EP2776297A1

EP2776297A1 - Method for regenerating a particle filter for hybrid motor vehicles

Info

Publication number: EP2776297A1
Application number: EP12790619.6A
Authority: EP
Inventors: Christophe Colignon
Original assignee: Peugeot Citroen Automobiles SA
Current assignee: PSA Automobiles SA
Priority date: 2011-11-07
Filing date: 2012-10-25
Publication date: 2014-09-17
Also published as: RU2605798C2; WO2013068668A1; FR2982316A1; RU2014123377A; FR2982316B1; BR112014010312A2; CN103930327A

Abstract

The invention relates to a method for regenerating a particle filter, said particle filter being found in a gas exhaust circuit in relation to a combustion engine installed in a hybrid motor vehicle, according to said method, if regeneration is underway, the input temperature of the particle filter is measured continuously and the power train coordinator managing the traction modes of the vehicle will inhibit a first instance of stopping of the combustion engine at least if the measured temperature is lower than the first set point temperature (Tfirst stop), and if a first stop has not been inhibited, the power train coordinator will authorise the stopping of the heat engine as long as the temperature upstream of the particle filter is higher than a second set point temperature (Tupstream PF) depending on the load of the particle filter at the moment when the engine stop request is made.

Description

METHOD FOR REGENERATING A PARTICLE FILTER FOR

The invention is in the field of hybrid motor vehicles equipped with a combustion engine in connection with a gas exhaust system comprising a particulate filter. More particularly, the invention is in the field of pollution control processes for such motor vehicles, the combustion engine of which may be stopped during certain driving phases. [ooo2] Hybrid vehicles are equipped with several sources of motorization implementing energy sources that are implemented alternately. These alternative energy sources include fuels, petrol or diesel, and electric power.

[ooo3] Fuel-burning combustion engines emit solid particles, the removal of which is commonly achieved by means of a particulate filter that includes the exhaust gas system. The particulate filter is commonly associated with a catalyst device, which is placed upstream of the particulate filter in the direction of gas flow. Such a catalyst device is intended to clean the exhaust gas from the engine, prior to their passage through the filter in which the particles are trapped. The trapped particles are removed by burning at a temperature of the order of between 450 ° C. and 750 ° C., the low temperature range of less than 550 ° C. being possible only if the filter is said to have an additive, that is, if an additive such as ceria or iron is added to the fuel tank.

[ooo4] Even if the particulate filter is additive, to obtain such temperatures, these temperatures are generally higher than the temperatures of the exhaust gases of a diesel-type combustion engine, and means are therefore implemented. to increase the thermal of the engine, for example by calibrating the engine according to particular operating conditions, such as from a sub-calibration of the injections, and / or by regulating the intake pressure and / or the implementation of post-injections. The load of the motor is also likely to be increased by exploiting electric consumers whose implementation is regulated according to the needs.

[Ooo5] A problem specifically posed for hybrid vehicles lies in the shutdown of the combustion engine with which they are equipped when the hybrid vehicle uses an alternative source of energy for the operation of an auxiliary engine, an electric motor especially. With the stopping of the combustion engine, the temperature in the exhaust system falls sharply and there is no more gas flow in the exhaust line. In the case of an attempt to regenerate the particulate filter, this is very detrimental because either it delays the moment when the combustion of the particles will begin, or it will slow down this combustion (when it has already begun before one stop the engine), or it will stop it altogether. As a result, the simplest solution for preserving the regeneration of the particulate filter is to prevent the engine from stopping if regeneration has been requested by the particle filter controller.

[ooo6] However, such a solution can cause a "negative" impact on the driver who will not necessarily understand why his vehicle no longer works as a "hybrid", especially if he presses the button "Pure electric mode". In order to allow operation allowing the use of the electric mode, it is necessary to establish a strategy that minimizes the negative impacts of a thermal engine shutdown.

[ooo7] To avoid breaking the regeneration of the particulate filter in the event of engine shutdown, it has been proposed by the patent application FR2925938 to inject hot air into the exhaust system, by associating with this fuel injection operation to maintain an exotherm in the catalyst.

[ooo8] It has also been proposed by the document EP0987139 to adapt the management of the operation of the auxiliary engine as a function of the detected temperature of the catalyst. More particularly, the auxiliary motor provides a power supply which is corrected according to such a temperature detection, a lowering the temperature of the catalyst causing a reduction in the amount of auxiliary current supplied to minimize the assistance provided to the engine.

[Ooo9] It is also known from the patent application FR 2956878 a method of regeneration of a particulate filter comprises a gas exhaust system in connection with a combustion engine equipping a hybrid vehicle, according to which if a regeneration is in progress while a request for stopping the combustion engine is controlled following the activation of an alternative means of motorization of the vehicle, the temperature at the inlet of the particle filter is continuously detected; the detected temperature is compared with a first set temperature; and stopping the combustion engine at least if the sensed temperature is lower than the first set temperature, until at least the sensed temperature is greater than a second set temperature, in which case the Stopping the combustion engine is allowed. [ooi o] Thus, if the particulate filter is at a temperature above a first setpoint temperature, that is, if a regeneration is occurring and the particulate filter has a satisfactory thermal, then the filter will be allowed. shutdown of the engine. On the other hand, when the penalty generated by these stops becomes too great because of a temperature at the inlet of the particulate filter that is too low, the restart of the engine will be forced or the shutdown will be stopped.

The present invention relates to an improvement of the known process of patent application FR 2956878 so as to optimize the chances of regeneration of the particulate filter while minimizing the impact for the customer, and to keep at most a mode hybrid operation. It consists in adapting the regeneration strategy as a function of the soot mass: when the particulate filter is lightly filled with soot, we can afford to have a longer regeneration but the more the filter filled with particles, the more the need to have a short and effective regeneration increases. This object is achieved by a method of regeneration of a particulate filter that comprises a gas exhaust circuit in connection with a combustion engine. combustion of a hybrid vehicle, according to which if a regeneration is in progress then it is continuously detected the inlet temperature of the particulate filter and the coordinator GMP managing the traction modes of the vehicle, will inhibit a first stop of the combustion engine at least if the detected temperature is lower than the first setpoint temperature (the first stop), and if a first stop has not been inhibited, will allow a shutdown of the engine as long as the temperature upstream of the particulate filter is greater than one. second setpoint temperature (Tamont FAP) dependent on the charge of the particulate filter at the instant of the regeneration request. Advantageously, the first setpoint temperature and the second setpoint temperature are differentiated, by assigning the first setpoint temperature to an initial stopping of the combustion engine between two starting phases of the vehicle and the second setpoint temperature. an authorization to stop the engine when the measured temperature of the particulate filter is satisfactory with regard to its regeneration.

In a preferred variant of the invention, the soot load is also taken into account to specifically authorize an area where the traction is only obtained by the electrical means (PET zone for Pure Electric Traction), with for example for heavy soot loads, a complete ban on passage through the PET zone. In other words, the control laws of the hybrid mode do not depend only typically the speed and torque requested by the driver and the battery charge but also the soot load.

In a variant, the prohibition of stopping the engine placed under the control of the first set temperature is furthermore dependent on a detection of the temperature outside the vehicle and on a comparison between this outside temperature detected and a set outdoor temperature. Thus, it takes into account the greater or lesser capacity of the outside air to cool the exhaust line. [0016] The subject of the invention is also a strategy for restarting the engine, which also takes into account the soot charge. and allows even to minimize the impact for the customer while allowing the regenerations to occur in good conditions.

Thus, following a stop of the thermal engine allowed during a regeneration phase of the particulate filter, according to a variant of the invention, it forces the restart of the engine when certain restart conditions are satisfied, said restart conditions. taking into account the soot charge at the regeneration start. Alternatively, the soot load is taken into account at the time of restarting.

In a variant, a restart condition is a temperature upstream of the particulate filter lower than a third temperature threshold said restart temperature threshold, said threshold restart temperature being adapted according to the soot load at the launch of regeneration or alternatively, depending on the soot load at the time of restart

In a variant, a restart condition chosen may also be a maximum duration of authorized stoppage of the engine, this maximum duration of stopping of the engine being corrected according to the soot load of the particulate filter at launch. regeneration or when restarting.

Advantageously, the input data for this maximum period takes into account the speed of the vehicle at the time when the engine has been stopped and the outside temperature, the soot load coming as a multiplying coefficient (less than 1). to reduce this maximum duration.

In a variant, a restart condition is a maximum duration allowed for the regeneration phase, said maximum duration for the regeneration being adapted according to the soot load at the start of regeneration or at the time of restarting.

When a restart of the engine is controlled following the validation of one of the restart conditions listed above, it is advantageous to opt for a level 2 strategy for regeneration assistance, in other words, if we have two levels of support for regeneration, with a second level more penalizing in terms of consumption, we go without delay, opt directly for the most penalizing level (but also the most efficient). For these different levels of strategy, reference is made in particular to patent EP 1281852, which describes specific injection strategies for the regeneration phases of a particulate filter, level 1 and level 2 (these level 1 and 2 strategies being of course distinct from the strategies implemented outside the regeneration phases).

Furthermore, following a restart of the engine, it is advantageous to carry out a request for activation of electrical consumers (which will induce an increase in the engine load, and therefore the temperature of the exhaust gas), said activation request being able to be stopped when the temperature upstream of the particulate filter reaches a critical temperature limit for the activation of the electrical consumers. Similarly, it will also be possible to opt for a strategy for charging a vehicle battery, a strategy that will be stopped when the temperature upstream of the particulate filter reaches a critical temperature limit for the charging strategy of a battery, said ceilings of critical temperature being adjusted according to the soot load at regeneration start or at the time of restarting.

According to a detailed description of the method proposed by the present invention, as soon as a regeneration of the particle filter is triggered, the supervisor of this regeneration (said FAP supervisor) informs the GMP coordinator whose primary role is to opt for operation "all heat engine", "all electric" or mixed according to for example the demand for speed and torque expressed by the driver (depending on the depression state of the accelerator pedal for example), and the electric charge available ..

This information will inhibit the transition to pure electric mode under certain conditions.

Thus, it continuously detects the inlet temperature of the particle filter, (said upstream temperature with reference to the direction of flow of gas in the exhaust circuit), the detected temperature is compared with a first set temperature; and it is forbidden to stop the combustion engine at least if the detected temperature is lower than the first set temperature T first stop, called Threshold Tamont FAP inhibition first stop. If the engine stop has not been inhibited, then the next engine stop requests can be satisfied as the temperature upstream of the particle filter does not fall below a limit value of feasibility of regeneration (second set temperature) Tamont FAP. It should be remembered that the GMP Supervisor will constantly seek to provide the requested rpm and torque while optimizing the vehicle's fuel consumption, and therefore, even if the first stop has been cleared, it will not necessarily be controlled by the supervisor. GMP if for example the couple asked at that moment is too important. If after descending under this second setpoint temperature, the upstream temperature FAP rises above this limit value then the engine stop is allowed again.

This second setpoint temperature is adjusted according to the mass of soot present in the particulate filter: the higher the soot load, the higher the threshold. For example, this threshold could be set at 400 ° C when the charge of the particulate filter is lower than its nominal load (the nominal load is understood to mean the load below which a regeneration is not normally controlled) at 430 ° C. when there is a nominal load of soot and 460 ° C as soon as the soot mass exceeds 1.5 times this nominal value.

The activation of the auxiliary engine being maintained and satisfactory conditions with respect to the regeneration of the particulate filter being obtained, stopping the combustion engine is allowed. Such satisfactory conditions correspond in particular to an appropriate temperature of the particulate filter with respect to a second setpoint temperature, preferably taking into account the external temperature and / or the vehicle speed measured during the initialization of the operation of the regeneration of the particulate filter. More particularly, the temperature of the particulate filter is sufficient with respect to the second setpoint temperature, which corresponds to a limit value of the feasibility of the regeneration, the rolling of the vehicle from the auxiliary engine alone is allowed. The use of the auxiliary motor only is nevertheless adapted from the coordinator who operates a predefined Pure Electric Traction (TEP) zone specific to the regeneration phases of the particulate filter with specific support points. This adaptation of the PET zone takes into account not only that a regeneration of the particulate filter is in progress but also of the soot charge of the particulate filter: the more soot in the filter, the more the PET zone will be reduced. For example, this PET zone could be zero as soon as the soot load exceeds 1.5 times the nominal value.

Preferably, the prohibition of stopping the engine placed under the control of the first set temperature is furthermore dependent on a detection of the temperature outside the vehicle and a comparison between this temperature. outdoor temperature detected and a set outdoor temperature. Thus, we take into account the greater or lesser capacity of the outside air to cool the exhaust line.

Stopping the engine has been authorized, there are several specific criteria for forced restart of the combustion engine after its order to stop by the coordinator. These specific criteria themselves depend on the soot charge and correspond, for example, to the following 3 cases of figures: · If the temperature measured upstream of the particulate filter is lower than a third set point, said restart temperature threshold, Threshold T upstream restart, then the restart of the combustion engine is forced. The value of Threshold Tamont FAP restart is adapted to the soot load of the FAP: the more particles there are without the filter, the higher the threshold will be. For example, this threshold could be fixed at 390 ° C when there are no particles in the FAP, at 420 ° C when there is a nominal load of soot and 450 ° C as soon as the mass of soot exceeds 1, 5 times the nominal value.

• If the stopping of the combustion engine is maintained during a first set duration considered too long, the PET operation is considered too long compared to this first duration, to not not mortgage the chances of effectively regenerating the particulate filter, it is necessary to restart the combustion engine. This case essentially corresponds to a security in the case where the information provided by the temperature sensor upstream of the particulate filter would be incorrect without the sensor itself being detected in default. This set duration is preferably read from a cartography according to the speed of the vehicle on the one hand (speed at the moment when the engine was stopped) and on the outside air temperature on the other hand because these two parameters affect the cooling speed of the exhaust line. This mapping is preferably further corrected according to the mass of soot present in the particulate filter: the more particles in the filter, the shorter the maximum stopping time. For example this threshold could be set to 1 minute when there are no particles in the FAP, to 45 seconds when there is a nominal load of soot and 20 seconds as soon as the soot mass exceeds 1, 5 times the nominal value.

• If the regeneration request lasts too long, the heat engine is immediately restarted and the combustion engine runs continuously until regeneration is complete or the driver turns off the ignition. This maximum regeneration time is derived from a curve that is a function of the percentage of soot already regenerated, the percentage of soot already regenerated being calculated continuously from the data of the supervisor FAP and is adapted as a function of the mass of soot present in the particulate filter: The more particle filter is loaded into particles, the shorter the duration. For example, this threshold could be set at 10 minutes when the particulate load is lower than the nominal load, 8 minutes when there is a nominal load of soot and 5 minutes when the mass of soot exceeds 1.5 times the nominal value.

Note that a regeneration under the nominal mass can be triggered when the driving conditions are very favorable compared to the conditions of "normal" driving of the driver taking into account the driving history of the driver.

When an engine restart request is started, the coordinator GMP restarts the engine. It will therefore have to opt for the most appropriate control-command strategy.

It is desirable that when such a restart is requested following the validation of a restart condition, it operates the engine according to a high level regeneration strategy for immediate assistance regeneration without delay. Regeneration of the particulate filter being initiated, the corresponding electrical consumers equipping the vehicle are also activated. By corresponding electrical consumers is meant, for example, electrical means that will contribute directly to the regeneration (for example heating means) but above all means available, not controlled by the driver, and whose activation will create an increase in demand. torque, and therefore indirectly the temperature of the exhaust gas. These available means will be for example electrical resistors (such as a heated windshield or a heated rear window).

When the temperature requirements of the particulate filter are reached, the electrical consumers are disabled to minimize the power consumption of the vehicle. When conditions deteriorate, activation of electrical consumers can be requested again.

The deactivation of the electrical consumers is preferably carried out as soon as the temperature upstream of the particulate filter exceeds a critical temperature limit for the activation of the electrical consumers.

This critical temperature limit for the activation of electrical consumers, beyond which the activation demand of electric consumers is inhibited, is itself advantageously dependent on the soot load of the particulate filter. For example this threshold could be set at 500 ° C when the load is lower than the nominal load, at 520 ° C when there is a nominal load of soot and 550 ° C as soon as the mass of soot exceeds 1, 5 times the nominal value. Activation may be requested again if the temperature upstream of the particulate filter falls below a floor threshold, which may also be selected depending on the soot load of the particulate filter, for example set at 460 ° C when there are no particles in the FAP, at 480 ° C when there is a nominal load of soot and 500 ° C as soon as the soot mass exceeds 1.5 times the value nominal.

In addition to or in substitution for the activation strategy of the electrical consumers, it is also possible to provide a strategy for recharging the battery. An example of a battery charging strategy is reproduced with the help of Figure 1 which presents a block diagram of a method according to the teaching of the patent application FR 2952974.

In a first step A, the amount of Estock storable energy is determined in the electrical storage unit. This is the amount of energy to bring to the electrical storage to ensure a complete recharge. This amount of storable energy 1 depends on the level of charge of the storer at the time of determination, but may also depend on environmental factors such as the outdoor temperature or the internal temperature of the storer.

In a second step B, the power to be supplied P1 to the storer is determined to provide the amount of storable energy Estock in a predetermined reference time Tmini.

In a comparison step C, the power to be supplied P1 and a predefined minimum power Pmini are compared.

Pmini and Tmini are values that can be defined in an engine control device, and can be adapted according to the application considered (position of the particle filter relative to the engine, length of the exhaust line, etc.). In a typical automotive application, the duration Tmini, necessary for the increase in the load of the engine to have an effect significant on the gas temperature at the inlet of the particle filter due to the thermal inertia at the exhaust is of the order of 120 to 180 seconds.

If the power to be supplied P1 is greater than or equal to the minimum power Pmini is provided to the storer power to provide P1 during the reference period Tmini in a step of increasing the load of the engine D;

If the power to be supplied P1 is less than the minimum power, the storekeeper is provided with the minimum power Pmini for a period of time to ensure the complete recharging of the storer, in a minimum increase step of the engine load thermal E.

In the context of the present invention, when the temperature upstream of the particulate filter reaches a critical temperature limit for the battery charging strategy, this strategy is inhibited. This temperature limit advantageously depends on the soot charge of the particulate filter. For example this ceiling can be set at 480 ° C for soot loads lower than the nominal load, at 500 ° C when there is a nominal load of soot and 550 ° C as soon as the mass of soot exceeds 1, 5 times the nominal value.

Conversely, the activation of the strategy can be controlled if the temperature upstream of the particulate filter falls below a floor value for the battery charging strategy. This floor value can likewise depend on the soot load of the particulate filter.

For example this floor can be fixed at 450 ° C for soot loads lower than the nominal load, at 460 ° C when there is a nominal load of soot and 500 ° C as soon as the mass of soot exceeds 1, 5 times the nominal value. Note that it is also advantageous to provide a degraded mode in case of failure of the measurement of the temperature upstream of the particle filter or the outside temperature. In this case, the engine stop strategies can no longer be applied. Thus, if a regeneration request occurs while one of these sensors is in fault, the heat engine must remain in position. normal operation as long as the fault is present. Any shutdown of the engine will be prohibited and pure electrical operation will be impossible.

The method proposed by the present invention makes it possible to optimize the regeneration operation of the particulate filter for a minimum overall implementation time. A better energy efficiency is obtained, the combustion engine being implemented simultaneously with the operation of the auxiliary engine only in case of request by the control means of the vehicle, calculator and / or coordinator in particular, on the basis of the measurement of particle filter temperature performed continuously and in real time. The engine load in the restart phases provides a reduced instantaneous dilution of fuel in the oil. The driver perceives the driving phases of the vehicle from the auxiliary engine alone, an authorization to stop the combustion engine being ordered when the regeneration of the particulate filter is obtained. Since the electrical consumers are inhibited according to the measurement of the temperature of the particulate filter, a gain in the electrical consumption of the vehicle is procured. Regeneration of the particulate filter is efficient, regardless of the state of charge of the latter, with a selective activation of the vehicle's energy resources, which is adapted to reduce energy losses.

Claims

A method of regenerating a particulate filter comprising a gas exhaust circuit in connection with a combustion engine fitted to a hybrid vehicle, according to which if a regeneration is in progress then the temperature at the inlet of the filter is continuously detected. particles and the coordinator GMP managing the vehicle traction modes, will inhibit a first stop of the combustion engine at least if the detected temperature is lower than the first set temperature (Tpremost stop), and if a first stop has not inhibited, will allow a stop of the engine as long as the temperature upstream of the particulate filter is greater than a second setpoint temperature (Tamont FAP) dependent on the charge of the particulate filter at the instant of the regeneration request

Method according to Claim 1, characterized in that the first setpoint temperature and the second setpoint temperature are differentiated, by assigning the first setpoint temperature to an initial stopping of the combustion engine between two starting phases of the vehicle. and the second setpoint temperature at a stop authorization of the engine when the measured temperature of the particulate filter is satisfactory with respect to its regeneration.

Process according to any one of the preceding claims, characterized in that the said prohibition of stopping the engine placed under the control of the first set temperature is furthermore dependent on the detection of the outside temperature at the vehicle and a comparison between this detected outdoor temperature and a set outdoor temperature.

Process for the regeneration of a particulate filter, according to any one of the preceding claims, characterized in that following a shutdown of the heat engine authorized during a regeneration phase of the particulate filter, the restarting of the engine is forced when certain restart conditions are satisfied, said restart conditions taking into account the soot load at the regeneration start or at the moment of restarting.

A method of regenerating a particulate filter, according to claim 4, characterized in that a restart condition is a temperature upstream of the particulate filter lower than a third temperature threshold said restart temperature threshold, said temperature threshold of restart adapted to the soot load at regeneration start or restart

A method of regenerating a particulate filter according to any one of claims 4 to 5, characterized in that a restart condition is a maximum duration of stopping the heat engine, the maximum time corrected according to the load in Particulate filter soot at regeneration start or at restart.

A method of regenerating a particulate filter, according to claim 6, characterized in that said maximum duration before correction is a function of the speed of the vehicle at the time the engine was stopped and the outside temperature.

Process for the regeneration of a particulate filter, according to any one of claims 4 to 7, characterized in that a restart condition is a maximum duration allowed for the regeneration phase, said maximum duration for the regeneration being adapted to function of the soot load at regeneration start or at restart time

A method of regenerating a particulate filter according to any one of claims 4 to 8, characterized in that when a restart is requested following the validation of a restart condition, the engine is operated according to a high level regeneration strategy.

Process for the regeneration of a particulate filter according to any one of Claims 4 to 9, characterized in that when a restart is requested following the validation of a restart condition, electrical consumers and / or strategy of recharging a battery, said activation being stopped when the temperature upstream of the particulate filter reaches a critical temperature limit for the activation of electrical consumers or temperature ceiling critical for the battery charging strategy, said Critical temperature limits are adjusted according to the soot load at the regeneration start or at the restart time