EP4023866A1

EP4023866A1 - Diesel particulate filter diagnostic

Info

Publication number: EP4023866A1
Application number: EP21215173.2A
Authority: EP
Inventors: David Deregnaucourt
Original assignee: ECOSPHERE SA; ECOSPHERE S A
Current assignee: ECOSPHERE SA; ECOSPHERE S A
Priority date: 2020-12-31
Filing date: 2021-12-16
Publication date: 2022-07-06
Also published as: LU102367B1

Abstract

Aspects of the present inventions relate to a diesel particulate filter (DPF) diagnostic method, a computer program comprising instructions to carry out the method and a computer program product comprising a computer readable medium having stored thereon the computer program. The method comprises receiving, by a server, DPF data comprising a pressure drop across the DPF. The method also comprises determining, by the server, a DPF soot load by processing the pressure drop, and transmitting, by the server, the determined DPF soot load to a client terminal. Further DPF data comprising a gas mass flow is received by the server, the pressure drop being obtained at the gas mass flow. The DPF soot load is determined by processing both the pressure drop and the gas mass flow. The gas mass flow is a gas mass flow at the inlet of the DPF or an engine intake gas mass flow.

Description

Field of the Invention

The invention generally relates to a diesel particulate filter (DPF) diagnostic method, a computer program comprising instructions for carrying out the DPF diagnostic method and a computer program product comprising a computer readable medium having stored thereon the computer program.

Background of the Invention

Diesel particulate filters (DPFs) mitigate pollution generated by diesel engines. It is usually placed on the engine exhaust of a vehicle in order to filter the particles emitted by combustion engine, which are harmful to humans and the environment.
The DPF comprises a filter element which is made of multiple channels and has limited storage capacity. The more "loaded" the filter, the greater is the resistance to flow (pressure drop) of the exhaust gases. The increase in the pressure drop usually leads to loss of engine efficiency, overconsumption and, in the most extreme cases (e.g. in case of DPF clogging), engine malfunction or failure.
In order to prevent a malfunction, the filter element must be cleaned regularly by performing a so-called regeneration. The regeneration is a chemical oxidation reaction that takes place between 550°C and 650°C. The particles (i.e. carbon aggregates) are transformed into CO₂.
The regeneration can be triggered for instance if the driving conditions allow adequate temperature (550°C and 650°C) to be generated. Alternatively or additionally, if the driving conditions are inadequate, a control unit may warn the user that a motorway trip (e.g. via a DPF warning light) is mandatory for regenerating the filter element. In some cases, the regenerations fail or are partially carried out which greatly impairs the performance of the vehicle. In case of high loading of the DPF, the regeneration conditions may never be attained, thereby preventing a regeneration of the DPF and most certainly leading to engine malfunction or failure.
The diagnostic of the load of a DPF is usually carried out in a car or truck workshop, where the workshop personnel measures the pressure drop across the DPF and assess whether the pressure drop is higher or lower than a home-defined, subjective, threshold. It defines whether or not the DPF needs to be replaced or manually cleaned. Replacing or manually cleaning the DPF is very expensive.

General Description

As a consequence, an accurate determination of the load of the DPF is needed in order to avoid unnecessary costs for the customer and provide adequate DPF servicing measures. For instance, the regeneration of the DPF can be improved by adding an additive for reducing the oxidation temperature, in case of low DPF loads. The diesel engine injectors can also be cleaned so as to improve the post-injections of fuel (post-injections are used to increase temperature). In case of a high DPF load, it may not be possible to obtain a temperature that allows for regenerating the DPF. In that case, a replacement or manual cleaning of the DPF is necessary. Of course, an inaccurate determination of the DPF load will lead to either unnecessary expensive DPF servicing measures when not necessary or lack thereof when necessary.
A reliable, trustworthy, standardized and improved diagnostic method of the DPF would thus be appreciated by workshops so that they may correctly assess the load of the DPF as well as implement adequate DPF servicing measures, if needed, and also appreciated by customers. One of the goals of the present invention is to provide such a DPF diagnostic method.
A first aspect of the invention relates to a DPF diagnostic method, comprising:

∘ receiving, by a server, DPF data comprising a pressure drop across the DPF;
∘ determining, by the server, a DPF soot load by processing the pressure drop; and
∘ transmitting, by the server, the determined DPF soot load to a client terminal; wherein further DPF data comprising a gas mass flow is received by the server, the pressure drop being obtained at the gas mass flow, the DPF soot load being determined by processing both the pressure drop and the gas mass flow. The gas mass flow is a gas mass flow at the inlet of the DPF or an engine intake gas mass flow.

It will first be appreciated that the first aspect of the present invention separates the client side (e.g. workshops) from the server side. The server side is fed by the client side with DPF data comprising the gas mass flow and the pressure drop and provides, in return, the client side with a DPF soot load. This allows for taking away the task of determining the DPF soot load from the client side. In addition, this also allows for providing a standardized diagnostic method, in the sense that the processing of received DPF data is the same irrespective of the workshop providing DPF data. It will also be appreciated that the first aspect of the present allows for providing a diagnostic method that is reliable and trustworthy since diagnostic tampering risks are mitigated. Indeed, the workshops have not access to the server-side processing of the DPF data.
It will further be appreciated that the DPF soot load is determined by processing both the pressure drop and the gas mass flow. The inventors have found that the pressure drop increases or decreases in case the gas mass flow increases or decreases, respectively. The first aspect of the present invention thus takes into account the gas mass flow in the determination of the DPF soot load, thereby providing a more accurate DPF soot load.
It should be noted that the gas mass flow at the inlet of the DPF is (slightly) greater than the engine intake gas mass flow. The difference originates from the additional gas generated by the vaporization of the fuel injected in the engine. The difference between the two gas mass flows is usually not greater than 1/50 of the intake gas mass flow at constant revolutions per minute (rpm), so that a correction factor may be applied for converting the gas mass flow at the inlet of the DPF to the intake gas mass flow (factor: 0.98) or vice-versa (factor: 1.02).
According to an embodiment, the server has electronic access to a map mapping a pressure drop and a gas mass flow to a DPF soot load. The server preferably determines the DPF soot load by using the map for processing the pressure drop and gas mass flow. As will be appreciated, the map takes as inputs the pressure drop and to gas mass flow and maps the inputs onto a DPF soot load.
The map may be stored in any suitable electronic form, e.g. as a function with (or without) adjustable parameters (which may be adjusted by optimizing an objective function, e.g. by minimizing a cost or loss function or maximizing a reward or profit function) or as one or more lookup tables, in a local memory of the server or in a storage place that the server is connected to by a data connection. The map may be stored in a database.
According to a preferred embodiment, DPF soot loads with respect to pressure drops and to gas mass flows may be stored in a look-up table. The processing of both the pressure drop and the gas mass flow may comprise querying the look-up table for a DPF soot load at the pressure drop and the gas mass flow (i.e. providing the pressure drop and the gas mass flow as inputs). The lookup-table thus stores DPF soot loads for different discrete pressure drops and to gas mass flows. In a preferred embodiment, the querying the look-up table may comprise interpolating the DPF soot load at both the pressure drop and the gas mass flow (provided as inputs).
In an embodiment, the received DPF data comprises at least two sets of pressure drops and gas mass flows, each of the at least two set being for different gas mass flows. The DPF soot load is preferably determined by processing the at least two sets of pressure drop and gas mass flow. For example, a DPF soot load may be computed (e.g. using the map -possibly the lookup table) for each of the at least two sets. The DPF soot load to be transmitted to the client terminal may be determined by averaging the computed DPF soot loads. In a preferred embodiment, the received DPF data comprise three sets of pressure drops and gas mass flows. The three sets of pressure drops and gas mass flows may be processed in the same way as described for two sets.
In a preferred embodiment, the determination of the DPF soot load comprises assigning a higher weight to one or more sets of the at least two sets having a higher gas mass flow.
In an embodiment, the DPF diagnostic method may comprise determining DPF data, including:

∘ measuring a gas mass flow; and
∘ measuring a pressure drop across the DPF at the gas mass flow;

The DPF diagnostic method may further comprise transmitting, to the server, a DPF mileage the transmission being effected by the client terminal, and receiving, by the client terminal, a DPF ash load from the server.
According to an embodiment, the DPF measurement protocol comprises prescriptions so as to determine the pressure drop at a predetermined gas mass flow The prescriptions comprise setting one or more operational parameters of an engine to which the DPF is in fluid communication with. The engine has an engine displacement. The one or more operational parameters comprise a predetermined engine revolutions per minute (rpm) with respect to the engine displacement so as to provide the predetermined gas mass flow. In an embodiment. The DPF measurement protocol may comprise prescriptions so as to determine pressure drops for at least two predetermined gas mass flows. In other words, the prescriptions may comprise instructions for providing at least two sets of pressure drops and gas mass flows, each of the at least two set being for different gas mass flows.
The DPF measurement protocol may prescribe a predetermined exhaust gas temperature for measuring the gas mass flow and the pressure drop, preferably the predetermined exhaust gas temperature is comprised in the interval from 200°C to 250°C, more preferably the predetermined exhaust gas temperature is comprised in the interval from 220°C to 230°C.
The determination of the DPF soot load may further based on at least one of a DPF geometry (e.g. channel diameter, channel length, number of channels per square inch), an indicator of whether the DPF comprises a soot oxidation catalyst coating and an indicator of whether a selective catalytic reduction (SCR) catalyst coating (made of e.g. oxides of base metals (such as vanadium, molybdenum and tungsten), zeolites, and/or precious metals) and reducing agent (e.g aqueous ammonia or urea solution such as AdBlue^®) are used. As used herein, an indicator may be implemented as a boolean or any other adequate means.
In a preferred embodiment, the server comprises, or is in communication with, a database including automotive vehicle characteristics of automotive vehicles. The automotive vehicle characteristics are selected from the group consisting of a vehicle registration number, a date of entry into service, vehicle brand, vehicle model, compliance to a European emission standard, an engine model, an engine displacement, an engine power, an indicator of whether the engine is flanged. The method may further comprise receiving, by the server, one or more of the automotive vehicle characteristics. The determination of the DPF soot load maybe carried out on the basis of the received one or more of the automotive vehicle characteristics.
In an embodiment, a part of the vehicle characteristics may be determined from other vehicle characteristics. In that case, this part may not be transmitted by the client terminal. The server may determine the part of vehicle characteristics that may be determined from other, transmitted, vehicle characteristics. For example, the indicator of whether the engine is flanged, or whether the DPF comprises a soot oxidation catalyst coating, may be determined by the server on the basis of at least one of the vehicle registration number, the date of entry into service, vehicle brand, vehicle model, the compliance to a European emission standard, the engine model, the engine displacement and the engine power.
The DPF data may further comprises a mileage of the DPF. The automotive vehicle characteristics may comprise an indicator of whether the automotive vehicles comprise an integrated system for automatic dispensing of a ceria-based fuel-borne catalyst (e.g. Eolys^™ integrated system). The method further comprises determining, by the server, a DPF ash load, the DPF ash load being determined on the basis of the mileage of the DPF. The determination of the DPF ash load is adjusted for taking into account the presence of the integrated system in case the indicator indicates that the integrated system is present. The method further comprises transmitting, by the server, the determined DPF ash load to the client terminal.
The DPF diagnostic method may comprise selecting a map mapping a pressure drop and a gas mass flow to a DPF soot load. The map is preferably stored in the database. The selection is based on the received one or more of the automotive vehicle characteristics. The selected map is preferably calibrated for the received one or more of the automotive vehicle characteristics (and, in fine, to the specific DPF to be diagnosed). The DPF soot load is determined on the basis of the selected map. According to an embodiment, a look-up table may be used. The look-up table is preferably stored in the database.
A DPF measurement protocol may be selected based one the received one or more of the automotive vehicle characteristics. The DPF measurement protocol is preferably stored in the database. The method may further comprise transmitting the selected DPF measurement protocol to the client terminal. The DPF measurement protocol is preferably calibrated for the received one or more of the automotive vehicle characteristics.
The method may further comprise:

∘ collecting at least one of the automotive vehicle characteristics;
∘ transmitting the collected to automotive vehicle characteristics the server, the transmission being effected by the client terminal; and
∘ receiving a DPF measurement protocol from the server.

A second aspect of the present invention is directed to a DPF method including only the step recited for the first aspect that are performed on the client (terminal) side.
Namely, the second aspect of the present invention relates to a DPF diagnostic method comprising determining DPF data, including:

∘ measuring a gas mass flow, wherein the gas mass flow is a gas mass flow at the inlet of the DPF or an engine intake gas mass flow; and
∘ measuring a pressure drop across the DPF at the gas mass flow;

Embodiments of the second aspect of the invention are provided herebelow.
The DPF diagnostic method may comprise:

∘ transmitting, to the server, a DPF mileage, the transmission being effected by the client terminal; and
∘ receiving, by the client terminal, a DPF ash load from the server.

The DPF measurement protocol comprises prescriptions so as to determine the pressure drop at a predetermined gas mass flow, the prescriptions setting one or more operational parameters of an engine to which the DPF is in fluid communication with, the engine having an engine displacement, the one or more operational parameters comprising a predetermined engine revolutions per minute (rpm) with respect to the engine displacement so as to provide the predetermined gas mass flow. In an embodiment, the DPF measurement protocol may comprise prescriptions so as to determine pressure drops for at least two predetermined gas mass flows. The prescriptions may thereby comprise instructions for providing at least two (preferably three) sets of pressure drops and gas mass flows, each of the at least two (preferably three) set being for different gas mass flows.
The DPF measurement protocol may prescribe a predetermined exhaust gas temperature for measuring the gas mass flow and the pressure drop, preferably the predetermined exhaust gas temperature is comprised in the interval from 200°C to 250°C, more preferably the predetermined exhaust gas temperature is comprised in the interval from 220°C to 230°C.
The DPF diagnostic method may comprise:

∘ collecting at least one of the automotive vehicle characteristics;
∘ transmitting the collected to automotive vehicle characteristics the server, the transmission being effected by the client terminal; and
∘ receiving the DPF measurement protocol from the server.

A third aspect of the present invention relates to a computer program comprising instructions, which, when executed by a computer, cause the computer to carry out the method according to the first aspect of the present invention.
A fourth aspect of the present invention relates to a computer program product comprising a computer readable medium having stored thereon a computer program according to the third aspect of the present invention.

Brief Description of the Drawings

By way of example, preferred, non-limiting embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. 1 : is a schematic illustration of a server side of a DPF diagnostic method according to a preferred embodiment of the present invention;
Fig. 2 : is a schematic illustration of a client side of a DPF diagnostic method according to a preferred embodiment of the present invention;
Fig. 3 : is a detailed schematic illustration of a determination of a DPF soot load and DPF ash load according to a preferred embodiment of the present invention; and
Fig. 4 : shows a dependence of the pressure drop as a function of the gas mass flow for a broken DPF as well as DPFs having different soot loads.

Detailed Description of Preferred Embodiments of the Invention

Figs. 1 and 2 illustrate a DPF diagnostic method according to a preferred embodiment of the present invention. Fig. 1 relates more particularly to the operations performed on the server side, and Fig. 2 relates more particularly to the operations performed on the client side. While the DPF diagnostic method is described herebelow as a whole (i.e. comprising the server -see Fig. 1- and the client steps -see Fig. 2) for the sake of conciseness and clarity, the person skilled in the would directly and unambiguously understand that the DPF diagnostic method may be separated in two distinct DPF diagnostic methods, one being directed to the steps performed by the server side, the other one being directed to the steps performed by the client (terminal) side.
The DPF diagnostic comprises collecting 10 (automotive) vehicle characteristics of the vehicle for which the DPF is to be diagnosed. The collection may be carried out by workshop personnel, automatically by diagnostic boxes connected to the vehicle or by a combination thereof. The vehicle characteristics comprises one or more vehicle registration numbers, an engine displacement, an indication of whether the engine is flanged, vehicle date of entry into service, vehicle brand, vehicle model, compliance to a European emission standard, engine power. The collected vehicle characteristics are then transmitted 12 by the client terminal to the server.
The communication between the client terminal and the server may be effected by any adequate means. In an embodiment, the transmission may be effected through a wired or wireless communication network to which the server and the client terminal are part of. The communication may be encrypted or unencrypted. In an embodiment, the server and/or the client terminal need to authenticate themselves before, while and/or after communicating. In an embodiment, the client terminal may be required by the server (or vice-versa) to provide a proof that its systems have not been tampered with. The server and/or the client terminal may be configured to delete their sensitive data -for example the cryptographic keys- if penetration of the security encapsulation of the system and/or out-of-specification parameters are detected. Without cryptographic keys, successful authentication is prevented. In an embodiment, either the server or the client terminal may refuse to receive data from and/or transmit data to the other in case of unsuccessful authentication. In other words, the server and/or the client terminal may only communicate in case of accepted, valid, authentication by the client terminal and/or the server, respectively. Otherwise, the DPF diagnostic method may be aborted (e.g. by the server and/or the client terminal). The authentication may be effected every time a communication channel is established between the client and the server. Alternatively, the authentication may be effected only once during the DPF diagnostic method and e.g. remain valid during the DPF diagnostic method.
As a further check and tamper protection, the server and/or the client terminal may check the collected vehicle characteristics. For example, if the collected vehicle characteristics are outside respective predetermined tolerances, the collected data may be rejected. A warning may be displayed inviting workshop personnel to correct one or more of the collected vehicle characteristics that are outside of the respective predetermined tolerances. For example, a collected engine power of 5000 kW could be rejected.
The transmitted vehicle characteristics 12 are then received 14 by the server. Based on the received vehicle characteristics 12, the server selects 16 a DPF measurement protocol. In an embodiment, the server may provide (at least part of) the transmitted vehicle characteristics 12 to a database (as depicted in Fig. 1), which, in response, provides a DPF measurement protocol. The database may be hosted on a remote machine or directly hosted in the server.
The database is populated with vehicle characteristics in such a way that the database provides a correspondence between the vehicle characteristics and a particular, predetermined, DPF measurement protocol. In other words, the database maps provided vehicle characteristics to a particular DPF measurement protocol. In order words, the selected DPF measurement protocol is specifically designed for the provided vehicle characteristics. In case the database is provided with an unknown combination of vehicle characteristics (e.g. an unknown vehicle), a DPF measurement protocol for which the vehicles characteristics are the closest is selected. A warning message may be transmitted to the client terminal indicating that the combination of vehicle characteristics is unknown. For determining the closest known vehicle, the server may search for a vehicle from the same brand, having same or close engine displacement (e.g. +/-0.5 L) and the same or close production year (e.g. +/- 1 year).
The server may be equipped with an artificial intelligence (AI) module configured to store a history of provided vehicle characteristics. The processing comprises detecting emerging patterns of unknown combinations of vehicle characteristics in the history of provided vehicle characteristics. The AI module may also be configured to validate a combination of vehicle characteristic so that the combination is marked as known and populate the database with an associated DPF measurement protocol. The DPF measurement protocol may be identical to a DPF measurement protocol of a similar vehicle. Alternatively, the DPF measurement protocol may be different. In an embodiment, the AI module may provide its output for external review.
The DPF measurement protocol comprises prescriptions for a preparation step for setting the engine in a specific, controlled, state. This allows for controlling e.g. the exhaust gas temperature. The exhaust gas temperature may be prescribed to a temperature that is comprised in the interval from 200°C to 250°C, more preferably in the interval from 220°C to 230°C. For achieving this, the DPF measurement protocol may, for example, require a pre-heating phase of the engine. For example, DPF measurement protocol may require setting the engine to 4000 revolutions per minute (rpm) for three minutes. The DPF measurement protocol may require compliance to other operational parameters of the engine during the preparation step.

The DPF measurement protocol also comprises prescriptions for a measurement step for measuring DPF data of the DPF to be diagnosed. The prescriptions comprise a number of measurements to provide to the server as well as setting one or more operational parameters of the engine for each measurement to perform (e.g. engine rpm). The table herebelow (Tab. 1) provides examples of prescriptions for the engine rpm as a function of the engine displacement and the specific measurement for three different measurements.

Tab. 1

Eng. displ.	Measurement 1	Measurement 2	Measurement 3
1.3 L	4500 rpm	4300 rpm	4100 rpm
1.5 L	4000 rpm	3800 rpm	3600 rpm
3.0 L	3500 rpm	3300 rpm	3100 rpm
4.0 L	2500 rpm	2300 rpm	2100 rpm

The DPF measurement protocol may require that the engine is set to the required rpm during a predetermined time (e.g. one minute) before measuring DPF data.
The DPF measurement protocol also takes into account whether the engine of the vehicle is flanged. In particular, the prescriptions with respect to the rpm may be different, e.g. in order to avoid requiring higher rpm than the flanged engine is capable of providing.
The selected DPF measurement protocol is then transmitted 18 to the client terminal by the server.
The client terminal receives 20 the DPF measurement protocol from the server.
In a next step, the DPF measurement protocol is implemented 22: the preparation step and the measurement step described above are implemented, so that the DPF data is compliant to the DPF measurement protocol. The method comprises measuring DPF data including one or more gas mass flows and measuring one or more pressure drops across the DPF at the one or more gas mass flows. A DPF mileage is also collected. The implementation of the DPF measurement protocol may be carried out by workshop personnel and/or automatically by diagnostic boxes connected to the vehicle or a combination thereof.
The measured DPF data are then transmitted 24 to the server by the client terminal and received by the server 25.
Here also, as a further check and tamper protection, the server and/or the client terminal may check that the DPF data are compliant to the DPF measurement protocol (e.g. check whether DPF data are within respective tolerances). For example, if the DPF data are not measured at the predetermined engine rpm (outside the engine rpm tolerance of e.g. 200 rpm, preferably 100 rpm, more preferably 50 rpm) and/or predicted gas mass flows (outside the gas mass flow tolerance of e.g. +/- 20%, preferably +/- 10%, more preferably +/- 5%, of the predicted gas mass flow), the DPF data may be rejected by the server and/or the client terminal. The predicted gas mass flow is based on the engine rpm and the engine displacement. As an additional example, the server and/or the client terminal may check whether the preparation step has been carried out according to the DPF measurement protocol. If any of (or possibly part of) the prescriptions of the DPF measurement protocol are not met, the DPF data maybe rejected.
In a next step, a DPF soot load and a DPF ash load are determined 26. The step of determining the DPF soot load and DPF ash load is schematically depicted in more details in Fig. 3.
For determining the DPF soot load, the received DPF data, including the gas mass flow and the pressure drop, is processed. In case multiple sets of gas mass flows and the pressure drops are received, the following steps are repeated for each of the sets and combined thereafter.
In order to map each pair of gas mass flows and the pressure drops to DPF soot loads, DPFs have been benchmarked to provide calibrated maps mapping a gas mass flow and a pressure drop to a DPF soot load. Maps are calibrated to specific DPFs. Indeed, one DPF may be different from another DPF in that parameters including: channel diameter, channel length, number of channels per square inch, presence or absence of a soot oxidation catalyst coating and presence or absence of a selective catalytic reduction (SCR) catalyst coating (made of e.g. oxides of base metals (such as vanadium, molybdenum and tungsten), zeolites, and/or precious metals) and reducing agent (e.g. aqueous ammonia or urea solution such as AdBlue^®), may differ. Examples of soot oxidation catalysts used in coatings include iron, cerium, strontium, copper, palladium as well as aluminum oxide or a combination thereof. The database is populated with the calibrated maps based on the benchmarked DPFs.
The DPF benchmarks are performed in the following way. New, unloaded DPFs (having different parameters) are connected to an engine and a monitoring of the temperature of the exhaust gas, the mass flow of the exhaust gas and pressure drop across the DPF is implemented. The engine is operated in order to load the DPF with soot. The DPF load is determined by weighing the DPF after leaving the engine running for a predetermined time. The goal is to provide DPFs with a plurality of known loading, e.g. unloaded, lightly loaded state (6 g/L) and clogged state (15 g/L). A denser sampling of DPF loading is also contemplated (e.g. every g/L). An additional broken DPF is also provided in order for the DPF diagnostic method to be able to detect if a DPF to be diagnosed is broken (e.g. pierced).
The response of the DPFs with known loading is then determined with respect to gas mass flows: the pressure drops with respect to a plurality of controlled gas mass flows are determined. In other words, the response of DPFs in terms of pressure drops are probed with controlled gas mass flows. An example of such measurements is provided in Fig. 4 for a particular DPF filter element having a length of 5.66 inches, a diameter of 6 inches, 300 channels per square inch. The measurements are performed at 225°C and at an engine torque of 5 Nm. Fig. 4 shows pressure drops of the particular DPF as a function of the gas mass flow for different loading states.
The measurements for a particular DPF maybe stored as a map (e.g. as a function or as a look-up table). In case of a look-up table is used, the determination of the DPF soot load may comprise interpolating the DPF soot load at the measured mass flow and pressure drop.
The database is also populated with a correspondence between a set of vehicle characteristics and DPFs, thereby allowing for determining which DPF is used based on the vehicle characteristics and, in turn, selecting the associated calibrated map. In case the database is provided with an unknown combination of vehicle characteristics (e.g. an unknown vehicle), a DPF for which the vehicles characteristics are the closest is selected. For determining the closest known vehicle, the server may search in the vehicle characteristics for a vehicle from the same brand, having same or close engine displacement (e.g. +/-1 L, preferably +/- 0.5 L) and the same or close production year (e.g. +/- 2 years, preferably +/- 1 year). In case of unknown combination of vehicle characteristics, warning message may be transmitted to the client terminal indicating that the combination of vehicle characteristic is unknown. Alternatively, the diagnostic method may be aborted.
In an embodiment, the calibrated map may be retrieved from database in conjunction with the DPF measurement protocol.
A DPF soot load is determined by mapping the received mass flow and the pressure drop with the calibrated map. As indicated above, the DPF soot load may be interpolated in case of the determination is based on the look-up table.
In case multiple measurements are required by the DPF measurement protocol, multiple DPF soot loads are determined, as described above, and are combined for providing a DPF soot load back to the client terminal.
The combination of the multiple DPF soot load may be carried out in the following way.
As seen on Fig. 4 which shows pressure drops differences for differently loaded DPFs, pressure drops differences for differently loaded DPFs are greater for higher gas mass flows. In addition, pressure sensors are more accurate in the same region. Therefore, it is advantageous to provide higher weights to measurements at higher gas mass flows. The DPF soot load to be transmitted to the client terminal may be determined by calculating a weighted arithmetic mean. For example, the following weights may be used:

∘ measurement 1: 0.5;
∘ measurement 2: 0.3; and
∘ measurement 3: 0.2,

As indicated above, the DPF diagnostic method is also able to determine whether the DPF is broken in case of a very low pressure drop. In this case, a warning message may be transmitted to the client terminal, e.g. indicating that the DPF is broken and needs replacement.
For determining a DPF ash load, the server processes the received DPF mileage. The ashes mainly originate from engine oil. As the oil consumption of an engine is related to the mileage, the quantity of ashes in the DPF may be inferred from the DPF mileage. Some vehicles are equipped an integrated system for automatic dispensing of a ceria-based fuel-borne catalyst. Ceria mixes with the soot and lowers the oxidation temperature. The DPF ash load is adjusted for taking into account the presence of the integrated system for automatic dispensing of a ceria-based fuel-borne catalyst.

In a subsequent step, the server determines 28 possible one or more DPF servicing measures for improving the operation of the DPF. Several examples of possible DPF servicing measures are provided in the table herebelow (Tab. 2) and depend on the DPF soot load and the DPF ash load.

Tab. 2

Ash load (g/L)	Soot load (g/L)	Recommended servicing measure
[0,26[	///	Replace DPF (DPF detected as missing or pierced due to insufficient pressure drop)
[0,26[	[0,4.8[	No servicing measure
[0,26[	[4.8,6[	Clean the injectors and high pressure pump of the engine with a fuel-borne additive for cleaning the injectors and high pressure pump
[0,26[	[6,15[	Clean the injectors and high pressure pump of the engine with a fuel-borne additive for cleaning the injectors and high pressure pump, and then clean the DPF with an oxidation catalyst as fuel-borne additive
[0,26[	≥ 15	Clean the injectors and high pressure pump of the engine with a fuel-borne additive for cleaning the injectors and high pressure pump, and then clean the DPF with an oxidation catalyst as fuel-borne additive
≥ 26	///	Replace DPF (DPF detected as missing or pierced due to insufficient pressure drop)
≥ 26	[0,4.8[	Manual cleaning of the DPF, then cleaning the injectors and high pressure pump of the engine with a fuel-borne additive for cleaning the injectors and high pressure pump, and clean the DPF with an oxidation catalyst as fuel-borne additive afterwards
≥ 26	[4.8,6[	Manual cleaning of the DPF, then cleaning the injectors and high pressure pump of the engine with a fuel-borne additive for cleaning the injectors and high pressure pump, and clean the DPF with an oxidation catalyst as fuel-borne additive afterwards
≥ 26	[6,15[	Manual cleaning of the DPF, then cleaning the injectors and high pressure pump of the engine with a fuel-borne additive for cleaning the injectors and high pressure pump, and clean the DPF with an oxidation catalyst as fuel-borne additive afterwards
≥ 26	≥ 15	Manual cleaning of the DPF, then cleaning the injectors and high pressure pump of the engine with a fuel-borne additive for cleaning the injectors and high pressure pump, and clean the DPF with an oxidation catalyst as fuel-borne additive afterwards

The DPF servicing measures, the DPF soot load and the DPF ash load are then transmitted 30 to the client terminal. The client terminal receives 32 the DPF servicing measures, the DPF soot load and the DPF ash load. A report is printed 34 for the workshop personnel and the workshop client and at least part of the DPF servicing measures that are suggested by the diagnostic method may be implemented 34. The server may require a confirmation that the manual clean of the DPF is performed, in case it was recommended. This is advantageous since the server may then take into account that a particular DPF has been manually clean for the next DPF diagnostic method (e.g. the DPF mileage may be determined relatively to the previous manual clean mileage).
While specific embodiments have been described herein in detail, those skilled in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Claims

A diesel particulate filter (DPF) diagnostic method, comprising:
receiving, by a server, DPF data comprising a pressure drop across the DPF;

determining, by the server, a DPF soot load by processing the pressure drop; and

transmitting, by the server, the determined DPF soot load to a client terminal;

wherein further DPF data comprising a gas mass flow is received by the server, the pressure drop being obtained at the gas mass flow, the DPF soot load being determined by processing both the pressure drop and the gas mass flow, wherein the gas mass flow is a gas mass flow at the inlet of the DPF or an engine intake gas mass flow.
The DPF diagnostic method according to claim 1, wherein the server has electronic access to a map mapping a pressure drop and a gas mass flow to a DPF soot load, wherein the server determines the DPF soot load by using the map for processing the pressure drop and gas mass flow.
The DPF diagnostic method according to any one of claims 1 to 2, wherein DPF soot loads with respect to pressure drops and to gas mass flows are stored in a look-up table, the processing of both the pressure drop and the gas mass flow comprising querying the look-up table for a DPF soot load at the pressure drop and the gas mass flow.
The DPF diagnostic method according to any one of claims 1 to 3, wherein the received DPF data comprises at least two sets of pressure drops and gas mass flows, each of the at least two set being for different gas mass flows, the DPF soot load being determined by processing the at least two sets of pressure drop and gas mass flow.
The DPF diagnostic method according to claim 4, wherein the determination of the DPF soot load comprises assigning a higher weight to one or more sets of the at least two sets having a higher gas mass flow.
The DPF diagnostic method according to any one of claims 1 to 5, comprising:
determining DPF data, including:
∘ measuring a gas mass flow; and

∘ measuring a pressure drop across the DPF at the gas mass flow;

wherein the measured gas mass flow and the measured pressure drop are compliant to a DPF measurement protocol agreed upon with the server and the client terminal;

transmitting the determined DPF data to the server, the transmission being effected by the client terminal; and

receiving, by the client terminal, the determined DPF soot load from the server.
The DPF diagnostic method according to claim 6, further comprising:
transmitting, to the server, a DPF mileage, the transmission being effected by the client terminal; and

receiving, by the client terminal, a DPF ash load from the server.
The DPF diagnostic method according to any one of claims 6 to 7, wherein the DPF measurement protocol comprises prescriptions so as to determine the pressure drop at a predetermined gas mass flow, the prescriptions setting one or more operational parameters of an engine to which the DPF is in fluid communication with, the engine having an engine displacement, the one or more operational parameters comprising a predetermined engine revolutions per minute (rpm) with respect to the engine displacement so as to provide the predetermined gas mass flow.
The DPF diagnostic method according to any one of claims 6 to 8, wherein the DPF measurement protocol prescribes a predetermined exhaust gas temperature for measuring the gas mass flow and the pressure drop, preferably the predetermined exhaust gas temperature is comprised in the interval from 200°C to 250°C, more preferably the predetermined exhaust gas temperature is comprised in the interval from 220°C to 230°C.
The DPF diagnostic method according to any one of claims 1 to 9, wherein the determination of the DPF soot load is further based on at least one of a DPF geometry (e.g. channel diameter, channel length, number of channels per square inch), an indicator of whether the DPF comprises a soot oxidation catalyst and an indicator of whether a selective catalytic reduction (SCR) catalyst coating and reducing agent are used.
The DPF diagnostic method according to any one of claims 1 to 10, wherein the server comprises, or is in communication with, a database including automotive vehicle characteristics of automotive vehicles, the automotive vehicle characteristics being selected from the group consisting of a vehicle registration number, a date of entry into service, vehicle brand, vehicle model, compliance to a European emission standard, an engine model, an engine displacement, an engine power, an indicator of whether the engine is flanged;
the method further comprising:
receiving, by the server, one or more of the automotive vehicle characteristics;

wherein the determination of the DPF soot load being carried out on the basis of the received one or more of the automotive vehicle characteristics.
The DPF diagnostic method according to claim 10, wherein the DPF data further comprises a mileage of the DPF and the automotive vehicle characteristics comprise an indicator of whether the automotive vehicles comprise an integrated system for automatic dispensing of a ceria-based fuel-borne catalyst;
the method further comprising:
determining, by the server, a DPF ash load, the DPF ash load being determined on the basis of the mileage of the DPF;

wherein the determination of the DPF ash load is adjusted for taking into account the presence of the integrated system in case the indicator indicates that the integrated system is present; and

transmitting, by the server, the determined DPF ash load to the client terminal.
The DPF diagnostic method according to claim 12, comprising selecting a map mapping a pressure drop and a gas mass flow to a DPF soot load, the map preferably being stored in the database, the selection being based on the received one or more of the automotive vehicle characteristics, the selected map being calibrated for the received one or more of the automotive vehicle characteristics, wherein the DPF soot load is determined on the basis of the selected map.
The DPF diagnostic method according to any one of claims 12 to 13, comprising selecting a DPF measurement protocol based one the received one or more of the automotive vehicle characteristics, the DPF measurement protocol preferably being stored in the database; the DPF measurement protocol being calibrated for the received one or more of the automotive vehicle characteristics, and
transmitting the selected DPF measurement protocol to the client terminal.
The DPF diagnostic method according to any one of claims 12 to 14, comprising:
collecting at least one of the automotive vehicle characteristics;

transmitting the collected to automotive vehicle characteristics the server, the transmission being effected by the client terminal; and

receiving the DPF measurement protocol from the server.
A computer program comprising instructions, which, when executed by a computer, cause the computer to carry out the method as claimed in any one of claims 1 to 15.
A computer program product comprising a computer readable medium having stored thereon a computer program according to claim 16.