active part of the heating element 43. The fuel inlet 47 opens into the vaporization chamber. The body 45 also defines a fuel vapor entrainment chamber communicating with the vaporization chamber. The driving chamber is placed inside the conduit 17 and has an inlet for the exhaust gas, and an outlet for the exhaust gas loaded with fuel vapor. The fuel vaporized by the heating element 43 in the vaporization chamber enters the drive chamber and is driven by the exhaust gas stream that sweeps the drive chamber. The supply line 29 connects the vaporizer to an element of the motor vehicle where the fuel is available under pressure. This element can be for example the low-pressure stage 47 of the fuel pump supplying the engine of the vehicle.

The metering element 31 is for example a fast solenoid valve, interposed on the supply line 29 between the vaporizer 27 and the fuel pump. The solenoid valve 31 is driven by the computer 35 so as to open and close at a determined frequency, each opening having a fixed duration. The frequency and the duration of opening depend on the mass flow rate of fuel to be sent to the vaporizer 27. For example, the solenoid valve 31 can open at a frequency of between 4 and 20 Hertz, with opening times included between 1.4 ms and 15 ms. The mass flow rate of fuel passing through the metering element 31 is typically between 0.1 and 2.7 kg / h. The maximum mass flow rate possible through the metering element is about 20 kg / h of fuel, this mass flow being obtained by keeping the metering element 31 constantly open. The shut-off valve 39 is an on-off valve, capable of cutting off the flow of fuel in the supply line 29 or allowing it. It is controlled by the computer 35. It is placed upstream of the metering element 81. The temperature sensor 33 is mounted on the casing 11 housing the particulate filter and the catalytic purification member. The sensor 33 is able to measure the temperature of the exhaust gas in the space 49 separating the catalytic purification unit 7 from the particle filter 5. The sensor 33 is electrically connected to the computer 35 and informs the computer 35 on the temperature exhaust gas between the member 7 and the particulate filter 5. The emptying system 41 comprises a return conduit 51 connecting the supply line 29 to the fuel tank of the vehicle 52, and a solenoid valve 53. The line 51 is connected to the pipe 29 between the metering element 31 and the vaporizer 27. The solenoid valve 53 is placed on the return line 51, and is selectively able to close off or disengage the line 51. solenoid valve 53 is controlled by the computer 35.

The computer 35 is for example integrated in the computer controlling the engine of the vehicle. The regeneration device of the particulate filter also comprises means for acquiring a quantity representative of the flow of exhaust gas produced by the engine of the motor vehicle, and the temperature of said exhaust gas at the outlet of the combustion chambers. These means are adapted to estimate the mass flow produced by all the combustion chambers of the engine and entering the exhaust line, and the temperature of the gases from the different combustion chambers once mixed. The regeneration device of the particulate filter furthermore comprises means for acquiring a quantity representative of the electric current consumed by the electric heating element 43 of the vaporizer, and means for acquiring quantities representative of the temperature of the engine coolant, the motor load of the engine speed, and possibly other operating parameters such as the engine intake air temperature or the total duration of use of the catalyst.

The various means making it possible to acquire quantities representative of the exhaust flow, of their temperature, and of the electric current consumed by the vaporizer may comprise sensors. Alternatively, the representative quantities can be retrieved in a computer or in a control system of the motor vehicle.

The regeneration method of a particulate filter using a device 9 without a drainage system 41 will now be described with reference to FIG. 2. The regeneration method of the particulate filter is started by the calculator 35, when he considers it necessary. The computer 35 starts the regeneration of the particulate filter when, for example, the vehicle has traveled a certain number of kilometers since the previous regeneration. Alternatively, the computer can start the regeneration of the particulate filter when the engine has been running for a certain number of hours since the previous regeneration. The computer can still start the regeneration according to the evolution of operating parameters of the engine or the exhaust line. The computer 35 will then acquire a magnitude representative of the engine coolant temperature (Tmotor), and compare this temperature to a predetermined threshold. If the acquired temperature is below the temperature threshold, regeneration of the particulate filter is not started. On the other hand, if the temperature of the acquired coolant is greater than the temperature threshold, the computer 35 acquires, via the temperature sensor 33, a quantity representative of the temperature of the exhaust gases between the catalyst 7 and the filter with particles 5 (Tcata). It compares it to a predetermined boot temperature (Tamper). If the temperature of the exhaust gas acquired is greater than the ignition temperature, the computer 35 commands to trigger the power supply of the heating member 43 of the vaporizer (preheated). The initiation temperature is typically between 150 and 200 ° C. If the temperature of the exhaust gases acquired by the sensor 33 is less than the ignition temperature, the computer 35 requests the engine control computer to control the post-injections of fuel in the combustion chambers of the engine. These post-injections are performed slightly after the main injection of fuel into the combustion chambers. Thus, they are made a few degrees crankshaft after the dead point corresponding to the main fuel injection. The post-injections are performed under conditions such that the fuel injected during the post-injections burns at least partially in the combustion chambers and increases the temperature of the exhaust gas discharged to the exhaust line. Post-injections therefore make it possible to progressively increase the temperature of the exhaust gases. Once the temperature of the exhaust gas read by the sensor 33 exceeds the priming temperature, the electric heating element is electrically powered during a preheating period of predetermined duration. Once the preheating is complete, the computer 35 controls the start of the fuel vaporization in the exhaust line. It activates the metering element 31, setting a setpoint corresponding to a predetermined fuel mass flow rate. This mass flow rate results in an opening frequency of the metering element 31, that is to say an injection frequency, and an injection duration at each opening of the metering element. In the case where the regeneration device comprises a sensor for measuring the fuel pressure upstream of the metering member 31, the computer 35 determines the injection time as a function of the pressure acquired by the sensor 37. mass flow of fuel supplying the vaporizer 27 is determined at each time step by the computer 35 using maps, tables or by calculation. The flow setpoint is determined based essentially on the engine load and the engine speed. For this purpose, the computer 35 acquires magnitudes representative of the load and the engine speed, for example in the engine control computer of the vehicle. The flow setpoint can be weighted by a correction depending on the engine intake air temperature and / or the engine cooling water temperature, and / or other engine parameters such as for example the evolution of the operating parameters of the fuel injectors in the combustion chambers of the engine or the total duration of use of the catalyst ... etc. The maps used to determine the fuel flow rate to be sprayed, as well as the correction tables, come from tests of the engine and the bench exhaust system, or tests on board road vehicles. The fuel then flows along the feed pipe 29 from the stage 47 to the vaporizer 27, at a rate metered by the element 31. The fuel enters the vaporization chamber, heats up and is vaporized in contact with the active portion of the electric heating element 43. The fuel vapors enter the vaporizer drive chamber 27 and are driven to the catalytic purification element 7 by the exhaust gas from the turbocharger 3 The exhaust gases mixed with the fuel vapors ignite in contact with the catalytic purification unit 7 and create an exotherm. The temperature of the exhaust gas in the space 49, that is to say downstream of the catalytic purification unit 7, is thus increased and is higher than upstream of the member 7. The exhaust gas exhaust at high temperature then enter the particulate filter and heat it. The particulate filter is thus maintained at a high temperature, so that the soot particles deposited on the upstream side of the particulate filter burn and are converted to carbon oxides. The gaseous carbon oxides pass through the particulate filter and are released into the atmosphere by the exhaust cannula. After starting the injection of fuel in the form of steam into the exhaust line, the computer 35 periodically acquires quantities representative of the mass flow rate of the exhaust gas produced by the engine of the vehicle, and the temperature of the exhaust gases. exhaust between the catalytic purification member and the particulate filter. Said temperature is read by the sensor 33. The computer, at each time step k, calculates the amount of heat energy Ek supplied by the exhaust gas at the inlet of the particulate filter.

It carries out the totaling of the heat energy carried by the exhaust gases at the inlet of the particulate filter since the start of the injection by adding the quantity of energy Ek supplied at step k to the sum of the quantities of energy supplied. in steps 1 to k-1. The heat energy supplied at step k is calculated using the formula: Ek = mk CpTk where Ek is the heat energy provided by the exhaust gas at the step k at the inlet of the particulate filter, mk is the mass of exhaust gas produced by the engine at step k, Cp is the heat capacity of the exhaust gas and Tk is the temperature read by the sensor 33 at step k.

When the total quantity of heat energy supplied by the exhaust gas at the inlet of the particulate filter since the start of the fuel injection is greater than a predetermined amount of heat energy, the vaporization of fuel in the line of exhaust is stopped by the computer 35. It also controls the closing of the solenoid valve 39.

Said predetermined amount of heat energy results from prior tests. This amount of heat energy is the estimated amount of energy required to completely regenerate the particulate filter, i.e. to burn substantially all the soot particles deposited on the particulate filter. This amount is determined by calculation and / or tests, depending on the engine and the characteristics of the particulate filter. After stopping the vaporization, the computer 35 commands the heating element 43 to remain energized for a predetermined post-heating time. Once the predetermined period of post heating has elapsed, the computer 35 controls the stopping of the power supply of the heating element 43. The regeneration of the particle filters is then complete.

In parallel with the regeneration method described above, the computer 35 implements several programs for monitoring the operation of the regeneration device 9. Before starting the injection of fuel into the exhaust line, the computer 35 acquires a quantity representative of the electric current consumed by the electric heating element. If the representative quantity is less than a predetermined threshold, the regeneration process of the particulate filter is stopped. The calculator 35 interprets this result as meaning that the electric heating element is non-functional.

Furthermore, after the step of starting the vaporization, the computer 35 periodically acquires a magnitude representative of the temperature of the exhaust gas at the output of the vehicle engine. It retrieves for example this quantity in the computer controlling the engine of the vehicle. The computer 35 compares this acquired temperature with a predetermined maximum temperature.

The predetermined maximum temperature is for example 600 ° C. If the temperature acquired is greater than the predetermined maximum temperature, the computer controls the temporary interruption of the injection of fuel into the exhaust line, until the temperature has fallen below the predetermined maximum temperature. On the other hand, the computer 35 continues to totalize the total amount of heat energy provided by the exhaust gas at the inlet of the particulate filter. Indeed, when the exhaust gas has a temperature greater than the predetermined maximum temperature, the regeneration of the particulate filter occurs spontaneously, without having to increase the temperature of the exhaust gas, creating an exotherm by fuel injection in upstream of the catalytic purification unit. As illustrated in FIG. 2, after starting the injection of fuel into the exhaust line, the computer 35, at the end of a predetermined duration from the start of the injection (timing), acquires a quantity representative of the temperature downstream of the catalytic purification member and upstream of the particulate filter. This magnitude is provided by the sensor 33. The computer 35 compares the acquired temperature with predetermined values T1 and T2 delimiting a predetermined temperature range. If the acquired temperature is outside the range, the computer 35 commands to interrupt the vaporization and activates a diagnostic strategy. The safety solenoid valve 39, if it exists, is closed. The power supply of the heating element 43 is interrupted.

During the vaporization of fuel in the exhaust line, the computer 35, when the device 9 comprises a pressure sensor such as 37, acquires a magnitude representative of said fuel pressure in the supply line. The computer 35 then compares the acquired value with values Pmin and Pmax defining a pressure interval. If the pressure acquired is outside the range, the computer 35 interrupts the vaporization. The isolation valve 39 is closed and the power supply of the heating element 43 is interrupted. When the vehicle is at a stabilized operating point, the computer 35 can correct the fuel flow setpoint given to the member 31. By stabilized operating point is meant a period during which the vehicle moves at a speed substantially constant for a duration greater than a predetermined time. The computer 35 acquires a magnitude representative of the temperature between the catalytic purification member and the particulate filter, and compares it with a theoretical value of the catalyst outlet temperature. If this value is lower than the theoretical temperature, then the flow setpoint during the next regeneration will be increased by a quantity determined according to the difference between the acquired temperature and the theoretical temperature. Conversely, if the temperature acquired is greater than the theoretical temperature, then the fuel flow rate instruction injected will be reduced by a predetermined amount. Referring now to FIG. 3, an alternative embodiment of the regeneration method according to the invention, corresponding to a device for regenerating the particulate filter comprising means for emptying the fuel towards the reservoir, will now be described.

The procedure is identical to that of FIG. 2, until the stage during which the vaporization is stopped. As indicated above, the heating element is kept energized for a post-heating period of predetermined duration. After this period of post heating, that is to say after stopping the power supply of the heating element 43, the computer 35 controls the opening of the solenoid valve 53, so that the fuel remaining in the vaporizer flows gravity into the fuel tank. The vaporizer chamber of the vaporizer and the portion of the supply line 29 located downstream of the junction point between the return line 51 and the line 29 can thus be emptied. The draining solenoid valve is closed again after a period of time. predetermined. Alternatively, the solenoid valve can be opened immediately after stopping the vaporization and remain open during the post-heating period of the electric heating element 43. The method described above has many advantages. Since it comprises a step of determining a magnitude representative of the total amount of heat energy provided by the exhaust gas at the inlet of the particulate filter since the start of the fuel injection, the step of to stop the injection of the fuel in vaporized form being implemented when the total amount of heat energy provided by the exhaust gas at the inlet of the particulate filter since the start of the fuel injection is greater than a quantity of predetermined heat energy, the method allows to regenerate the particulate filter more efficiently. Indeed, the regeneration of the particulate filter is stopped when a predetermined amount of heat has been added to the particulate filter. This takes into account the variations in engine speed and load during the regeneration phase of the particulate filter. These variations have a strong influence on the temperature and the flow rate of the exhaust gases arriving at the particulate filter and therefore on the efficiency of the regeneration of this filter. The fuel flow supplying the vaporizer is determined at each time step in a very simple manner, typically by mapping according to the load and the engine speed. This mapping can also take into account other parameters, as indicated above, when one wants to refine the estimate of the fuel flow rate setpoint. It should be noted that the flow setpoint is independent of variations in the temperature of the exhaust gas downstream of the catalytic purification unit and downstream of the particulate filter. Thus, the adaptation of the flow setpoint to the operating conditions of the engine is fast and efficient. The fact of being able to control a post-injection of fuel in the combustion chambers of the engine makes it possible to increase the temperature of the exhaust gases quickly and efficiently. The method provides for multiple diagnostic procedures, to recognize the case where the heating element of the vaporizer is faulty, the case where it is not possible to obtain an exotherm at the catalytic purification member, or the case where the fuel pressure in the supply line is unsuitable. Furthermore, the method provides a self-correction possibility to correct the mass flow of fuel to be injected into the vaporizer for the next regeneration. The regeneration device may comprise draining means which make it possible to prevent fouling of the lines and the vaporizer in the long term by quantities of fuel stagnant in the vaporizer or in the supply line between the regeneration periods. The regeneration device can be used on new vehicles as on used vehicles. It adapts to most exhaust lines, since these generally include a single temperature sensor, mounted between the catalytic purification member and the particulate filter. The implementation of the regeneration process requires few additional equipment, and is therefore inexpensive.

The method and the regeneration device may have multiple variants. The temperature sensor is preferably mounted between the catalytic purification member and the particulate filter. However, it could be placed either upstream of the catalytic purification unit or downstream of the particulate filter.

In this case, the calculation formulas must be adapted to deduce from the measured temperature the temperature value used in the calculation formulas.

In a non preferred variant, the regeneration device may not include a temperature sensor. In this case, all exhaust gas temperatures are estimated solely by calculation. The injected fuel flow could be estimated from the engine load alone or from the engine speed alone, or from other parameters. In a non preferred variant, the injected fuel flow can also be taken constant. The injection of fuel into the exhaust line may not be interrupted if the exhaust gas temperature at the engine outlet is greater than 600 ° C, or more generally at the maximum temperature limit discussed above. It is possible that the regeneration process does not provide that a post-fuel injection is performed in the combustion chambers of the engine to increase the temperature of the exhaust gas. In this case, if the temperature of the exhaust gas measured by the sensor 33 is lower than the ignition temperature, the regeneration process is simply stopped, waiting for an increase in the temperature of the exhaust gas. In non-preferred variants of the regeneration method, there is no diagnostic procedure such as those described above.

Moreover, the post-heating period of the electric heating element of the vaporizer is optional. The fuel injected into the exhaust line may not come from the fuel injection pump into the combustion chambers of the engine. In this case, the regeneration device may comprise a metering pump whose suction is for example directly connected to the fuel tank. The pressure sensor disposed upstream of the metering member may be replaced by a pressure regulator adapted to regulate the fuel pressure reaching the dosing member. The method and device described above are particularly suitable for diesel-type thermal engines. Nevertheless, they can also be adapted to petrol engines equipped with particulate filters.

Claims (10)

REVENDICATIONS1. Process for the regeneration of a particulate filter (5) of a motor vehicle exhaust line (5), the exhaust line (1) comprising a catalytic purification element (7) placed upstream of the particulate filter (5), the method comprising the following steps: - starting an injection of a vaporized form fuel into the exhaust line (1) upstream of the catalytic purification member (7); stopping the injection of the fuel in vaporized form into the exhaust line (1) when the regeneration of the particulate filter (5) is complete; characterized in that it comprises a step of determining a magnitude representative of the total amount of heat energy provided by the exhaust gas at the inlet of the particulate filter (5) since the start of the fuel injection, the step of stopping the injection of the fuel in vaporized form being implemented when the total amount of heat energy provided by the exhaust gas at the inlet of the particulate filter (5) since the start of the injection of fuel is greater than a predetermined amount of heat energy. 2. regeneration method according to claim 1, characterized in that it comprises, after the step of starting the injection, a step of periodic acquisition of quantities representative of the flow of exhaust gas produced by the engine of the vehicle and the temperature of the exhaust gas between the catalytic purification unit (7) and the particulate filter (5), the total amount of heat energy provided by the exhaust gas at the inlet of the particulate filter (5) since the start of the fuel injection being calculated according to the acquired exhaust gas flow rates produced by the vehicle engine and the exhaust gas temperature between the catalytic purification member (7) and the particulate filter (5). 3. regeneration process according to claim 2, characterized in that the fuel is injected at a mass flow rate determined according to the load and / or engine speed of the motor vehicle. Regeneration process according to claim 3, characterized in that the exhaust gases have variable temperatures downstream of the catalytic purification unit (7) and downstream of the particulate filter (5), and in that said average mass flow rate is independent of variations in exhaust gas temperature downstream of the catalytic purification member (7) and downstream of the particulate filter (5). 5. regeneration method according to claim 4, characterized in that it comprises, after the step of starting the injection, a step of periodically acquiring a magnitude representative of the temperature of the exhaust gas output of the vehicle engine, the injection at a determined average mass flow rate is interrupted if the acquired temperature is greater than a predetermined maximum temperature. 6. regeneration process according to any one of the preceding claims, characterized in that it comprises, before the step of starting the injection, a step of acquiring a magnitude representative of the temperature between the organ catalytic purification unit (7) and the particulate filter (5), the fuel injection start-up step being carried out only if said acquired temperature is higher than a predetermined ignition temperature. 7. Regeneration process according to claim 6, characterized in that it comprises a step of performing fuel post-injections in the combustion chambers of the engine under conditions such that the fuel injected during the post-injections burns. at least partially and increases the temperature of the exhaust gas, said step of performing post-injections being carried out if the temperature acquired between the catalytic purification member (7) and the particulate filter (5) is lower at a predetermined priming temperature. 8. Regeneration process according to any one of the preceding claims, characterized in that the exhaust line (1) comprises a vaporizer (27) adapted to vaporize the fuel injected upstream of the catalytic purification member (7). , and in that the method comprises, before the step of starting the injection, a step of preheating an electric heating element (43) of the vaporizer (27) of fuel and a first diagnostic step, said first step diagnostic system comprising the following successive sub-steps: - acquiring a magnitude representative of the electric current consumed by the electric heating element (43); stopping the regeneration process of the particle filter (5) if said quantity representative of the electric current consumed is less than a predetermined threshold. 9. Regeneration method according to any one of the preceding claims, characterized in that it comprises, after the step of starting the injection, a second diagnostic step, said second diagnostic step comprising the following successive sub-steps. at the end of a predetermined time from the start of the injection, acquiring a quantity representative of the temperature between the catalytic purification element (7) and the particulate filter (5); - interrupt the injection of fuel into the exhaust line (1) if said acquired temperature is outside a predetermined range. 10. Device for regeneration of a particulate filter (5) of an exhaust line (1) of a motor vehicle, the exhaust line (1) comprising a catalytic purification member (7) placed upstream of the filter particulate filter (5), the regeneration device comprising: - means (27) for injecting a fuel in vaporized form into the exhaust line (1) upstream of the catalytic purification member (7); means (31, 35) for controlling the start of the injection of fuel in vaporized form into the exhaust line (1) upstream of the catalytic purification element; means (33, 35) for determining a quantity representative of the total quantity of heat energy provided by the exhaust gas at the inlet of the particulate filter (5) since the start of the fuel injection; means (31, 35) for stopping the injection of the fuel in vaporized form into the exhaust line (1) when the total amount of heat energy supplied by the exhaust gas at the inlet of the particulate filter (5) ) since the start of the fuel injection is greater than a predetermined amount of heat energy.