WO2016007079A1

WO2016007079A1 - Method and system to determine the need for cleaning of a particulate filter

Info

Publication number: WO2016007079A1
Application number: PCT/SE2015/050804
Authority: WO
Inventors: Daniel Hjortborg; David Raymand
Original assignee: Scania Cv Ab
Priority date: 2014-07-07
Filing date: 2015-07-07
Publication date: 2016-01-14
Also published as: SE540518C2; BR112016028120A2; DE112015002694T5; SE1450859A1

Abstract

The present invention relates to a method for determination of a cleaning need relating to a particulate filter (265) in the exhaust treatment system of an engine (231), from the point of view of ash occurrence, comprising the steps to: - determine a measure of accumulated ash occurrence in said particulate filter (265), and - determine (s340) said measure based on a determined heat capacity (C1; C2) of said particulate filter (265) in at least two different states, relating to accumulated ash occurrence.

Description

Method and system to determine the need for cleaning of a particulate filter

TECHNICAL FIELD The invention relates to a method for determination of a cleaning need relating to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence. The invention also relates to a computer program product, comprising program code for a computer, to implement a method according to the invention. The invention also relates to a system for determination of a cleaning need relating to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence, and a motor vehicle equipped with such system.

BACKGROUND Exhaust treatment systems in motor vehicles today comprise a number of different components. For example, an exhaust treatment system may comprise a DOC-unit (Diesel Oxidation Catalyst) arranged in a passage downstream of a combustion engine in the vehicle. Other components that may be arranged downstream of said engine are a DPF-unit (Diesel Particulate Filter) and an SCR-catalyst (Selective Catalytic Reduction).

For many reasons, it is desirable to be able to diagnose individual components in an exhaust treatment system of motor vehicles, such as for example trucks and buses. Diagnosis of components in exhaust treatment systems of motor vehicles may, for example, be desirable to be able to determine the prevailing performance and/or function of the different components. Diagnosis of individual components in exhaust treatment systems may in certain countries be subject to laws, regulations or directives, which vehicle manufacturers must obviously comply with, not at least from an environmental and a competition point of view.

Said DPF-unit is arranged to catch e.g. soot and ash from an engine. Said soot and ash may originate from the engine's fuel or from lubricant in the engine. Soot comprises combustible materials, while ash does not comprise combustible materials. Soot is a term referring to the combustion residues formed when there is an excess of carbon in relation to oxygen. Ash is the solid residual product following combustion of organic substances. Soot may thus be burned at least partly, while ash may not be burned. Ash may be the non-combustible part of soot.

When soot and ash are stored in said DPF-unit, a back pressure increases in the exhaust treatment system. This contributes to unwanted parasitic losses of the system, where work is required to squeeze the exhaust gases from the engine through said DPF-unit. This either results in a drive power reduction of the vehicle's powertrain, or in an increased fuel consumption of the engine, in order to maintain the desired drive power of said powertrain.

With certain intervals, said DPF-unit may be actively regenerated to reduce or substantially eliminate the amount of stored soot. However, stored soot needs to be removed at somewhat regular intervals from said DPF-unit, for example manually with compressed air. This method is time consuming, expensive and often difficult to carry out for service staff.

Today, a level of ash deposits in said DPF-unit may be determined by way of so-called dead counting, whereby said level of ash deposits is calculated continuously according to a predetermined calculation model. This method may be based on an average value relating to deposit capacity for a number of different individual vehicles, and thus has shortcomings in accuracy for application in specific individual vehicles. It should also be pointed out that the oil consumption of engines varies widely between individual vehicles and has a significant variation over time. Therefore, today it is problematic to determine relevant intervals for service or replacement of DPF-units in exhaust treatment systems, for example in motor vehicles.

US20080264045 describes a method to determine whether regeneration of a particulate filter in an exhaust treatment system is sufficient, or whether said particulate filter needs service. According to this method, a pressure difference is measured over the particulate filter, in order to measure a filling degree. Additionally, an electric resistance is measured over said particulate filter, in order to determine whether or not there is ash stored in said particulate filter.

OBJECTIVE OF THE INVENTION

Accordingly, there is a need to reliably determine a cleaning need of a DPF- unit in an exhaust treatment system of a motor vehicle.

There is a need to diagnose, in an efficient, reliable and user-friendly manner, a DPF-unit in terms of performance.

One objective of the present invention is to achieve a novel and advantageous method for determination of a cleaning need relating to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence. One objective of the present invention is to provide a novel and advantageous method for performance control of a DPF-unit in an exhaust treatment system.

Another objective of the invention is to provide a novel and advantageous system for the determination of a cleaning need relating to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence, and a novel and advantageous computer program for the determination of a cleaning need in relation to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence.

Another objective of the invention is to provide an alternative method for the determination of a cleaning need in relation to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence, an alternative system for the determination of a cleaning need in relation to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence, and an alternative computer program to control a method for the determination of a cleaning need in relation to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence.

Yet another objective of the invention is to provide a method regarding an exhaust treatment system, a device regarding an exhaust treatment system and a computer program to achieve a reliable performance control of a DPF- unit in a motor vehicle.

Yet another objective of the invention is to provide a method at regarding exhaust treatment system, a device regarding an exhaust treatment system and a computer program to achieve a reliable performance control of a DPF- unit in an SCR-system, which SCR-system may be installed in a motor vehicle.

SUMMARY OF THE INVENTION

These and other objectives, which are set out in the description below, are achieved with a method, a system, a motor vehicle, a computer program and a computer program product of the type specified above, and which further have the features specified in the characterising portion of the appended independent claims. The preferred embodiments of the method and the system are defined in the attached non-independent claims. The embodiments of the system have advantages corresponding to the embodiments for the above, described method.

According to one aspect of the present invention a method for the determination of a cleaning need in relation to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence, is provided. The method comprises the steps to:

- determine a measure of accumulated , occurrence in said particulate filter; and

- determine said measure based on the determined heat capacity of said particulate filter, in at least two different states, with respect to accumulated ash occurrence.

A first measuring value is determined in a first state where no, or substantially no, ash is present in said particulate filter. This constitutes a reference state and reflects a heat capacity of said particulate filter without any stored ash. A second measuring value is determined in a second state, when accumulated ash has been stored in said particulate filter. This constitutes a state reflecting a heat capacity of said particulate filter, when there is stored ash. By comparing these two measuring values, ash occurrence may be determined in a simple, user-friendly, robust and reliable manner according to the innovative method. Furthermore, the innovative method is adapted to the specific, individual vehicle/engine, wherein said particulate filter is arranged.

The method may comprise the steps to:

- determine a first value of said heat capacity of said particulate filter, based on a first state comprising determined parameter values relating to exhaust mass flow from said engine, and a temperature difference relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter, and an expected low ash occurrence; - determine a second value of said heat capacity of said particulate filter, based on a determination of said first value of said heat capacity, and on a second state comprising determined parameter values relating to exhaust mass flow from said engine, and a temperature difference relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter, and an expected higher ash occurrence in relation to said first state; and

- determine said measure, based on a comparison between the thus determined two values of said heat capacity. Said comparison may comprise comparing an absolute difference, or an absolute quota relating to the thus determined two values for said heat capacity, with one respective adequate threshold value.

By considering a temperature inertia of the particulate filter, which inertia depends to a great extent on the amount of ash deposited, said measure of the accumulated ash occurrence in said particulate filter may be determined in a user-friendly and reliable manner. The thermal inertia of said particulate filter is due to the amount of stored soot and ash. Here, it is important to point out that stored ash has a great impact on the thermal inertia of the particulate filter in relation to a stored amount of soot. The density of the ash is in the range of 10 times higher than that of soot.

By determining heat energies, based on prevailing exhaust mass flows and said temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter for said two different states, the equation below may be used, according to one aspect of the present invention.

MF1 x CI x |Δ7Ί | = MF2 x C2 x |ΔΓ₂ |

Herewith, a first heat energy is determined in the system in a first state, by multiplying a prevailing exhaust mass flow MF1 with a measure of a heat capacity C1 and an absolute difference lATj between said exhaust temperatures upstream and downstream, respectively, of said particulate filter. Said first measure of the heat capacity C1 may be determined in a suitable manner, when substantially no ash is present in said particulate filter. This may, for example, be carried out when the vehicle is leaving a manufacturing plant.

Here, said second measure of a heat capacity C2, in a second state, may be calculated by way of said energy correlation, based on a determined second exhaust mass flow MF2 and an absolute difference |ΔΓ₂ | between said exhaust temperatures upstream and downstream, respectively, of said particulate filter in said second state.

The method comprises the step to:

- determine said values of said heat capacity in connection with transients, relating to the exhaust temperature upstream and/or downstream of said particulate filter; and/or - determine said values of said heat capacity, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter exceeds a predetermined value. Here, a careful manner of determining a measure of the accumulated ash occurrence in said particulate filter is provided. The method may comprise the step to :

- regenerate said particulate filter regarding soot particles, before said measure relating to accumulated ash occurrence is determined. Hereat, said particulate filter advantageously comprises only ash, which provides a reliable method to determine ash occurrence in said particulate filter. The method may comprise the step to:

- predict a need to remove ash from said particulate filter, based on a determination of the development of said measure over time. Hereat, an operator of said engine may, with an exhaust treatment system comprising a particulate filter, become aware and plan in advance to clean or replace said particulate filter. Advantageously, more adequate service intervals for said particulate filter may be provided compared to prior art technology. This entails a reduced risk of storing excessively large amounts of ash in the particulate filter, which is advantageous from the point of view of, among others, performance.

The method may comprise the steps to:

- determine the need to remove accumulated ash from said particulate filter at a predetermined value reached with respect to said measure; and

- at a determined need to remove accumulated ash from said particulate filter, indicate said need to the operator of said engine. Hereat, an operator of said engine may, with an exhaust treatment system comprising a particulate filter, become aware and plan in advance to clean or replace said particulate filter. Advantageously, more adequate service intervals for said particulate filter may be provided compared to prior art technology. This entails a reduced risk of storing excessively large amounts of ash in the particulate filter, which is advantageous from the point of view of, among others, performance. According to one aspect of the present invention, a system for the determination of a cleaning need in relation to a particulate filter in the exhaust treatment system of an engine, from the point of view of ash occurrence, is provided, comprising:

- elements adapted to determine a measure of the occurrence of accumulated ash in said particulate filter; and

- elements adapted to determine said measure, based on the determined heat capacity of said particulate filter in at least two different states, with respect to accumulated ash occurrence. The system may comprise:

- elements adapted to determine a first value of said heat capacity of said particulate filter, based on a first state comprising determined parameter values relating to exhaust mass flow from said engine, and a temperature difference relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter, and an expected low ash occurrence;

- elements adapted to determine a second value of said heat capacity of said particulate filter, based on a determination of said first value of said heat capacity, and on a second state comprising determined parameter values relating to exhaust mass flow from said engine, and a temperature difference relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter, and an expected higher ash occurrence in relation to said first state; and - elements adapted to determine said measure, based on a comparison between the thus determined two values of said heat capacity.

The system comprises:

- elements adapted to determine said values of said heat capacity in connection with transients relating to the exhaust temperature upstream and/or downstream of said particulate filter; and/or

- elements adapted to determine said values of said heat capacity, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter exceeds a predetermined value. The system may comprise: - elements adapted to regenerate said particulate filter with respect to soot particles, before said measure relating to accumulated ash occurrence is determined.

The system may comprise: - elements adapted to predict a need to remove ash from said particulate filter, based on a determination of the development of said measure over time.

The system may comprise:

- elements adapted to determine the need to remove accumulated ash from said particulate filter at a predetermined value reached with respect to said measure; and

- elements adapted, at a determined need to remove accumulated ash from said particulate filter, to indicate said need to the operator of said engine.

According to one aspect of the present invention, a motor vehicle is provided, comprising a system according to any of the claims 7-12.

The motor vehicle may be a truck, a bus or a car.

According to one aspect of the present invention, a computer program is provided in an exhaust treatment system, wherein said computer program comprises program code to cause an electronic control device or a computer, connected to the electronic control device, to perform the steps according to any of claims 1 -6.

According to one aspect of the present invention, a computer program is provided in an exhaust treatment system, wherein said computer program comprises program code to cause an electronic control device or a computer, connected to the electronic control device, to perform the steps according to any of claims 1 -6, when said program code is executed in said control device or said computer.

According to one aspect of the present invention, a computer program is provided in an exhaust treatment system, wherein said computer program comprises program code stored on a computer readable medium, in order to cause an electronic control device or a computer, connected to the electronic control device, to perform the steps according to any of claims 1 -6.

According to one aspect of the present invention, a computer program is provided in an exhaust treatment system, wherein said computer program comprises program code stored on a computer readable medium, to cause an electronic control device or a computer, connected to the electronic control device, to perform the steps according to any of claims 1 -6, when said program code is executed in said control device or said computer. According to one aspect of the present invention, a computer program product comprising program code stored in a computer readable medium is provided, in order to perform the method steps according to any of claims 1 - 6, wherein said program code is executed in an electronic control device or in a computer connected to the electronic control device. According to one aspect of the present invention, a computer program product, comprising program code stored in a non-volatile way in a computer- readable medium, is provided to perform the method steps according to one or several of the aspects above, when said program code is executed in an electronic control device or in another computer connected to the electronic control device.

Additional objectives, advantages and novel features of the present invention will be apparent to one skilled in the art from the following details, and through exercising the invention. While the invention is described below, it should be apparent that the invention is not limited to the specifically described details. One skilled in the art, having access to the teachings herein, will recognise additional applications, modifications and incorporations in other areas, which are within the scope of the invention.

BRIEF DESCRIPTION OF THE FIGURES The present invention will be understood more easily with reference to the following detailed description, read in conjunction with the enclosed drawings, where the same reference numerals refer to the same parts throughout the several views, and in which:

Figure 1 schematically illustrates a vehicle, according to one embodiment of the invention;

Figure 2 schematically illustrates a sub-system of the vehicle displayed in Figure 1 , according to one embodiment of the invention;

Figure 3a schematically illustrates a flow chart of a method, according to one embodiment of the invention;

Figure 3b schematically illustrates in more detail a flow chart of a method, according to one embodiment of the invention; and

Figure 4 schematically illustrates a computer, according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE FIGURES A side view of a vehicle 100 is shown with reference to Figure 1 . The exemplary vehicle 100 consists of a tractor 1 10 and a trailer 1 12. The vehicle may be a heavy goods vehicle, such as a truck or a bus. The vehicle may, alternatively, be a car.

The term "link" herein refers to a communications link, which may be a physical line, such as an opto-electronic communication line, or a non- physical line, such as a wireless connection, e.g. a radio or microwave link. The terms "reducing agent" or "reductant", as used herein, means a substance used to react with certain emissions in an SCR system of the engine's exhaust treatment system. These emissions may be e.g. NOx-gas. The said reductant is, according to one embodiment, also known as AdBlue. Obviously other types of reductants may be used.

It should be pointed out that the invention is suitable for application in a suitable exhaust treatment system, comprising a DPF-unit. The method according to the invention and the system according to the invention are well suited to other platforms than motor vehicles, comprising an exhaust treatment system, such as e.g. watercraft. The watercraft may be of any suitable type, such as motor boats, ships, ferries or vessels.

The innovative method and the system according to the invention for an exhaust treatment system according to one aspect of the invention, are also suitable for e.g. systems comprising tractors, dump trucks, machinery, industrial engines and/or engine powered industrial robots.

The innovative method and the system according to the invention regarding an exhaust treatment system according to one aspect of the invention, are also suitable for different types of power plants, e.g. electric power plants comprising a diesel generator. The innovative method and the system according to the invention regarding an exhaust treatment system are well suited for any suitable engine system, comprising an engine, a DPF-unit and potentially an SCR system, e.g. in a locomotive or another platform.

The innovative method and the system according to the invention regarding an exhaust treatment system are well suited for a system comprising a NOx generator and a DPF-unit, e.g. a diesel engine whose exhausts must be purified. Fig. 2 schematically illustrates a sub-system 289 of the vehicle 100 shown in Figure 1 , according to one embodiment of the invention. Said sub-system 289 constitutes a part of an exhaust treatment system in the vehicle 100.

An engine 231 is provided, which at operation causes an exhaust flow, which is led via a first passage 235 to a DOC-device 260. A second passage 245 is arranged to lead exhausts from said DOC-device 260 to a DPF-device 265. Said DPF-device 265 comprises a diesel particulate filter. A third passage 255 is arranged to lead exhausts from said DPF-device 265 to an SCR- catalyst arrangement 270. Said SCR-catalyst arrangement 270 may alternatively be referred to as an SCR-catalyst. A fourth passage 256 is arranged to lead exhausts from said SCR-catalyst arrangement 270 to the environment surrounding the vehicle 100.

According to one alternative embodiment, said DOC-device 260 and/or said SCR-catalyst 270 may be omitted.

In the event said exhaust treatment system comprises an SCR-catalyst 270, a dosage device (not displayed) is provided, which is arranged to administer reductant into said third passage 255 for catalytic exhaust purification relating to NOx-gas. The first control device 200 is arranged for communication with the engine 231 via a link L231 . The first control device 200 is arranged to control the operation of said engine 231 . The first control device 200 is arranged to e.g. control the dosage of fuel to the combustion chambers in said engine 231 .

Fuel dosage elements (not displayed) may be arranged upstream of said DOC-device 260 and downstream of said engine 231 . The first control device 200 is arranged for communication with said fuel dosage element via a link intended for this purpose (not displayed). The first control device 200 is arranged to control the dosage of fuel, for example diesel, into said first passage 235 with said fuel dosage element, in order to achieve a so-called active regeneration of said DPF-unit 265.

A first temperature sensor 237 is arranged upstream of said DPF-device 265 at said second passage 245. Said first temperature sensor 237 is arranged for communication with the first control device 200 via a link L237. Said first temperature sensor 237 is arranged to continuously measure/detect/determine a prevailing temperature T1 of the exhausts in the second passage 245. Said first temperature sensor 237 is arranged to continuously send signals S237, comprising information about said prevailing first temperature T1 of the exhausts in said second passage 245, via the link L237, to the first control device 200.

A second temperature sensor 277 is arranged downstream of said DPF- device 265 at said third passage 255. Said second temperature sensor 277 is arranged for communication with the first control device 200 via a link L277. Said second temperature sensor 277 is arranged to continuously measure/detect/determine a prevailing second temperature T2 of the exhausts in the third passage 255. Said second temperature sensor 277 is arranged to continuously send signals S277, comprising information about said prevailing second temperature T2 of the exhausts in said third passage 255, via the link L277, to the first control device 200.

According to one example embodiment, a third temperature sensor 233 may be arranged upstream of said DOC-device 260 at said first passage 235. Said third temperature sensor 233 is arranged for communication with the first control device 200 via a link L233. Said first temperature sensor 233 is arranged to continuously measure/detect/determine a prevailing third temperature T3 of the exhausts in the first passage 233. Said third temperature sensor 233 is arranged to continuously send signals S233, comprising information about said prevailing third temperature T3 of the exhausts in said first passage 233, via the link L233, to the first control device 200. According to one aspect of the present invention, said first temperature T1 and said second temperature T2 are used to determine a temperature difference over said DPF-device 265, whereby a prevailing heat capacity may be determined according to the innovative method. According to an alternative embodiment, said third temperature T3 and said second temperature T2 may be used to determine a temperature difference over said DPF-device 265 and said DOC-device, whereby a prevailing heat capacity for the combination of said DPF-device 265 and said DOC-device 260 may be determined and used in a congruent manner (in relation to the use of the temperatures T1 and T2), according to one aspect of the innovative method. This embodiment is not described in any further detail herein.

A sensor (not displayed) for measuring a prevailing exhaust mass flow MF may be arranged in the first passage 235. Said exhaust mass flow sensor is arranged to continuously determine a prevailing exhaust mass flow MF in the first passage 235, and to send signals comprising information thereof to the first control device 200 via a link intended for this purpose (not displayed).

According to one embodiment, the first control device 200 is arranged to, via a calculation model stored therein, determine a prevailing exhaust mass flow MF in the first passage 235. Said prevailing exhaust mass flow MF in the first passage 235 may be determined based on e.g. a determined operating mode of the engine 231 .

An exhaust gas mass flow determined in said first state (when substantially no ash is stored in said DPF-device 265) is referred to herein as MF1 , and an exhaust gas mass flow determined in said second state (when a certain amount of ash is stored in said DPF-device 265) is referred to herein as MF2.

The first control device 200 may be arranged to determine a measure of accumulated ash occurrence in said particulate filter 265. This may be carried out by determining said measure, based on the determined heat capacity of said particulate filter 265 in at least two different states with respect to accumulated ash occurrence.

The first control device 200 may be arranged to determine a first value C1 of said heat capacity of said particulate filter 265, based on a first state comprising determined parameter values relating to exhaust mass flow MF1 from said engine 231 , and a temperature difference T1 -T2 or T3-T2 relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter 265, and an expected low ash occurrence.

The first control device 200 may be arranged to determine a second value C2 of said heat capacity of said particulate filter 265, based on the determination of said first value C1 for said heat capacity and on a second state comprising determined parameter values relating to exhaust mass flow MF2 from said engine 231 , and a temperature difference T1 -T2 or T3-T2 relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter 265, and an expected higher ash occurrence in relation to said first state.

The first control device 200 may be arranged to determine said measure based on a comparison between the thus determined two values C1 and C2 for said heat capacity. The first control device 200 may be arranged to determine said measure based on a comparison between an absolute difference, |C1- C2| , between the thus determined two values C1 and C2 and a predetermined threshold value TH1 . In the event said absolute difference between the thus determined two values C1 and C2 exceeds said threshold value TH1 , this is treated as an indication that said particulate filter 265 should/must be cleaned or replaced within a certain time period, for example substantially immediately, as soon as possible or after a maximum number of operating hours with the engine 231 , for example 10, 100 or 200 hours. The first control device 200 may be arranged to determine said measure, based on a comparison between an absolute quota C1/C2 between the thus determined two values C1 and C2 and a predetermined threshold value TH2. In the event said absolute quota C1/C2 between the thus determined two values C1 and C2 falls short of said threshold value TH2, this is treated as an indication that said particulate filter 265 should/must be cleaned or replaced within a certain time period, for example substantially immediately, as soon as possible or after a maximum number of operating hours with the engine 231 , for example 10, 100 or 200 hours.

The first control device 200 may be arranged to determine said values C1 and C2 for said heat capacity in connection with transients in relation to the exhaust temperature T1 or T3, upstream of said particulate filter 265. The first control device 200 may be arranged to determine said values C1 and C2 for said heat capacity in connection with transients in relation to the exhaust temperature T2 downstream of said particulate filter. The first control device 200 may be arranged to determine a suitable point in time for determining said values C1 and C2, based on the prevailing operating condition of the engine 231 , whereat said operating condition advantageously comprises transient temperature processes in relation to said exhaust temperature and/or exhaust mass flow MF.

The first control device 200 may be arranged to determine said values C1 and C2 for said heat capacity, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter exceeds a predetermined value THtemp. Said predetermined value THtemp may be any suitable value. Said predetermined value THtemp is a non-zero value, for example 10, 50 or 100 degrees Celsius. Generally, a greater value for THtemp is better than a lower value. The first control device 200 may be arranged to regenerate said particulate filter 265 with respect to soot particles, before said measure relating to accumulated ash occurrence is determined.

The first control device 200 may be arranged to predict a need to remove ash from said particulate filter 265, based on a determination of the development of said measure over time.

The first control device 200 may be arranged to determine a need to remove accumulated ash from said particulate filter 265 at predetermined, achieved value for said measure. The first control device 200 may be arranged, at a determined need to remove accumulated ash from said particulate filter 265, to indicate said need to the operator of said engine 231 . This may occur via presentation elements 220.

The presentation elements 220 are arranged for communication with said first control device 200 via a link L220. The first control device 200 is arranged to present a result of the performance control of said DPF-device 265. Said result may for example specify "no occurrence of ash in the DPF- device", "low occurrence of ash in the DPF-device", "average occurrence of ash in the DPF-device, cleaning soon is recommended", or "high occurrence of ash in the DPF-device, cleaning/replacement should be carried out immediately". For example, a degree of ash occurrence/functional impairment in said DPF-device 265 may be presented, and such degree of ash occurrence/functional impairment may be specified as a percentage. Said presentation elements 220 may comprise speakers to render a synthesised voice or other audio feedback. Said presentation elements 220 may comprise a display screen, for example a so-called touch screen for visual feedback of said result.

A second control device 210 is arranged for communication with the first control unit 200 via a link L210. The second control device 210 may be detachably connected to the first control device 200. The second control device 210 may be a control unit external to the vehicle 100. The second control device 210 may be arranged to carry out the method steps according to the invention. The second control device 210 may be used to transfer program code to the first control device 200, in particular program code to perform the method according to the invention. Alternatively, the second control device 210 may be arranged for communication with the first control device 200 via an internal network in the vehicle. The second control device 210 may be arranged to carry out substantially similar functions as the first control device 200. Figure 3a illustrates schematically a flow chart of a method for determination of a cleaning need with respect to a particulate filter 265 in the exhaust treatment system of an engine 231 , from the point of view of ash occurrence. The method comprises a method step s301 . The step s301 comprises the steps to: - determine a measure of accumulated ash occurrence in said particulate filter 265,

- determine said measure, based on a determined heat capacity C1 , C2 of said particulate filter 265 in at least two different states relating to accumulated ash occurrence. Following the method step s301 the method is completed.

Fig. 3b illustrates schematically in further detail a flow chart of a method for determination of a cleaning need with respect to a particulate filter 265 in the exhaust treatment system of an engine 231 , from the point of view of ash occurrence. The method comprises a method step s310. The method step s310 comprises the step, in a first state, to determine a prevailing exhaust mass flow MF1 from said engine 231 . This may be done with a suitable sensor or with a calculation model, which is stored in a memory in the first control device 200. The method step s310 comprises the step, in a first state, to determine a first or a third temperature value T1 , T3 downstream of said engine 231 and upstream of said particulate filter 265. The method step s310 comprises the step, in a first state, to determine a second temperature value T2 downstream of said particulate filter 265. This may be done with a suitable sensor or with a calculation model, which is stored in a memory in the first control device 200.

The method step s310 comprises the step of determining a first value C1 of said heat capacity of said particulate filter 265, based on said first state comprising determined parameter values with respect to the exhaust mass flow MF1 from said engine 231 , and at least one of said temperature differences T1 -T2, T3-T2 with respect to the exhaust temperature upstream and downstream, respectively, of said particulate filter 265, and an expected low ash occurrence. By using the energy expression MFI x CI x lATj and a suitable constant, said first value C1 may be determined. The absolute amount lATj relates to a first temperature difference in the first state, where lATj is equal to the temperature difference T1 -T2 or T3-T2.

Said value C1 of said heat capacity may be determined in connection with transient processes relating to the exhaust temperature upstream and/or downstream of said particulate filter 265.

Said value C1 of said heat capacity may be determined, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter 265 exceeds a predetermined value THtemp. Following the method step s310, a subsequent method step s320 is completed.

The method step s320 comprises the step, in a second state, to determine a prevailing exhaust mass flow MF2 from said engine 231 . This may be done with a suitable sensor or with a calculation model, which is stored in a memory in the first control device 200.

The method step s320 comprises the step, in a second state, to determine a first or a third temperature value T1 , T3 downstream of said engine 231 and upstream of said particulate filter 265. The method step s320 comprises the step, in a second state, to determine a second temperature value T2 downstream of said particulate filter 265. This may be done with a suitable sensor or with a calculation model, which is stored in a memory in the first control device 200. The method step s320 comprises the step to determine a second value C2 of said heat capacity of said particulate filter 265, based on the determination of said first value C1 for said heat capacity, and on a second state comprising determined parameter values relating to exhaust mass flow MF2 from said engine 231 , and a temperature difference T1 -T2 or T3-T2 relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter 265, and an expected higher ash occurrence in relation to said first state.

By using the energy expression

MF1 x CI x \AT \ = MF2 x C2 x |ΔΓ₂ | the second value C2 may be resolved. The absolute amount |ΔΓ₂ | relates to a first temperature difference in the second state, where |ΔΓ₂ | is equal to the temperature difference T1 -T2 or T3- T2.

Said value C2 of said heat capacity may be determined in connection with transient processes relating to the exhaust temperature upstream and/or downstream of said particulate filter 265. Said transient processes in relation to the exhaust temperature may be associated with transient processes of said exhaust mass flow from said engine 231 .

Said value C2 of said heat capacity may be determined, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter 265 exceeds a predetermined value THtemp.

Following the method step s320, a subsequent method step s330 is completed. The method step s330 comprises the step of comparing the thus determined two values C1 , C2 for said heat capacity. Here, an absolute difference between C1 and C2 may be compared with a predetermined threshold value TH1 . Here, an absolute quota between C1 and C2 may be compared with a predetermined threshold value TH2. Following the method step s330, a subsequent method step s340 is completed.

The method step s340 comprises the step of determining said measure of accumulated ash occurrence in said particulate filter 265, based on said comparison of the determined heat capacities C1 and C2 of said particulate filter 265 in said at least two different states, with respect to accumulated ash occurrence.

The method step s340 may comprise the step to determine a need to remove accumulated ash from said particulate filter 265 at a predetermined, achieved value for said measure. Following the method step s340, a subsequent method step s350 is completed. The method step s350 may comprise the step of, at a determined need to remove accumulated ash from said particulate filter, presenting/indicating said need to the operator of said engine 231 or vehicle 100. This may occur via said presentation elements 220. The method is completed after step s350.

With reference to Figure 4, a diagram of an embodiment of a device 500 is shown. The control devices 200 and 210, which are described with reference to Figure 2, may in one embodiment comprise the device 500. The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory part 530, wherein a computer program, such as an operating system, is stored to control the function of the unit 500. Further, the unit 500 comprises a bus controller, a serial communications port, an I/O device, an A D converter, a date-time input and transmission unit, an event counter and an interrupt controller (not shown). The non-volatile memory 520 also has a second memory part 540.

A computer program P is provided for determination of a cleaning need relating to a particulate filter 265 in the exhaust treatment system of an engine 231 , from the point of view of ash occurrence. The computer program P may comprise procedures to determine a measure of accumulated ash occurrence in said particulate filter 265.

The computer program P may comprise procedures to determine said measure, based on a determined heat capacity C1 , C2 of said particulate filter 265 in least two different states relating to accumulated ash occurrence.

The computer program P may comprise procedures to determine a first value C1 of said heat capacity of said particulate filter 265, based on a first state comprising determined parameter values relating to exhaust mass flow MF1 from said engine 231 , and a temperature difference T1 -T2 or T3-T2 relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter 265, and an expected low ash occurrence.

The computer program P may comprise procedures to determine a second value C2 for said heat capacity of said particulate filter 265, based on the determination of said first value C1 for said heat capacity and on a second state comprising determined parameter values with respect to the exhaust mass flow MF2 from said engine 231 , and a temperature difference T1 -T2, T3-T2 with respect to the exhaust temperature upstream and downstream, respectively, of said particulate filter 265, and an expected higher ash occurrence in relation to said first state. The computer program P may comprise procedures to determine said measure based on a comparison between the thus determined two values for said heat capacity C1 , C2. This may be carried out by comparing an absolute difference between said first heat capacity C1 and said second heat capacity C2 with a predetermined value TH1 . This may be carried out by comparing an absolute quota between said first heat capacity C1 and said second heat capacity C2 with a predetermined value TH2.

The computer program P may comprise procedures to determine said values C1 , C2 for said heat capacity in connection with transient processes in relation to the exhaust temperature upstream of said particulate filter 265; and/or

- procedures to determine said values C1 , C2 for said heat capacity, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter 265 exceeds a predetermined value THtemp.

The computer program P may comprise procedures to determine said values C1 , C2 for said heat capacity in connection with transient processes in relation to the exhaust temperature downstream of said particulate filter. The computer program P may comprise procedures to control the regeneration of said particulate filter 265 with respect to soot particles, before said measure relating to accumulated ash occurrence is determined.

The computer program P may comprise procedures to predict a need to remove ash from said particulate filter 265, based on a determination of the development of said measure over time.

The computer program P may comprise procedures to determine the need to remove accumulated ash from said particulate filter 265 at a predetermined value reached with respect to said measure; and - procedures, at a determined need to remove accumulated ash from said particulate filter 265, to indicate said need to the operator of said engine 231 .

The program P may be stored in an executable manner, or in a compressed manner, in a memory 560 and/or a read/write memory 550.

A statement that the data processing unit 510 performs a certain function means that the data processing unit 510 performs a certain part of the program stored in the memory 560, or a certain part of the program stored in the read/write memory 550.

The data processing unit 510 may communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended for communication with the data processing unit 510 via a data bus 51 1 . The read/write memory 550 is arranged for communication with the data processing unit 510 via a data bus 514. The links, e.g., L210, L220, L231 , LL233, L237, L277 may be connected to the data port 599 (see Figure 2).

When data is received in the data port 599, it is temporarily stored in the second memory part 540. When input data received is temporarily stored, the data processing unit 510 is ready to carry out execution of code in the manner described above.

Parts of the methods described herein may be carried out by the unit 500 with the help of the data processing unit 510, which runs the program stored in the memory 560 or the read/write memory 550. When the unit 500 runs the program, the procedures described herein are executed.

The foregoing description of the preferred embodiments of the present invention has been furnished for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the invention to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order to best explicate the principles of the invention and its practical applications, and to thereby enable one skilled in the art to understand the invention in terms of its various embodiments and with the various modifications that are applicable to its intended use.

Claims

1 . Method for determination of a cleaning need relating to a particulate filter (265) in the exhaust treatment system of an engine (231 ), from the point of view of ash occurrence, comprising the step to:

- determine a measure of accumulated ash occurrence in said particulate filter (265),

characterised by the step to:

- determine (s301 ; s340) said measure, based on the determined heat capacity (C1 ; C2) of said particulate filter (265) in at least two different states, with respect to accumulated ash occurrence; further comprising the step to:

- determine (s310; s320) said values (C1 ; C2) of said heat capacity in connection with transient processes relating to the exhaust temperature upstream and/or downstream of said particulate filter (265); and/or

- determine (s310; s320) said values (C1 ; C2) of said heat capacity, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter (265) exceeds a predetermined value (THtemp).

2. Method according to claim 1 , comprising the step to:

- determine (s310) a first value (C1 ) for said heat capacity of said particulate filter (265), based on a first state comprising determined parameter values relating to exhaust mass flow (MF1 ) from said engine (231 ), and a temperature difference (T1 -T2, T3-T2) relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter (265), and an expected low ash occurrence;

- determine (s320) a second value (C2) for said heat capacity of said particulate filter (265), based on a determination of said first value (C1 ) for said heat capacity, and on a second state, comprising determined parameter values relating to exhaust mass flow (MF2) from said engine (231 ), and a temperature difference (T1 -T2, T3-T2) relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter (265), and an expected higher occurrence in relation to said first state; and

- determine (s330, s340) said measure, based on a comparison between the thus determined two values (C1 , C2) for said heat capacity.

3. Method according to any of the previous claims, comprising the step to:

- regenerate said particulate filter (265) relating to soot particles, before said measure relating to accumulated ash occurrence is determined.

4. Method according to any of the previous claims, comprising the step to:

- predict a need to remove ash from said particulate filter (265), based on a determination of the development of said measure over time.

5. Method according to any of the previous claims, comprising the step to: - determine the need (s340) to remove accumulated ash from said particulate filter (265) at a predetermined value reached with respect to said measure; and

- at a determined need to remove accumulated ash from said particulate filter, indicate (s350) said need to the operator of said engine (231 ).

6. System for determination of a cleaning need relating to a particulate filter (265) in the exhaust treatment system of an engine (231 ), from the point of view of ash occurrence, comprising:

- elements (200; 210; 500) adapted to determine a measure of accumulated ash occurrence in said particulate filter (265),

characterised by:

- elements (200; 210; 500) adapted to determine said measure based on the determined heat capacity (C1 ; C2) of said particulate filter (265) in at least two different states, with respect to accumulated ash occurrence

- elements (200; 210; 500) adapted to determine said values (C1 ; C2) of said heat capacity in connection with transient processes relating to the exhaust temperature upstream and/or downstream of said particulate filter (265); and/or

- elements (200; 210; 500) adapted to determine said values (C1 ; C2) of said heat capacity, when a determined absolute temperature difference relating to the exhaust temperature upstream and downstream, respectively, of said particulate filter (265) exceeds a predetermined value (THtemp).

7. System according to claim 6, comprising:

- elements (200; 210; 500) adapted to determine a first value (C1 ) for said heat capacity of said particulate filter (265), based on a first state comprising determined parameter values relating to exhaust mass flow (MF1 ) from said engine (231 ), and a temperature difference (T1 -T2; T3-T2) relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter (231 ), and an expected low ash occurrence;

- elements (200; 210; 500) adapted to determine a second value (C2) for said heat capacity of said particulate filter (265), based on a determination of said first value (C1 ) for said heat capacity and on a second state comprising determined parameter values relating to exhaust mass flow (MF2) from said engine (231 ), and a temperature difference (T1 -T2; T3-T2) relating to the exhaust gas temperature upstream and downstream, respectively, of said particulate filter (265), and an expected higher ash occurrence in relation to said first state; and

- elements (200; 210; 500) adapted to determine said measure, based on a comparison between the thus determined two values (C1 , C2) for said heat capacity.

8. System according to claim 6 or 7, comprising:

- elements (200; 210; 500; 260) adapted to regenerate said particulate filter (265) with respect to soot particles, before said measure relating to accumulated ash occurrence is determined.

9. System according to any of claims 6-8, comprising:

- elements (200; 210; 500) adapted to predict a need to remove ash from said particulate filter (265), based on a determination of the development of said measure over time.

10. System according to any of claims 6-9, comprising:

- elements (200; 210; 500) adapted to determine the need to remove accumulated ash from said particulate filter (265) at a predetermined value reached with respect to said measure; and

- elements (200; 210; 500; 220) adapted, at a determined need to remove accumulated ash from said particulate filter (265), to indicate said need to the operator of said engine.

1 1 . Motor vehicle (100; 1 10) comprising a system according to any of claims 6-10.

12. Motor vehicle (100; 1 10) according to claim 1 1 , wherein the motor vehicle is one of a truck, a bus or a car.

13. Computer program (P) regarding an exhaust treatment system, wherein said computer program (P) comprises program code to cause an electronic control device (200; 500), or a computer (210; 500) connected to the electronic control device (200; 500) to perform the steps according to any of claims 1 -5.

14. Computer program product, comprising program code stored in a computer-readable medium, in order to perform the method steps according to any of claims 1 -5, when said program code is executed in an electronic control device (200; 500) or in a computer (210; 500) connected to the electronic control device (200; 500).