This patent application claims priority from Italian patent application no. 102025000007068 filed on April 2, 2025, the entire disclosure of which is incorporated herein by reference.

The present invention relates in general to the field of internal combustion or thermal engine management, in particular the estimation of the rate of combustion or oxidation of particulate matter in the particulate filter for internal combustion engines of vehicles with thermal or hybrid propulsion, in particular in case of high temperature at the particulate filter.

The present invention relates to a vehicular control system and a computer program product or software for estimating the rate of combustion or oxidation of particulate matter in a particulate filter of a vehicle, in particular a vehicle with thermal or hybrid propulsion.

The present invention has application in any type of road vehicle, whether it is used to transport people, such as a passenger car, bus, motor home, etc., or to transport goods, such as an industrial vehicle (truck, tractor-trailer, etc.) or light or medium-heavy commercial vehicle (van, van-van, cruiser, etc.).

As is well known, in internal combustion engines equipped with a Gasoline Particulate Filter (GPF), e.g., in vehicles with thermal or hybrid propulsion, it is important to know the concentration of oxygen in the exhaust gas entering the particulate filter as well as the flow rate at which this oxygen enters the said particulate filter.

Figure 1 schematically shows a vehicle V, for example with thermal or hybrid propulsion, comprising a vehicular powertrain GM comprising a propulsion unit P, for example thermal or hybrid type, and a transmission system T interposed between the propulsion unit P and the drive wheels W of the vehicle V. In particular, the propulsion unit P comprises at least one internal combustion engine, also referred to as a thermal engine, MT.

The vehicle V also comprises vehicular components CV, the latter comprising at least one valve VF in particular a throttle valve designed to allow upstream regulation of the internal combustion engine MT of the amount of air trapped in the cylinders. In addition, as shown in Figure 1, the vehicular components CV comprise:

• an air filter FA designed to filter air entering the vehicle V;
• a compressor C connected to the air filter FA and designed to receive the filtered air to compress it; and
• a cooling system or cooler CL connected to compressor C and the valve VF and designed to perform cooling of the compressed air coming from compressor C.

The vehicle V also comprises exhaust components CS, which are connected to the internal combustion engine MT and here comprise a supercharger turbine T, designed to employ the exhaust gas produced by the internal combustion engine MT to propel the compressor C of the vehicle V to increase its rotational speed and to acquire air from the outside and supply compressed air to the internal combustion engine MT to allow more fuel to be burned; and a catalytic converter TWC, the latter being connected to the supercharger turbine T, designed to convert the major pollutants in the exhaust gas (in particular, hydrocarbons, carbon monoxide and nitrogen oxides) into less polluting gases. According to one aspect of the present invention, the exhaust components CS also comprise the particulate filter GPF, which is connected to the catalytic converter TWC and designed to filter particulate matter emitted by the internal combustion engine MT.

It is known that, in order to perform combustion or oxidize a mass of particulate matter or soot in the particulate filter GPF, the amount of oxygen to be supplied for soot combustion is typically provided during a phase of operation of the internal combustion engine MT called Deceleration Fuel Shut Off (DFSO), in which the required torque is essentially zero (in particular, the accelerator pedal of vehicle V is completely released) and fuel is not injected into the combustion chamber of the same vehicle V so that a non-negligible amount of air passes through the combustion chamber, exhaust, catalytic converter TWC and the particulate filter GPF, thus achieving the above-mentioned oxidation.

Methods and systems are known to control the rate of combustion or oxidation of particulate matter in the particulate filter GPF.

The Applicant has seen that the known solutions are amenable to improvement.

In particular, current models for estimating soot combustion rate trends in the particulate filter GPF predict that the particulate combustion rate is positive (i.e., the particulate is burning) only as long as the internal combustion engine MT is in the DFSO phase or in the shutdown phase, and is zero during the remaining operating phases of the internal combustion engine MT. Therefore, the current models do not consider operating points of the internal combustion engine MT wherein the phenomena of feeding and simultaneous combustion of particulate matter occur, without there being a DFSO phase. In this regard, the Applicant noted that particulate matter can also be burned in the particulate filter GPF due to the oxygen created within the catalytic converter TWC, i.e., at high temperatures, e.g., greater than 800°C, and with high exhaust gas flows, during fuel injection; in addition, additional oxygen is generated as a reaction product from the dissociation reaction of carbon dioxide into carbon monoxide and oxygen, thus resulting in a greater presence of oxygen, which leads, therefore, to greater oxidation/combustion of particulate matter.

In addition, particulate matter, which comprises carbon in its composition, can be further combusted through a Boudouard reaction, where carbon dioxide and carbon are the reactants and carbon monoxide is the reaction product; such a reaction can take place in the presence of a high amount of carbon (i.e., with a high level of particulate matter) and generally for thermal combustion engines MT with stoichiometric lambda equal to one and lower carbon monoxide emissions. In more detail, the aforementioned Boudouard reaction is favoured under high load and high engine speed operating conditions due to the high carbon dioxide flux and high temperature of the exhaust gas produced.

In addition, it is known to perform particulate combustion during the shutdown of the internal combustion engine MT, such as during Start&Stop events, which, however, do not allow the implementation of effective soot combustion reaction control strategies.

In addition, as anticipated above, the production of high amounts of oxygen can cause the particulate combustion reaction if the catalytic converter TWC has a low Oxygen Storage Capacity (OSC) and not allow the conversion of the total pollutants produced. In fact, the free oxygen produced can pass from the catalytic converter TWC to the particulate filter GPF in the case of high space velocity (defined in particular as the ratio of the total volumetric exhaust gas flow to the volume of the catalytic converter TWC); this results in a reduction of the time required for the conversion of the pollutants produced in the catalytic converter TWC, and, therefore, the free oxygen will be used for the combustion of particulate matter.

Therefore, the currently known methods and systems do not allow accurate control of the rate of combustion or oxidation of particulate matter, because, as explained above, there are several factors that contribute to substantial changes in the trend prediction produced by the known methods and systems.

Accordingly, it is the purpose of the present invention to make available a vehicular control system and related software for estimating the rate of combustion or oxidation of particulate matter in a particulate filter of a vehicle, in particular a vehicle with thermal or hybrid propulsion, even more in particular in case of high temperature at the particulate filter which will enable at least partial solutions to the problems that plague the solutions of the known art.

According to the present invention, a vehicular control system and related software are provided for estimating the rate of combustion or oxidation of particulate matter in a particulate filter of a vehicle, in particular a thermal-propelled vehicle or a hybrid vehicle, even more in particular in case of high temperature at the particulate filter, as claimed in the appended claims.

• Figure 1 schematically shows a vehicle comprising an internal combustion engine including exhaust components.
• Figure 2 schematically shows a diagram of a method for estimating the rate of combustion or oxidation of particulate matter in a particulate filter of a vehicle according to the present invention.
• Figure 3 schematically shows a diagram of a method for estimating a quantity related to the combustion rate of particulate matter in a particulate filter of a vehicle when fuel is injected according to the present invention.
• Figure 4 schematically shows a diagram of a method for estimating a quantity relative to the combustion rate of particulate matter in a particulate filter of a vehicle at elevated temperatures according to the present invention.

The present invention will now be described in detail with reference to the attached figures to enable a skilled person to realize and use it. Various modifications to the described embodiments will be immediately apparent to skilled persons, and the generic principles described can be applied to other embodiments and applications without departing from the protective scope of the present invention as defined in the appended claims. Therefore, the present invention should not be considered limited to the embodiments described and illustrated, but should be accorded the broadest scope of protection consistent with the features described and claimed.

Where not otherwise defined, all technical and scientific terms used herein have the same meaning commonly used by persons of ordinary experience in the field pertaining to the present invention. In case of conflict, this description, comprising the definitions provided, will be binding. Furthermore, the examples are provided for illustrative purposes only and as such should not be considered limiting.

In particular, the block diagrams included in the attached figures and described below are not intended as representations of structural features, i.e., constructional limitations, but are to be interpreted as representations of functional features, i.e., properties that are intrinsic to the devices and defined by the effects obtained, i.e., functional limitations and that can be implemented in different ways, thus in a way that protects the functionality of the same (ability to function).

In order to facilitate the understanding of the embodiments disclosed here, some specific embodiments will be referred to and a specific language will be used to disclose them. The terminology used herein is intended to disclose only particular embodiments, and is not intended to limit the scope of the present invention.

To summarize, the present invention relates to a vehicular control system and a related computer program product or software designed to estimate the particulate load in a vehicle's particulate filter by updating the calculated value using preset models even when the vehicle's internal combustion engine is fuelled, thus without waiting for a DFSO phase.

In the following, reference is made to a thermal- or hybrid-powered vehicle similar to the one shown in Figure 1; therefore, in the following and without any loss of generality, reference will be made to the thermal- or hybrid-powered V vehicle shown in Figure 1 and its references.

Figure 2 schematically shows a vehicular control system S for estimating the rate of combustion or oxidation of particulate matter in the particulate filter GPF in the vehicle V; in particular, with particular reference to Figure 3, the vehicular control system S is designed to:

• acquire a model of soot combustion rate in the particulate filter GPF, referred to as GPF_Soot_Load_Rate_Mdld in the following, and a model of soot load regeneration combustion rate in the particulate filter GPF, referred to as GPF_SL_Regen_Burn_Rate_Mdld in the following;
• acquire quantities indicative of exhaust oxygen concentration mass flow Exh_O2_Mass_Flow, soot load in the particulate filter GPF, denoted hereafter as GPF_Soot_Load, and a temperature of the particulate filter GPF, referred to as GPF_Temp in the following;
• determine a soot combustion rate in the particulate filter GPF wherein there is excess oxygen to conduct the soot combustion reaction, denoted below as GPF_Soot_Burn_Rate_Firing_Lean and indicative of conditions wherein, for example, there is a dissociation reaction leading to an increase in the amount of oxygen available, based on the mass flow of exhaust oxygen concentration Exh_O2_Mass_Flow, the soot load in the particulate filter GPF GPF_Soot_Load, and the temperature of the particulate filter GPF GPF_Temp; e
• determine the actual soot combustion rate in the particulate filter GPF based on the soot combustion rate model in the particulate filter GPF GPF_Soot_Load_Rate_Mdld, of the soot load regeneration combustion rate model in the particulate filter GPF GPF_SL_Regen_Burn_Rate_Mdld and the soot combustion rate model in the particulate filter GPF in case of excess oxygen for conducting the particulate combustion reaction GPF_Soot_Burn_Rate_Firing_Lean, in particular by means of an addition module ADD.

It is noted that the value of the temperature of the particulate filter GPF can be either the temperature at the inlet of the particulate filter GPF or the internal temperature of the particulate filter GPF, depending on the type of layout of the particulate filter GPF, the vehicle V, and the characteristics of the internal combustion engine MT.

Furthermore, according to one aspect of the present invention, the soot combustion rate pattern in the particulate filter GPF GPF_Soot_Load_Rate_Mdld, and the soot load regeneration combustion rate pattern in the particulate filter GPF GPF_SL_Regen_Burn_Rate_Mdld are predetermined by the system S, for example, based on outputs provided by sensors and/or control logic integrated in the gas exhaust system and engine control unit of the vehicle V.

In particular, with reference to Figure 3, in order to determine the soot combustion rate in the particulate filter GPF in case of excess oxygen for conducting the particulate combustion reaction GPF_Soot_Burn_Rate_Firing_Lean, the system S is designed to:

• verify (block S1) that vehicle V is in a phase wherein it is fuelled, i.e., vehicle V is not in DFSO mode;
• verify (block S2) that the oxygen concentration at the inlet to the particulate filter GPF is greater than or equal to a predetermined threshold value, referred to below as WRO2_US_Firing_Thr, i.e., that the mixture of air and soot is poor or lean (i.e., there is a greater amount of oxygen than the amount of soot present).

In more detail, the system S is designed to verify that the vehicle V is in a different condition than the DFSO condition, i.e., when the V vehicle is not fuelled, wherein, for example, there is both fuelling and particulate combustion. In particular, with reference to block S1 in Figure 3, system S is designed to verify that a DFSO activation command is different from one, i.e., does not occur.

In addition, the phases shown with reference to block S2 are indicative of whether the mixture of air and fuel at the particulate filter GPF, shown in the following as an oxygen quantity value WRO2_11_Lambda, is greater than or equal to the predetermined threshold value WRO2_US_Firing_Thr, received by the system S (block S4). In this regard, with reference to Figure 1, the vehicle V is equipped with a sensory system WRO2, DSO2 designed to generate outputs indicative of quantities related to the amount of oxygen entering the particulate filter GPF of vehicle V; in particular, the sensory system WRO2, DSO2 comprises a first and a second oxygen sensor WRO2, DSO2 arranged upstream and downstream of the catalytic converter TWC, respectively, and thus designed to monitor the flow of oxygen entering the particulate filter GPF and, thus, determine the value of the amount of oxygen WRO2_11_Lambda (block S3).

Therefore, if the above conditions are both valid (block S5), the system S is designed to determine the particulate combustion rate in the particulate filter GPF in case of excess oxygen for conducting the particulate combustion reaction GPF_Soot_Burn_Rate_Firing_Lean as disclosed in more detail below. Note that the system S is designed to provide (block S8) a multiplication index (block S5) to be provided to determine the particulate combustion rate in the particulate filter GPF in case of excess oxygen for conducting the particulate combustion reaction GPF_Soot_Burn_Rate_Firing_Lean; in particular, the multiplication index can take binary value, specifically equal to 0 if at least one of the above conditions is determined to be invalid and equal to 1 if both of the above conditions are determined to be valid. In other words, the aforementioned soot combustion rate in the particulate filter GPF in the case of excess oxygen for conducting the soot combustion reaction GPF_Soot_Burn_Rate_Firing_Lean is determined only if both of the above conditions are determined to be valid.

In order to determine the soot combustion rate in the particulate filter GPF in the case of excess oxygen for conducting the soot combustion reaction GPF_Soot_Burn_Rate_Firing_Lean, the system S is designed to:

• determine (block S6) a value related to a degree of soot combustion based on the value of exhaust oxygen concentration mass flow Exh_O2_Mass_Flow and soot load in the particulate filter GPF GPF_Soot_Load;
• determine (block S7) a soot temperature multiplication value based on the temperature of the particulate filter GPF GPF_Temp; and
• if it is verified that the vehicle V is fueled and the concentration of oxygen at the inlet of the particulate filter GPF is greater than the predetermined threshold value WRO2_US_Firing_Thr, determine (block S8) the soot combustion rate in the particulate filter GPF in case of excess oxygen for conducting the soot combustion reaction GPF_Soot_Burn_Rate_Firing_Lean also on the basis of the value related to a soot combustion degree and the soot temperature multiplication value.

In greater detail, according to one aspect of the present invention, in order to determine (block S6) the value relating to a degree of soot combustion, the system S is designed to extract the value relating to a degree of soot combustion from a value map, referred to in the following as Surf_Lean_Mix, dependent on the values of the exhaust oxygen concentration mass flow Exh_O2_Mass_Flow and the soot load in the particulate filter GPF GPF_Soot_Load. In addition, in order to determine (block S7) the soot temperature multiplication value, system S is designed to extract the temperature multiplication value from a temperature multiplication vector, denoted in the following as GPF_Temp_Multiplier_Lean, based on the value of the temperature of the particulate filter GPF GPF_Temp.

Therefore, the soot combustion rate in the particulate filter GPF in case of excess oxygen for conducting the soot combustion reaction GPF_Soot_Burn_Rate_Firing_Lean is the soot combustion rate derived from the value map Surf_Lean_Mix, the latter being a calibratable surface, dependent on the amount of exhaust oxygen Exh_O2_Mass_Flow, the latter being dependent on the amount of oxygen entering the particulate filter GPF and of the soot load in the particulate filter GPF GPF_Soot_Load. Note that the value map Surf_Lean_Mix is populated by running a dyno analysis of the internal combustion engine MT of the vehicle V at different levels of exhaust oxygen amount Exh_O2_Mass_Flow and at different temperatures of the particulate filter GPF and repeating it for various soot load values.

The value thus obtained from the value map Surf_Lean_Mix is then multiplied by the aforementioned multiplication index and soot temperature multiplication value, the latter being an index to dampen the value relative to a degree of soot combustion obtained, i.e., apply a weighting to it. Note that, if the multiplication index is equal to 1, i.e., the above conditions at block S5 are valid, the temperature considered for soot combustion is the maximum acceptable temperature for particulate combustion in the particulate filter GPF; otherwise, if the multiplication index is 0, then the temperature considered for particulate combustion is the minimum acceptable temperature for soot combustion in the particulate filter GPF, i.e., we have a particulate combustion rate in the particulate filter GPF in the case of excess oxygen for conducting the soot combustion reaction GPF_Soot_Burn_Rate_Firing_Lean that is essentially zero.

As also highlighted in Figure 1, the model of soot combustion rate in the particulate filterGPF GPF_Soot_Load_Rate_Mdld is also fitted as a function of a soot combustion rate in the particulate filter GPF in the case of high temperature, denoted in the following as GPF_Soot_Burn_Rate_Firing_High_Temp; in particulate matter, this model relates to the particulate combustion rate at high temperature of the particulate filter GPF, derived, for example, from a Boudouard reaction, where high particulate loads and high internal combustion engine MT speeds occur due to high carbon dioxide fluxes and high exhaust gas temperature.

In particular, with reference to Figure 1, after acquiring the soot combustion rate model in the particulate filter GPF GPF_Soot_Load_Rate_Mdld, the soot load regeneration combustion rate model in the particulate filter GPF GPF_SL_Regen_Burn_Rate_Mdld, the quantities indicative of exhaust oxygen concentration mass flow Exh_O2_Mass_Flow, of the soot load in the particulate filter GPF GPF_Soot_Load and the temperature of the particulate filter GPF GPF_Temp, and in addition to performing the previously described phases to determine the soot combustion rate in the particulate filter GPF in the case of excess oxygen for conducting the soot combustion reaction GPF_Soot_Burn_Rate_Firing_Lean, the system S is also designed to:

• determine the soot combustion rate in the particulate filter GPF in case of high temperature GPF_Soot_Burn_Rate_Firing_High_Temp based on the gas flow Exh_ Mass_Flow, the soot load in the particulate filter GPF GPF_Soot_Load, and the temperature of the particulate filter GPF GPF_Temp; and
• determine the actual soot combustion rate in the particulate filter GPF also based on the soot combustion rate in the particulate filter GPF at high temperature GPF_Soot_Burn_Rate_Firing_High_Temp.

Similar to what is disclosed with reference to Figure 2, in order to determine the soot combustion rate in the particulate filter GPF in the case of high temperature GPF_Soot_Burn_Rate_Firing_High_Temp, the system S is designed to

• verify (blocks S10) that vehicle V is in a phase wherein it is fuelled, i.e., the vehicle V is not in DFSO mode;
• verify (blocks S12) that the temperature of the particulate filter GPF GPF_Temp (acquired by the S system at block S13) is greater than or equal to a predetermined threshold value, shown below as Temp_Burn_Firing_Thr (acquired by the S system at block S14).

In particular, the phases shown with reference to blocks S12 are indicative that the temperature of the particulate filter GPF is suitable for soot combustion in the particulate filter GPF itself.

Therefore, if the above conditions are both valid (block S15), the system S is designed to determine the soot combustion rate in the particulate filter GPF at high temperature GPF_Soot_Burn_Rate_Firing_High_Temp as disclosed in more detail below. Note that, similar to what is disclosed with reference to Figure 2, the system S is designed to provide (block S15) a relative multiplication index to be provided to determine the soot combustion rate in the particulate filter GPF in the case of high temperature GPF_Soot_Burn_Rate_Firing_High_Temp; in particular, the multiplication index can take binary value, specifically equal to 0 if at least one of the above conditions is determined to be invalid and equal to 1 if both of the above conditions are determined to be valid. In other words, the abovementioned soot combustion rate in the particulate filter GPF under high temperature GPF_Soot_Burn_Rate_Firing_High_Temp is determined only if both of the above conditions are determined to be valid.

In order to determine the soot combustion rate in the particulate filter GPF in the case of high temperature GPF_Soot_Burn_Rate_Firing_High_Temp, the S system is designed to:

• determine (block S16) a value related to a degree of soot combustion based on the value of exhaust gas mass flow Exh_Mass_Flow and soot load in the particulate filter GPF GPF_Soot_Load;
• determine (block S17) a soot temperature multiplication value based on the temperature of the particulate filter GPF GPF_Temp; and
• if it is verified that the vehicle V is fuelled and that the temperature of the particulate filter GPF GPF_Temp is greater than or equal to the predetermined threshold value Temp_Burn_Firing_Thr, determine (block S18) the soot combustion rate in the particulate filter GPF in case of high temperature GPF_Soot_Burn_Rate_Firing_High_Temp also on the basis of the value related to a soot combustion degree and soot temperature multiplication value.

In more detail, according to one aspect of the present invention, in order to determine (block S16) the value relative to a degree of soot combustion, the system S is designed to extract the value relative to a degree of soot combustion from a value map, denoted in the following as Surf_High_Temp, dependent on the values of exhaust gas mass flow Exh_Mass_Flow and soot load in the particulate filter GPF GPF_Soot_Load. In addition, in order to determine (block S17) the soot temperature multiplication value, system S is designed to extract the temperature multiplication value from a temperature multiplication vector, denoted below as GPF_Temp_Multiplier_High_Temp, based on the value of the temperature of the particulate filter GPF GPF_Temp.

Therefore, the particulate combustion rate in the GPF particulate filter at high temperature GPF_Soot_Burn_Rate_Firing_High_Temp is the particulate combustion rate derived from the Surf_High_Temp value map, the latter being a calibratable surface, dependent on the exhaust gas mass flow Exh_Mass_Flow, the latter being dependent on the amount of oxygen input to the particulate filter GPF and the soot load in the GPF particulate filter GPF_Soot_Load. Note that the value map Surf_High_Temp is populated by running a dyno analysis of the internal combustion engine MT of the vehicle V at different levels of exhaust gas mass quantity resulting from the exhaust gas mass flow Exh_Mass_Flow and at different temperatures of the particulate filter GPF and repeating it for various particulate load values.

The value thus obtained from the value map Surf_High_Temp is then multiplied by the above multiplication index and the soot temperature multiplication value, the latter being an index for damping the value relative to a degree of soot combustion obtained by applying a weighting to it. Note that, if the multiplication index is equal to 1, i.e., the above conditions at block S18 are valid, the temperature considered for soot combustion is the maximum acceptable temperature for particulate combustion in the particulate filter GPF; otherwise, if the multiplication index is 0, the temperature considered for particulate combustion is the minimum acceptable temperature for soot combustion in the particulate filter GPF, i.e., we have a soot combustion rate in the particulate filter GPF at high temperature GPF_Soot_Burn_Rate_Firing_High_Temp that is essentially zero.

Based on the above disclose, the advantages that the present invention achieves are obvious.

In particular, the present invention makes it possible to improve the accuracy of the model related to the particulate matter accumulated in the particulate filter GPF of the V vehicle, so as to facilitate the fulfilment of the requirements of the emission limits, KPIs or key performance indicators for drivability and durability of the particulate filter GPF itself.

In addition, the present invention also achieves, through increased accuracy, increased robustness in the emission control of the internal combustion engine MT, increased durability and improved driveability.