SE533724C2 - System and method for detecting clogging in an exhaust pipe - Google Patents

Description

25 30 35 533 724 required temperature increase. In such an exhaust after-treatment system, the injected fuel can cause a clogging of the filter if the fuel injection takes place in unsuitable operating conditions. In an SCR catalyst, nitric oxide (NOX) reacts with ammonia and is reduced to nitrogen gas. In this case, nitric oxide is the harmful ingredient that is intended to be removed from the exhaust gases and ammonia is the reducing agent used to accomplish this. Ammonia or urea (which is converted to ammonia) is injected into the exhaust gases upstream of the SCR catalyst. The reducing agent is usually a urea solution, for example the type of urea solution sold under the name AdBlue®. If urea solution in the form of, for example, AdBlue® is injected under unfavorable operating conditions, crystals can form from this urea solution and get stuck in the exhaust line or catalyst. These crystals can clog and damage the exhaust pipe or catalyst, which can cause costly repairs and downtime.

It is previously known to detect clogging of an exhaust after-treatment device by determining the pressure drop across the exhaust after-treatment device and comparing this pressure drop with a given limit value, as described, for example, in WO 2007/107873 A2. The pressure drop across the exhaust after-treatment device is determined by measuring the difference between the pressure in the exhaust line upstream of the exhaust after-treatment device and the pressure in the exhaust line downstream of the exhaust after-treatment device.

OBJECT OF THE INVENTION The object of the present invention is to provide a new and advantageous way of detecting clogging in an exhaust line from an internal combustion engine downstream of a turbine wheel which is arranged to drive a compressor wheel arranged in an air intake line to the internal combustion engine. SUMMARY OF THE INVENTION According to the present invention, said object is achieved by means of a system having the features defined in claim 1 and a method having the features defined in claim 6.

According to the invention, by means of a calculation model, a first charge pressure value representing a calculated charge pressure of the internal combustion engine is determined and, based on measured values from a pressure sensor which measures the air pressure in the internal combustion engine air intake line downstream of the compressor wheel, a value charge pressure of the internal combustion engine. Clogging in the exhaust line is then detected on the basis of a comparison between the first boost pressure value and the second boost pressure value.

A clogging in the exhaust line downstream of the turbine wheel can, for example, consist of a clogging of the exhaust line itself or a clogging of an exhaust after-treatment device arranged therein, for example in the form of a particle filter or a catalyst.

The invention is based on the fact that the flow rate of the exhaust gases in an exhaust line decreases with a clogging of the exhaust line or an exhaust after-treatment device arranged therein. The reduced flow rate of the exhaust gases leads to a reduced rotational speed of the turbine unit's turbine wheel, which in turn leads to a reduced rotational speed of the turbocharger compressor wheel and thereby a reduced boost pressure. By comparing the prevailing charge pressure measured in the internal combustion engine's air intake line downstream of the compressor wheel with an expected charge pressure, calculated using a calculation model based on prevailing operating conditions, it thus becomes possible to detect a clogging of the exhaust line or an arrangement therein. 10 15 20 25 30 35 533 724 The environment in an exhaust line from an internal combustion engine is aggressive with sharp temperature fluctuations, high temperatures and polluting substances, which places great demands on any sensors that must be installed in such an exhaust line and means that such donors become expensive and risk suffering from malfunctions. With the solution according to the invention, it becomes possible to determine the clogging of an exhaust line or an exhaust after-treatment device arranged therein without having to install a pressure sensor in the exhaust line, which thus entails an advantage with regard to costs and operational reliability.

The charge pressure is usually one of the parameters used as the value of an electronic engine control unit of a motor vehicle, the charge pressure being measured by means of a pressure sensor arranged in the air intake line of the internal combustion engine. The solution according to the invention can thus be implemented with the aid of the pressure sensor already previously available in the internal intake line of the internal combustion engine of a motor vehicle and requires only a relatively simple reprogramming of the electronic motor control unit or any other electronic data processing device of the motor vehicle. The invention can thus be implemented in a simple manner and at low cost.

According to an embodiment of the invention, a difference value is determined which represents the difference between said boost pressure values, this difference value being compared with a given limit value for detecting clogging in the exhaust line. This makes it possible in a simple manner to detect when the clogging of the exhaust line or an exhaust after-treatment device arranged therein has reached a predetermined level.

Other advantageous features of the system and method according to the invention appear from the dependent claims and the following description. The invention also relates to a computer program product having the features defined in claim 11 and an electronic control unit having the features defined in claim 13.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below with the aid of exemplary embodiments, with reference to the accompanying drawings.

It is shown in: Fig. 1 a schematic diagram of an internal combustion engine of a motor vehicle with an exhaust aftertreatment device in the form of an SCR catalyst arranged in an exhaust line from the internal combustion engine, Fig. 2 a schematic diagram of an internal combustion engine of a motor vehicle with an exhaust aftertreatment device in the form of a particle filter arranged in an exhaust line from the internal combustion engine, Fig. 3 is a principle sketch of an electronic control unit for implementing a method according to the invention, and Fig. 4 is a flow diagram illustrating a method according to an embodiment of the invention.

EMBODIMENTS OF THE INVENTION In Figs. 1 and 2, an internal combustion engine 1 and a turbocharger 2 of a motor vehicle 3 are schematically illustrated. a turbine wheel 6a arranged in the exhaust line 5 to be driven in rotation of the exhaust gas flow from the internal combustion engine 1. The turbocharger 2 further comprises a compressor 7 with a compressor wheel 7a arranged in the air intake line 4 to compress the air supplied to the combustion - 10 15 20 25 30 35 533 724 engine and thereby build up the desired boost pressure. The compressor wheel 7a and the turbine wheel 6a are operatively connected to each other, for example by being placed on one and the same shaft 8, so that the compressor wheel 7a is driven in rotation by the turbine wheel 6a. A pressure sensor 9 is arranged in the air intake line 4 downstream of the compressor wheel 7a for measuring the pressure in the air intake line of the internal combustion engine downstream of the compressor wheel, ie the boost pressure. In the example illustrated in Fig. 1, an exhaust after-treatment device 10 in the form of an SCR (Selective Catalytic Reduction) catalyst is arranged in the exhaust line 5 downstream of the turbine wheel 6a to effect catalytic conversion of environmentally hazardous constituents in the exhaust gases. to less environmentally hazardous substances. In this case, reducing agent is injected by means of an injector 11 into the exhaust gases in the exhaust line 5 at a location between the turbine wheel 6a and the catalyst 10, i.e. downstream of the turbine wheel and upstream of the catalyst. The injection device 11 comprises one or more injection means 12 arranged in the exhaust line 5 in the form of injection nozzles or the like, and a storage container 13 for reducing agents connected thereto. The injector 11 also comprises a control means 14, for example in the form of a control valve, which is arranged to control the supply of reducing agent to said one or more injectors 12, and a control means 15 connected to the control means 14. The control means 14 is controlled of said control means 15, which determines the amount of reducing agent to be injected into the exhaust gases based on the prevailing operating conditions of the internal combustion engine 1 and the catalyst 10. The reducing agent may be a urea solution, for example the type of urea solution sold under the name AdBlue®. AdBlue® is a solution consisting of 32.5% urea and 67.5% deionized water.

In the example illustrated in Fig. 2, an exhaust aftertreatment device 10 'in the form of a particulate filter is arranged in the exhaust line 5 downstream of the turbine wheel 6a for capturing particulate constituents of the exhaust gases. The exhaust line 5 illustrated in Fig. 1 could, of course, comprise one or more additional exhaust after-treatment devices arranged in series with the illustrated SRC catalyst 10. Similarly, the exhaust gas illustrated in Fig. 2 the line 5 may of course comprise one or more additional exhaust aftertreatment devices arranged in series with the illustrated particle filter 10 ”. Clogging in the exhaust line downstream of the turbine wheel 6a is detected by means of a system 20 comprising an electronic data processing device 21, which is connected to the above-mentioned pressure sensor 9 for receiving measured values from it with respect to the charge pressure of the internal combustion engine. The data processing device 21 is arranged to determine by means of a calculation model a first charge pressure value Vp1 which represents a calculated charge pressure of the internal combustion engine 1. The data processing device 21 is also arranged to determine, based on measured values from the pressure sensor 9, a second charge pressure value Vpg of the internal combustion engine 1. The data processing device 21 then performs a comparison between the first boost pressure value Vpj and the second boost pressure value Vpg and detects any clogging of the exhaust line 5 or an exhaust aftertreatment device 10, 10 'arranged therein based on the result of this comparison. Based on the correspondence, such as for example the difference, ratio or correlation, between said charge pressure values Vp1, Vpz, it is possible to determine the degree of clogging of the exhaust line or exhaust after-treatment device and / or whether the exhaust line or exhaust after-treatment device has become clogged to such an extent that measures need to be taken to restore the exhaust line or exhaust after-treatment device, ie to remedy the clogging.

The data processing device 21 is advantageously arranged to compare said charge pressure values Vp1, Vpz with each other by determining a difference value Vdiff representing the difference 103 between them, and then comparing this difference value Vdiff with a given limit value VG for detecting clogging. of the exhaust line 5 or the exhaust aftertreatment device 10, 10 '. In this case, the limit value VG is suitably chosen so that it corresponds to a condition when the exhaust line or exhaust after-treatment device has become clogged to such an extent that measures need to be taken to restore it. According to an alternative, the data processing device 21 is arranged to detect that the exhaust line 5 or the exhaust after-treatment device 10, 10 'is clogged when the data processing device determines that the difference value Vdm is greater than or equal to the limit value VG. According to another alternative, the data processing device 21 is arranged to detect that the exhaust line 5 or the exhaust after-treatment device 10, 10 'is clogged when the data processing device determines that the difference value Vdiff has been greater than or equal to the limit value VG for a given time. The data processing device 21 is suitably arranged to filter the difference value Vdiff in a suitable manner before the difference value is compared with the limit value VG.

The calculation model can be designed in any desired way and use any desired input parameters as long as it with a desired accuracy gives a correct value of the expected charging pressure under prevailing operating conditions. The calculation model is preferably designed to generate a charge pressure value Vp1 which represents the expected pressure in the air intake line 4 at prevailing operating conditions and with an exhaust line and exhaust after-treatment device which is not clogged.

The calculation model is suitably designed to use the following parameters as inputs: - the speed of the internal combustion engine 1, - the ambient air pressure, - the intake temperature, ie the temperature of the air in the air intake line 4 of the internal combustion engine, and - the load of the internal combustion engine. The data processing device 21 may be arranged to receive values relating to the engine speed, the ambient pressure and the suction temperature directly from sensors which are arranged to sense the magnitude of the respective parameters or from one or more electronic control units which are connected to such. sensors, such as for example from an electronic engine control unit 16 which is arranged to control the fuel injection of the internal combustion engine 1.

Said sensor comprises a speed sensor 17 for sensing the engine speed, a pressure sensor 18 for sensing the ambient pressure and a temperature sensor 19 for sensing the intake temperature. information about the prevailing load of the internal combustion engine 1 is available in the engine control unit 16 and the data processing device 21 is suitably connected thereto for receiving values regarding the size of the engine load.

The first boost pressure value Vp1 and the second boost pressure value Vpg can advantageously be calibrated against each other at times when the internal combustion engine 1 is in operation and the exhaust line 5 and / or the exhaust aftertreatment device 10, 10 'has just been reset, ie freed from clogging. The calibration takes place, for example, by adapting the calculation model and / or the pressure sensor 9 so that the calculated first charge pressure value VM will correspond to the measured second charge pressure value Vpg on these occasions. This enables an adjustment of the system during its operation.

A detected clogging could be used as a signal to automatically trigger a reset of a clogged exhaust line or exhaust aftertreatment device or be signaled to the driver of the vehicle so that he can initiate action for this.

The data processing device 21 may consist of a single electronic control unit of the vehicle 3, as illustrated in Figs. 1 and 2, or of two or more mutually cooperating electronic control units. Fig. 4 shows a flow chart illustrating an embodiment of a method according to the present invention for detecting clogging in an exhaust line 5 from an internal combustion engine 1 downstream of a turbine wheel 6a which is arranged to drive one in an air intake line. 4 compressor wheel 7a arranged for the internal combustion engine. In a first step S1, by means of a calculation model, a first boost pressure value Vpj is determined which represents a calculated boost pressure of the internal combustion engine 1 under prevailing operating conditions. In a second step S2, based on measured values from a pressure sensor 9 which measures the air pressure in the air intake line 4 of the internal combustion engine downstream of the compressor wheel 7a, a second charge pressure value Vpz representing a measured charge pressure of the internal combustion engine 1 is determined. the second boost pressure value Vpz to generate information regarding possible clogging in the exhaust line. Steps S1-S3 are then repeated after a certain time.

Computer program code for implementing a method according to the invention is suitably included in a computer program which can be read into the internal memory of a computer, such as the internal memory of an electronic control unit of a motor vehicle provided with an internal combustion engine and a turbocharger. Such a computer program is suitably provided via a computer program product comprising a data storage medium which can be read by an electronic control unit, which data storage medium has the computer program stored thereon. Said data storage medium is, for example, an optical data storage medium in the form of a CD-ROM, a DVD disc, etc., a magnetic data storage medium in the form of a hard disk, a floppy disk, a cassette tape, etc., or a flash memory or a memory of type ROM, PROM, EPROM or EEPROM.

A computer program product according to an embodiment of the invention comprises computer program code for in a motor vehicle, which is provided with an internal combustion engine and a turbine wheel arranged in an exhaust line from the internal combustion engine which is arranged to drive a comb arranged in an air intake line to the internal combustion engine. Bring an electronic data processing device to the vehicle: - to determine by means of a calculation model a first charge pressure value VP, which represents a calculated charge pressure of the internal combustion engine, - that, based on measured values from a pressure sensor which is arranged measuring the air pressure in the air intake line of the internal combustion engine downstream of the compressor wheel, determining a second charge pressure value Vpz representing a measured charge pressure of the internal combustion engine, and - detecting clogging in said exhaust line based on a comparison between the first charge value and the charge value Vpg.

Fig. 3 very schematically illustrates an electronic control unit 30 comprising an execution means 31, such as a central processing unit (CPU), for executing computer software. The execution means 31 communicates with a memory 33, for example of the RAM type, via a data bus 32. The control unit 30 also comprises data storage medium 34, for example in the form of a Flash memory or a memory of the type ROM, PROM, EPROM or EEPROM.

The execution means 31 communicates with the data storage medium 34 via the data bus 32. A computer program comprising computer program code for implementing a method according to the invention, for example in accordance with the embodiment illustrated in Fig. 4, is stored on the data storage medium 34.

The invention is of course not in any way limited to the embodiments described above, but a number of possibilities for modifications thereof should be obvious to a person skilled in the art, without this deviating from the basic idea of the invention as defined in the appended claims. .

Claims (13)

A system according to claim 1,. A system according to claim 2,. System according to claim 2, 533 724 12 PATENT CLAIMS 4. A system for detecting clogging in an exhaust line from an internal combustion engine downstream of a turbine wheel arranged to drive a compressor wheel arranged in an air intake line to the internal combustion engine, characterized in: - that the system (20) comprises an electronic data processing device ( 21) which is arranged to determine by means of a calculation model a first charge pressure value (Vp1) which represents a calculated charge pressure of the internal combustion engine and, based on measured values from a pressure sensor arranged to measure the air pressure in the internal combustion engine air intake line of the internal combustion engine , determining a second charge pressure value (Vpz) representing a measured charge pressure of the internal combustion engine, and - that the data processing device (21) is arranged on the basis of a comparison between the first charge pressure value (Vp1) and the second charge pressure value (Vpz). detect clogging in said exhaust line. characterized in that the data processing device (21) is arranged to determine a difference value (Vdiff) representing the difference between said charge pressure values (Vp1, Vpz), and to compare this difference value (Vdm) with a given limit value (VG) for detecting clogging. in said exhaust line. characterized in that the data processing device (21) is arranged to detect that said exhaust line or an exhaust after-treatment device arranged therein is clogged when the data processing device determines that the difference value (Vdiff) is greater than or equal to the limit value (VG). characterized in that the data processing device (21) is arranged to detect that said exhaust line or an exhaust aftertreating device arranged therein is clogged when the data processing device determines that the difference value (Vdm) has been greater than a given length of time. or equal to the limit value (VG). . System according to one of Claims 1 to 4, characterized in that the data processing device (21) is arranged to calculate the first boost pressure value (Vp1) on the basis of at least the following parameters: - the speed of the internal combustion engine, - the ambient air pressure, - the temperature of the air in the internal combustion engine and - the load of the internal combustion engine. . Method for detecting clogging in an exhaust line (5) from an internal combustion engine (1) downstream of a turbine wheel (6a) which is arranged to drive a compressor wheel (7a) arranged in an air intake line (4) to the internal combustion engine, characterized therefrom: - that a first charge pressure value (Vpj) representing a calculated charge pressure of the internal combustion engine (1) is determined by means of a calculation model, - that a second charge pressure value (Vpz) representing a measured charge pressure of the internal combustion engine (1) is determined based on measured values from a pressure sensor (9) which measures the air pressure in the air intake line (4) of the internal combustion engine downstream of the compressor wheel (7a), and - clogging in said exhaust line (5) is detected based on a comparison between the first charge pressure value (VM) and the second boost pressure value (Vpz). . Method according to claim 6, characterized in that a difference value (Vdm) representing the difference between said charge pressure values (Vp1, Vpz) is determined and compared with a given limit value (VG) for detecting clogging in said exhaust line. 10 15 20 25 30 35 533 724 14 Method according to claim 7, characterized in that it is detected that said exhaust line (5) or an exhaust after-treatment device (10; 10 ') arranged therein is clogged when it is determined that the difference value (Vdm) is greater than or equal to the limit value (VG). . Method according to claim 7, characterized in that it is detected that said exhaust line (5) or an exhaust after-treatment device (10; 10 ') arranged therein is clogged when it is determined that the difference value (Vdm) for a given length of time been greater than or equal to the limit value (VG). Method according to one of Claims 6 to 9, characterized in that the first boost pressure value (VN) is calculated on the basis of at least the following parameters: - the speed of the internal combustion engine (1), - the ambient air pressure, - the temperature of the air in the internal combustion engine air line 4 ), and - the load of the internal combustion engine. A computer program product comprising computer program code for, in a motor vehicle provided with an internal combustion engine and a turbine wheel arranged in an exhaust line from the internal combustion engine arranged to drive a compressor wheel arranged in an air intake line to the internal combustion engine, bringing an electronic data processing device: using a calculation model to determine a first charge pressure value (Vpi) representing a calculated charge pressure of the internal combustion engine, - to, based on measured values from a pressure sensor arranged to measure the air pressure in the internal combustion engine air intake line downstream ) representing a measured charge pressure of the internal combustion engine, and 533 724 - detecting clogging in said exhaust line based on a comparison between the first charge pressure value (Vp1) and the second charge pressure value (Vpz). 5 Computer program product according to claim 11, characterized in that the computer program product comprises a data storage medium which can be read by an electronic control unit, said computer program code being stored on the data storage medium. 10 An electronic control unit of a motor vehicle comprising an execution means (31), a memory (33) connected to the execution means and a data storage medium (34) connected to the execution means, the computer program code of a computer program product according to claim 11 being stored on said data storage means. Ring medium (34).