GB2522808A

GB2522808A - Method of operating an aftertreatment system of an automotive system

Info

Publication number: GB2522808A
Application number: GB1508285.2A
Authority: GB
Inventors: Luca Gatti; Mario Biagioni
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2015-05-14
Filing date: 2015-05-14
Publication date: 2015-08-05
Anticipated expiration: 2035-05-14
Also published as: GB2522808B; GB201508285D0

Abstract

Said aftertreatment system comprise a Diesel Particulate Filter (DPF, 500, figure 3), and the DPF is equipped with a brick (530, figure 3). Said method comprises the steps of: performing a DPF regeneration 700; obtaining pressure values upstream and downstream of the DPF; calculating a difference Î”p of pressure between the pressure values upstreamand downstream of the DPF, 730; reading from a map, a value representative of a backpressure 735 due to the brick of the DPF; calculating a ratio between the pressure difference and the brick backpressure 740, using the calculated ratio to correct the output of the map (535, figure 3). The invention can also comprise an apparatus which has means for performing the steps of the method above. The method allows for an automatic correction of the values of the clean map and can reduce the calibration time needed for calibrating a clean map. The method can also vary the length of the DPF regeneration by a first predetermined percentage before obtaining the pressure values 720. It can also vary the length of the regeneration by a second predetermined percentage before obtaining the pressure values depending on if efficient DPF regeneration conditions are met 725.

Description

METHOD OF OPERATING AN AFTERTREATMENT SYSTEM OF AN AUTOMOTIVE

SYSTEM

TECHNICAL FIELD

The technical field relates to a method of operating an aftertreatnient system of an automotive system.

BACKGROUND

It is known that internal combustion engines, and in particular Diesel engines, are equipped with exhaust gas aftertreatment systems.

Aftertreatment systems treat exhaust gases that exit the combustion chamber and that are directed into an exhaust pipe having one or more aftertreatment devices configured to filter and/or change the composition of the exhaust gases, such as for example an Oxidation Catalyst (DOC), a Diesel Particulate Filter (DPF), a Lean NO Trap (LNT), and/or a Selective Catalytic Reduction (SCR) system or a SCRF (SCR on Filter).

In particular, Diesel Particulate Filters (DPFs) include a substrate used as a particulate filter, generally known as a substrate brick or simply brick.

As is also known in the art, these pariculate filters are used in the aftertreatment systems of internal combustion engines, to trap and remove particulate mailer which is primarily formed of carbon based material. As the engine exhaust passes through the DPF, the particulates are trapped in the brick and accumulate overtime.

In order to guarantee and/or restore the efficiency of the DPF, it may be necessary to remove the particulate matter or soot that progressively accumulates inside the DPF to prevent the pressure drop across the filter from becoming excessive.

This process, which is conventionally known as DPF regeneration, is achieved by increasing the temperature of the exhaust gases entering the DPF (typically up to 630°C), which in their tum heat the filter up to a temperature at which the accumulated particulate burns off.

A known strategy to increase the exhaust gas temperature provides for the exhaust gases to be mixed with a certain amount of unburned fuel (HC) that oxidizes in the oxidation catalyst, thereby heating the exhaust gases that subsequently pass through the DPF. The unburned fuel may come from the engine cylinder thanks to the so called post injections or may be supplied by means of a dedicate fuel injector, which may be located directly in the exhaust pipe, upstream of the DOC.

is A DPF regeneration is initiated when the DPF is deemed full of particulates. The ECU continuously estimates the amount of emitted particulates or soot since the last DPF regeneration based on engine operating parameters.

On current Diesel engines applications the DPF soot loading estimation is mainly based on a physical approach, namely on a physical model that considers the physical state of the DPF and uses the measured pressure drop across the DPF This pressure drop is made up of two contributions: * a pressure drop due to the soot stored inside the DPF, and * a pressure drop due to the presence of the brick, also referred in the following

description as brick backpressure.

The brick backpressure is currently evaluated by specific tests and stored in the ECU by means of a map generally known in the art as clean map.

A variation in the brick backpressure may cause an error on the estimation of the amount of the soot actually present in the DPF, leading to an increase in the regeneration frequency in case of a brick having high backpressure or, on the other hand, to the risk of performing a regeneration too late, namely when a brick is already overloaded in case of a brick having a low backpressure.

Such variations of the performance of the brick occur in practice and are due to several factors, such as the production spread of the components involved in the soot estimation, namely brick porosity, delta pressure sensor dispersion and Mass Flow sensor dispersion, and all these phenomena reduce the accuracy of the physical model.

In particular, a sensible difference may arise between the pressure values read by the sensors and the one estimated by the model in case of an empty DPF.

An object of the invention is to improve the accuracy of the physical model used to estimate the quantity of soot present in the brick of a DPF.

Another object is to reach the above result without using complex devices and by taking advantage from the computational capabilities of the Electronic Control Unit (ECU) of the vehicle.

These and other objects are achieved by a method, by an apparatus, by a computer program and a computer program product, having the features recited in the independent claims.

The dependent claims delineate preferred and/or especially advantageous aspects.

SUMMARY

An embodiment of the disclosure provides a method of operating an aftertreatment system of an automotive system, the aftertreatment system comprising a Diesel Particulate Filter (DPF), the DPF being equipped with a brick, the method comprising the steps of: -performing a DPF regeneration; -obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF; s -calculating a difference of pressure between the pressure values upstream and downstream of the DPF; -reading from a map a value representative of a backpressure due to the brick of the DPF, -calculating a ratio between the pressure difference and the brick backpressure; -using the calculated ratio to correct.the output of the map.

An effect of this embodiment is that it allows to automatically correct the values of the clean map on the basis of the real performance of the specific component, namely the brick of the DPF, installed on the vehicle.

Furthermore, this embodiment guarantees a sensible improvement of the physical model soot estimation accuracy, in particular for borderline components.

Moreover, this embodiment allows to take into account the ashes effect that alters the backpressure values of the aged components.

Finally, this embodiment allows for a reduction in the calibration time needed for calibrating the clean map.

According to another embodiment, the length of the DFF regeneration is increased by a first predetermined percentage thereof before the step of obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPE An effect of this embodiment is that it allows to ensure that the soot quantity stored in the DPF is zero or very close to zero.

According to another embodiment, the length of the DPF regeneration is increased by a second predetermined percentage thereof before the step of obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF, if efficient DPF regeneration conditions are not met.

An effect of this embodiment is that it allows to ensure that the soot quantity stored in the DPF is zero or very close to zero, in case of a non-efficient DPF regeneration.

According to still another embodiment, the efficient DPF regeneration conditions are evaluated by monitoring the DPF regeneration for a predetermined interval of time and are satisfied if: -an average DPF inlet temperature value is comprised between a minimum and maximum value thereof; -a maximum DPF inlet temperature value is lower than a predefined threshold thereof; -a vehicle average speed value is comprised between a minimum and maximum value thereof; -a vehicle maximum speed value is lower than a predefined threshold thereof; and -a residual soot quantity in the DPF is lower than a predefined threshold thereof.

An effect of this embodiment is that it allows to determine if an efficient and complete DPF regeneration has occurred.

According to a further embodiment, after the conclusion of the DPF regeneration, the step of obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF is performed after a predetermined delay.

An effect of this embodiment is that it allows sufficient time for cooling off the DPF.

According to a further embodiment, a scalar factor is set equal to the calculated ratio if the calculated ratio is comprised between a minimum and maximum value thereof and the scalar factor is used to correct the output of the map.

An effect of this embodiment is that it allows to identify components whose performance is within desired limits and also to identify components that do not meet

minimum specifications thereof.

According to still another embodiment, a first DPF regeneration is performed after the vehicle has travelled for a first predetermined distance.

An effect of this embodiment is that it allows to avoid performing DPF regenerations when they are not yet necessary, reducing fuel consumption.

According to another embodiment, a subsequent DPF regeneration is performed after the vehicle has travelled for a second predetermined distance from the last efficient DPF regeneration.

An effect of this embodiment is that it allows to perform DPF regeneration at regular intervals of time with the aim of periodically correct the clean map.

According to another embodiment, the length of a subsequent DPF regeneration is increased by a third predetermined percentage thereof, if no efficient DPF regeneration is is detected for a third predetermined distante travelled by the vehicle after an efficient DPF regeneration.

An effect of this embodiment is that it allows to regenerate the DPF even if no efficient regeneration have been recently performed.

The invention further provides an apparatus for operating an aftertreatment system of an automotive system, the aftertreatment system comprising a Diesel Particulate Filter (DPF), the DPF being equipped with a brick, the apparatus comprising: -means for performing a DPF regeneration; -means for obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF; -means for calculating a difference of pressure between the pressure values upstream and downstream of the DPF; -means for reading from a map a value representative of a backpressure due to the brick of the DPF; -means for calculating a ratio between the pressure difference and the brick backpressure; and -means for using the calculated ratio to correct the output of the map.

The effect of this aspect are similar to those provided by the method, namely to allow to correct automatically the values of the clean map on the basis of the real performance of the specific component, namely the brick of the DPF, installed on the vehicle.

Furthermore, this aspect guarantees a sensible improvement of the physical model soot estimation accuracy, in particular for borderline components.

Moreover, this aspect allows to take into account the ashes effect that alters the backpressure values of the aged components.

Finally, this aspect allows for a redjction in the calibration time needed for calibrating the clean map.

According to another aspect of the invention, the means for obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF are respective pressure sensors.

An effect of this aspect is that it allows to obtain the pressure values by employing sensor equipment already generally present on the vehicle.

According to another aspect of the invention, the apparatus comprises means for increasing the length of the DPF regeneration by a first predetermined percentage thereof before the step of obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF.

An effect of this aspect is that it allows to ensure that the soot quantity stored in the DPF is zero or very close to zero.

According to another aspect1 the apparatus comprises means for increasing the length of the DPF regeneration by a second predetermined percentage thereof before the step of obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF, if efficient DPF regeneration conditions are not met.

An effect of this aspect is that it allows to ensure that the soot quantity stored in the DPF is zero or very close to zero, in case of a non-efficient DPF regeneration.

According to still another aspect, the apparatus comprises means for evaluating efficient DPF regeneration conditions by monitoring the DPF regeneration for a predetermined interval of time and means to determine that such conditions are satisfied if: -an average DPF inlet temperature value is comprised between a minimum and maximum value thereof; -a maximum DPF inlet temperature value is lower than a predefined threshold thereof; -a vehicle average speed value is comprised between a minimum and maximum value thereof; -a vehicle maximum speed value is lower than a predefined threshold thereof; and -a residual soot quantity in the DPF is lower than a predefined threshold thereof.

An effect of this aspect, is that it allows to determine if an efficient and complete DPF regeneration has occurred.

According to a further aspect, the apparatus comprises means for performing, after a predetermined delay after the conclusion of the DPF regeneration, the step of obtaining a pressure value upstream of the DPF and a pressure value downstream of the DPF.

An effect of this aspect is that it allows sufficient time for cooling off the DPF.

According to a further aspect, the apparatus comprises means for setting a scaler factor equal to the calculated ratio, if the calculated ratio is comprised between a minimum and maximum value thereof and to use the scaler factor to correct the output of the map.

An effect of this aspect is that it allows to identify components whose performance is within desired limits and also to identify components that do not meet minimum

specifications thereof.

According to still another aspect, the apparatus comprises means for performing a first DPF regeneration after the vehicle has travelled for a first predetermined distance.

An effect of this aspect is that it allows to avoid performing DPF regenerations when they are not yet necessary, reducing fuel consumption.

According to another aspect, the apparatus comprises means for performing a subsequent DPF regeneration after the vehicle has travelled for a second predetermined distance from the last efficient DPF regeneration.

An effect of this aspect, is that it allows to perform DPF regeneration at regular intervals of time with the aim of periodically correct the clean map.

According to another aspect, the apparatus comprises means for increasing the length of a subsequent DPF regeneration by a third predetermined percentage thereof, if no efficient DPF regeneration is detected for a third predetermined distance travelled by the vehicle after an efficient DPF regeneraticn.

An effect of this aspect is that it allows to regenerate the DPF even if no efficient regeneration have been recently performed.

The method according to one of its aspects can be carried out with the help of a computer program comprising a program-code for carrying out all the steps of the method described above, and in the form of computer program product comprising the computer program.

The computer program product can be embodied as a control apparatus for an internal combustion engine, comprising an Electronic Control Unit (ECU), a data carrier s associated to the ECU, and the computer program stored in a data carrier, so that the control apparatus defines the embodiments described in the same way as the method. In this case, when the control apparatus executes the computer program all the steps of the method described above are carried out.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, wherein like numerals denote like elements, and in which: Figure 1 shows an automotive system; Figure 2 is a cross-section of an internal combustion engine belonging to the automotive system of figure 1; Figure 3 shows some details of the automotive system of Figure 1; Figure 4 is a graph representing a distribution of pressure due to the soot accumulated in a DPF versus the pressure to the brick of a DPF for a reference case; Figure 5 is a graph representing a distribution of pressure due to the soot accumulated in a DPF versus the pressure to the brick of a DPF, in case of a brick that exhibits a high backpressure; Figure 6 is a graph representing a distribution of pressure due to the soot accumulated in a DPF versus the pressure to the brick of a DPF, in case of a brick that exhibits a low backpressure; and Figure 7 is a flowchart representing an embodiment of the invention.

DETAILED DESCRIPTION

Exemplary embodiments will now be described with reference to the enclosed drawings without intent to limit application and uses.

Some embodiments may include an automotive system 1001 as shown in Figures 1 and 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145.

A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150.

A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received from a fuel source 190. Each of the cylinders has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an aftertreatment system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The aftertreatment system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition ot the exhaust gases. Some examples of aftertreatment devices 260 include1 but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NO:( traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters, such as a Diesel Particulate Filter (DPF) 500.

The DPF 500 may be associated with a pressure sensor upstream of the DPF 550 and pressure sensor downstream of the DPF 560, both sensors being used in combination to measure a difference of pressure Ap between an outlet and an inlet of the DPF 500.

Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110.

The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 446. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with a memory system, or data carrier 460, and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the CPU to carry out the steps of such methods and control the ICE 110.

The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 100 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.

An example of a transitory computer program product is a signal, e.g. an S electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulation technique such as QPSK for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a Wi-Fi connection to a laptop.

In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a retrievable way in or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.

Instead of an ECU 450, the automotive system 100 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the vehicle.

Figure 3 shows some details of the automotive system 100 of Figure 1, wherein in the exhaust pipe 275, the DPF 500, equipped with a brick 530, is provided.

As is known in the art, a brick 530 of a DPF is a substrate used as a particulate filter suitable for trapping a certain quantity of soot therein.

The DPF 500 is associated with a pressure sensor upstream of the DPF 550 and pressure sensor downstream of the DPF 560, both sensors being used in combination to measure a difference of pressure Lip between an outlet and an inlet of the DPF 500.

In Figure 3, a so-called clean map 535 is also schematically represented, the map 535 correlating the pressure drop due to the presence of the brick 530 in the DPF 500, also referred as brick backpressure, with a specific brick 530 mounted insed the DPF 500 of the vehicle 105.

The map 535 is evaluated by means of an experimental activity and stored in the data carrier 460 associated with the ECU 450, Finally, a DPF inlet temperature sensor 570 is also represented.

Figure 4 is a graph representing a distribution of pressure due to the soot accumulated in a DPF versus the pressure due to the brick 530 of a DPF 500 for a reference case.

In this case, the whole cylinder 600 represents an exemplary value of a measured difference of pressure Lip between an outlet and an inlet of the DPF 500 for a standard brick 530.

In this exemplary case, the backpressure 610 due to the brick 530 is substantially equal to the backpressure 620 due to the soot in the DPF 500.

Figure 5 is a graph representing a distribution of pressure due to the soot accumulated in a DPF versus the pressure to the brick 530 of a DPF 500 in case of a brick that exhibits a high backpressure 650.

In this case, even if the measured difference of pressure Lip between an outlet and an inlet of the DPF 500, represented by cylinder 600, is the same of the one represented in Figure 4, the backpressure 650 due to the brick 530 is substantially higher than the backpressure 640 due to the soot in the DPF 500.

Since the measured difference of pressure Lip between an outlet and an inlet of the DPF 500 is the same for the cases of Figure 4 and 5, the physical model will evaluate the same quantity of soot.

However, in the case of the component of Figure 5 with high brick backpressure, the actual quantity of soot is substantially lower than the one estimated by the physical model, therefore an unnecessary high frequency of regenerations may occur.

Figure 6 is a graph representing a distribution of pressure due to the soot accumulated in a DPF versus the pressure to the brick 530 of a DFF 500 in case of a brick that exhibits a low backpressure 680.

In this case, even if the measured difference of pressure Ap between an outlet and an inlet of the DPF 500,represented by cylinder 660, is the same of the one represented in Figure 4, the backpressure 680 due to the brick 530 is substantially higher than the backpressure 630 due to the soot in the DPF 500.

Since the measured difference of pressure âp between an outlet and an inlet of the DPF 500 is the same for the cases of Figure 4 and 6, the physical model will evaluate the same quantity of soot.

However, in the case of the component of Figure 6 with low brick backpressure, the actual quantity of soot is substantially lower than the one estimated by the physical model, therefore the regenerations may occur only when the brick is overloaded with soot.

The various embodiments of the method are now described with particular reference to the flowchart of Figure 7.

The aim of the method is to correct the map 535 using a multiplicative parameter K which is initialized at the value of 1.

At the start of the method, a DPF regeneration is performed (block 700).

A check is then performed to verify if the DPF regeneration has been efficient and complete (block 700).

Efficient DPF regeneration conditions are evaluated by monitoring the DPF regeneration for a predetermined interval of time t2 and are satisfied if an average DPF inlet temperature value T_DPF is comprised between a minimum and maximum value the reot Moreover, another efficient DPF regeneration condition is that a maximum DPF inlet temperature value r_DPFU,, is lower than a predefined threshold thereof.

The DPF inlet temperature value T_DPF may be measured by DPF inlet temperature sensor 570.

Other efficient DPF regeneration conditions to be evaluated are that the vehicle 105 average speed value Vspeed is comprised between a minimum and maximum value thereof and the vehicle 105 maximum speed value Vspeed is lower than a predefined threshold thereof.

Finally, another efficient DPF regeneration condition is that a residual soot quantity SootQ in the DPF 500 is lower than a predefined threshold thereof.

If the DPF regeneration is considered efficient, then the length of the DPF regeneration is increased by a first predetermined percentage thereof X1% before the step of obtaining a pressure value upstream P_DPFUP of the OPF 500 and a pressure value downstream P_OPFd.,,, of the DPF 500 (block 720).

An exemplary value of the predetermined percentage of increase X1% of the DPF regeneration can be 20%, leading to total OFF regeneration time of 120% of a standard DPF regeneration.

On the contrary, if efficient DPF regeneration conditions are not met the length of the DPF regeneration is increased by a second predetermined percentage thereof X2% before the step of obtaining a pressure value upstream P_DPFUP of the OFF 500 and a pressure value downstream P_DPFdOM, of the DPF 500 (block 715).

An exemplary value of the predetermined percentage of increase)C'l% of the DPF regeneration can be 60%, leading to total DPF regeneration time of 160% of a standard DPF regeneration.

S Normally, the step of obtaining a pressure value upstream P_DPFUP of the DPF 500 and a pressure value downstream P_DPFdOWI, of the DPF 500 is not performed immediately, but after a predetermined delay ti (block 725).

This delay ft is calculated in order to allow sufficient time for the DPF 500 to cool down.

A possible exemplary value for the time delay tl is 200 seconds.

After the time delay ti, the pressure value upstream P_DPFW,, of the OPF 500 and the pressure value downstream P_DPFdOV.V of the DPF 500 are obtained, for example by means of measurements by the respective pressure sensors 550, 560.

Then a difference of pressure Lip between the pressure values upstream and downstream P_DPFUP JP_DPFJOVTh of the DPF 500 is calculated (block 730).

In parallel, a value representative of a backpressure Pb,ftk due to the brick 530 of the DPF 500 is read from map 535 (block 735).

Once difference of pressure value Ap and the brick backpressure value Po,k have been obtained, a ratio K8 between the pressure difference Lip and the brick backpressure Podck is calculated (block 740).

A check is then performed to verify that the calculated ratio K, is comprised between a minimum and maximum value thereof (block 745), in other words a saturation procedure is performed on the value K8 to verify that this value is comprised between

acceptable limits.

If this is not the case, the particular brick 535 of the DPF 500 may be considered outside acceptable limits for use in the vehicle 105 On the contrary, if the calculated ratio J( is comprised between a minimum and maximum value thereof, a scalar factor K is set equal to the calculated ratio Kayg (block 750) and the scalar factor K' is used to correct the output of the map 535 (block 755).

In other words the multiplicative parameter K of the clean mao 535 is set equal to K'.

In this way, the clean map 535 is automatically corrected the basis of the real performance of the specific component, namely the brick of the DPF, installed on the vehicle 105.

In general, according to an embodiment of the invention, a first DPF regeneration is performed after the vehicle 105 has travelled for a first predetermined distance Dl, for example for 15.000km.

Any subsequent DPF regeneration may be performed after the vehicle 105 has travelled for a second predetermined distance D2 from the last efficient DPF regeneration detected.

As a precautionary measure in order to have a complete DPF regeneration in any case, the length of a subsequent DPF regeneration is increased by a third predetermined percentage thereof X3%, if no efficient DPF regeneration is detected for a third predetermined distance D3 travelled by the vehicle 105 after an efficient DPF regeneration.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, a being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS

100 automotive system internal combustion engine (ICE) engine block cylinder cylinder head 135 camshaft piston crankshaft combustion chamber cam phaser 160 fuel injector fuel rail fuel pump fuel source intake manifold 205 air intake duct 210 intake air port 215 valves of the cylinder 220 exhaust gas port 225 exhaust manifold 230 turbocharger 240 compressor 250 turbine 260 intercooler 270 aftertreatment system 275 exhaust pipe 280 exhaust aftertreatment device 290 VGT actuator 300 EGR system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant and oil temperature and level sensors 400 fuel rail pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensor 445 accelerator pedal position sensor 450 electronic control unit (ECU) 460 data carrier 500 DPF 530 brick of DPF 535 clean map 550 pressure sensor upstream of the DPF 560 pressure sensor downstream of the DPF 700 block 705 block 710 block 715 block 720 block 725 block 730 block 735 block 740 block 745 block 750 block 755 block

Claims

CLAIMS1. A method of operating an aftertreatment system (270) of an automotive system (100), the aftertreatment system (270) comprising a Diesel Particulate Filter (DPF) (500), the DPF (500) being equipped with a brick (530), the method comprising the steps of: -performing a DPF regeneration; -obtaining a pressure value upstream (P_DPF) of the DPF (500) and a pressure value downstream (P_DPF9,,) of the DPF (500); -calculating a difference of pressure (Ap) between the pressure values upstream and downstream (P_DPFUP,P_DPFØOW,,) of the DPF (500); -reading from a map (535) a value representative of a backpressure (Pb) due to the brick (530) of the DPF (500); -calculating a ratio (K9) between the pressure difference (Lp) and the brick backpressure (Pb,ftk); -using the calculated ratio (K0) to correct the output of the map (535).
2. The method according to claim 1, wherein the length of the DPF regeneration is increased by a first predetermined percentage thereof (X1%) before the step of obtaining a pressure value upstream (P_DPFUP) of the DPF (500) and a pressure value downstream (P_DPFd.,,) of the DPF (500).
3. The method according to claim 1, wherein the length of the DPF regeneration is increased by a second predetermined percentage thereof (X2%) before the step of obtaining a pressure value upstream (P_DPF4 of the DPF (500) and a pressure value downstream (P_DPFd0W,) of the DPF (500), if efficient DPF regeneration conditions are not met.
4. The method according to claim 3, wherein the efficient DPF regeneration conditions are evaluated by monitoring the DPF regeneration for a predetermined interval of time (t2) and are satisfied if: -an average DPF inlet temperature value (T_DPF) is comprised between a minimum and maximum value thereof; -a maximum DPE inlet temperature value (T_DPFUP) is lower than a predefuned threshold thereof; -a vehicle (105) average speed value (Vspeed) is comprised between a minimum and maximum value thereof; -a vehicle (105) maximum speed value (Vspeed) is lower than a predefined threshold thereof; and -a residual soot quantity (SootQ) in The DPF (500) is lower than a predefuned threshold thereot
5. The method according to claim 1, wherein after the conclusion of the DPF regeneration, the step of obtaining a pressure value upstream (P_DPF) of the DPF (500) and a pressure value downstream (P_DPF,,) of the DPF (500) is performed after a predetermined delay (ti).
6. The method according to claim 1, wherein a scalar factor (K) is set equal to the calculated ratio (K,) if the calculated ratio (I4) is comprised between a minimum and maximum value thereof and the scalar factor (K) is used to correct the output of the map (535).
7. The method according to claim 1, wherein a first DPF regeneration is performed after the vehicle (105) has travelled for a first predetermined distance (Dl).
8. The method according to claim 7, wherein a subsequent DPF regeneration is performed after the vehicle (105) has travelled for a second predetermined distance (D2) from the last efficient DPF regeneration.
9. The method according to claim 7, wherein the length of a subsequent DPF regeneration is increased by a third predetermined percentage thereof (X3%), if no efficient DPF regeneration is detected for a third predetermined distance (03) travelled by the vehicle (105) after an efficient DPF regeneration.
10. An apparatus for operating an aftertreatment system (270) of an automotive system (100), the aftertreatment system (270) comprising a Diesel Particulate Filter (DPF) (500), the DPF (500) being equipped with a brick (530), the apparatus comprising: -means for performing a DPF regeneration; -means for obtaining a pressure value upstream (P_DPF) of the DPF (500) and a pressure value downstream (P_0PFdQ,,) of the DPF (500); -means for calculating a difference of pressure (Sp) between the pressure values upstream and downstream (P_DPF; P_DPFdOWn) of the DPF (500); -means for reading from a map (535) a value representative of a backpressure (Pb,1) due to the brick (530) of the DPF (500); -means for calculating a ratio (Kayo) between the pressure difference (Ap) and the brick backpressure (Pb,ftk); -means for using the calculated ratio (Kayg) to correct the output of the map (535).
11. The apparatus according to claim 10, wherein the means for obtaining a pressure value upstream (P_DPFU) of the DPF (500) and a pressure value downstream (P_DPF4 of the DPF (500) are respective pressure sensors (550, 560).
12. An automotive system (100) comprising an Electronic Control Unit (450) configured for carrying out the method according to any of the claims 1-9.
13. A computer program comprising a computer-code suitable for performing the method according to any of the claims 1-9.
14. A computer program product on which the computer program according to claim 12 is stored.S
15. A control apparatus for an internal combustion engine (110), comprising an Electronic Control Unit (450), a data carrier (460) associated to the Electronic Control Unit (450) and a computer program according to claim 12 stored in the data carrier (460).