SE1450082A1 - A system and method for determining the presence of fuel in an exhaust gas purification system - Google Patents

Abstract

The invention relates to a method for determining the presence of fuel in exhaust gases from an internal combustion engine (231) with an exhaust gas purification system comprising at least one NO sensor (221; 222) arranged downstream of said internal combustion engine (231), comprising the steps of: - determining (s410) a NO content of exhaust gases from said internal combustion engine (231); - following signaling (s410) from said NO sensor (221; 222); and - take (s440) changes in the signal emitted by the NO sensor (221; 222) (S1; S2) regarding NO content in the exhaust gases and / or error message signaling regarding lack of measuring function of said NO sensor (221; 222) as an indication of fuel presence in the exhaust gases from said internal combustion engine (231). The invention also relates to a computer program product comprising program code (P) for a computer (200; 210) for implementing a method according to the invention. The invention also relates to systems for determining the presence of fuel and a motor vehicle (100) equipped with said system. Figure 2b for publication

Description

TECHNICAL FIELD The present invention relates to a method for determining the occurrence of fuel in an exhaust gas purification system. The invention also relates to a computer program product comprising program code for a computer for implementing a method according to the invention. The invention also relates to a system for determining the occurrence of fuel in an exhaust gas cleaning system and a motor vehicle which is equipped with said system.

BACKGROUND Exhaust gas cleaning systems of today's motor vehicles include a number of different components.

For example, an exhaust gas purification system may include a DOC unit (Diesel Oxidation Catalyst) arranged in a passage downstream of an internal combustion engine has the vehicle. Other components that may be arranged downstream of said engine are a DPF unit (Diesel Particulate Filter) and a SCR catalyst (Selective Catalytic Reduction). Said exhaust gas purification system may comprise an industry metering unit arranged to inject a fuel in a controlled manner into an exhaust passage upstream of said DOC unit in order to bring about adverse temperature rises when the engine exhaust gases. In this case, a radiating temperature can be controlled by one or more of said components.

For many reasons, it is inconvenient to be able to diagnose individual components of exhaust gas cleaning systems, such as trucks and buses. Diagnosis of components has exhaust gas purification systems has motor vehicles can, for example, be difficult to determine radiating performance and / or function has the various components. Diagnosis of individual components in exhaust gas cleaning systems can in some states be subject to laws, regulations or directives, which of course vehicle manufacturers must adhere to, not least from an environmental and competition perspective. 2 Diagnosis of an internal combustion engine and / or the said industry dosing unit has the engine after-treatment system is today problematic for several reasons. Diagnostic tools are generally time consuming and costly to develop.

Today, it is black to detect paint, and in particular a small paint, from the said internal combustion engine and / or the said industry dosing unit.

According to some known procedures for determining the fuel occurrence of exhaust gases from an internal combustion engine, ocular manual inspection and / or detection by means of external food equipment is required, which is both time consuming and costly.

US 20100319316 describes a system and a method for diagnosing an oxidation catalyst.

JP 2012036856 describes a device for diagnosing a catalyst.

SUMMARY OF THE INVENTION Thus, there is a need to reliably diagnose components of a motor vehicle to detect industry leakage.

There is a need to diagnose an internal combustion engine in an efficient, reliable and user-friendly manner and / or an industry dosing unit has, for example, a vehicle.

An object of the present invention is to provide a new and advantageous process in an exhaust gas purification system.

An object of the present invention is to provide a new and advantageous method for determining the occurrence of fuel in exhaust gases from an internal combustion engine.

Another object of the invention is to provide a new and advantageous system in an exhaust gas purification system and a new and advantageous computer program in an exhaust gas purification system. Another object of the invention is to provide a new and advantageous system for determining fuel occurrence in exhaust gases from an internal combustion engine and a new and advantageous computer program for determining fuel occurrence in exhaust gases from an internal combustion engine.

A further object of the invention is to provide an alternative method of an exhaust gas purification system, an alternative system of an exhaust gas purification system and an alternative computer program of an exhaust gas purification system.

A further object of the invention is to provide a method, a system and a computer program for achieving a reliable diagnosis of an internal combustion engine having a vehicle.

A further object of the invention is to provide a method, a system and a computer program for achieving a reliable diagnosis of an industry dosing unit having an after-treatment system having an internal combustion engine.

Some of said objects are achieved with a method for determining the fuel presence in exhaust gases from an internal combustion engine according to claim 1. Other objects are achieved with a system for determining the fuel presence in exhaust gases from an internal combustion engine according to claim 5. Advantageous embodiments are stated in the dependent claims.

According to one aspect of the present invention, there is provided a method of determining the presence of fuel in exhaust gases from an internal combustion engine with an exhaust gas purification system comprising at least one NO 2 sensor arranged downstream of said internal combustion engine. The method comprises the steps of: - determining an NO, - content of exhaust gases from said internal combustion engine; - follow signaling from the said NO, sensor; and - take changes has the NO, sensor's emitted signal regarding NO, - content in the exhaust gases and / or error message signaling regarding lack of food function has the said NO, sensor as an indication of industry occurrence in the exhaust Iran said combustion engine. The said fuel occurrence has the said exhaust gases can be caused by the fuel leakage has the said internal combustion engine. Said fuel occurrence has said exhaust gases can be caused by fuel leakage from an industry metering unit has said exhaust gas purification system. Said fuel occurrence of said exhaust gases can be caused by both fuel leakage has the said internal combustion engine as fuel leakage from the said fuel metering unit.

In this case, a reliable procedure is provided for diagnosing an internal combustion engine with an exhaust gas purification system, for example in a motor vehicle.

This provides a reliable method for diagnosing an industry dosing unit having a post-treatment system of said internal combustion engine, for example having a motor vehicle.

By utilizing a potential for fuel, for example diesel, has at least one NOR sensor having said exhaust gas cleaning system, a reliable and robust method for diagnosing an internal combustion engine and / or an industry dosing unit has a finishing system for said engine 20 can be provided.

According to an exemplary embodiment, it can then be determined whether at least any of the following phenomena occur: - lowering of the level has continuously detected NOR content of said at least one NOR sensor; increase in level has continuously detected NOR content of only one NOR sensor arranged downstream of a DOC unit; high frequency oscillation has detected NOR content of said at least one NOR sensor; and - error signaling has said at least one NOR sensor.

A measure of radiating performance has said internal combustion engine and / or industry metering unit, including any degradation of normal or satisfactory performance, can be determined on the basis of: - a relative measure of said decrease in level of continuously detected NOR content of said at least one NOR sensor ; and / or - a magnitude for said changes in the NOR sensor's emitted signal for NOR content, for example high frequency oscillation; and / or - a magnitude mat for high frequency oscillation of detected NOR content of said at least one NOR sensor; and / or - intensity and / or frequency and / or information content in said error signaling of said at least one NOR sensor.

The said NOR content of the exhaust gases in the said combustion engine Iran can be determined continuously and / or intermittently.

The procedure may comprise the step of: - following changes in the said NOR content, whereby changes in the form of a decrease in the determined NOR content and / or high-frequency oscillation in the said NOR content are taken as an indication of the occurrence of fuel in the said exhaust gases. In this case, an automatic, robust and reliable way of determining industry occurrence can be provided.

The process may comprise the step of: - continuously determining the NOR content of said exhaust gases upstream of existing units of said exhaust gas purification system. In this case, any fuel leakage can be determined in an accurate manner because fuel from the engine and / or fuel metering unit is not stored / burned / affected to a greater extent by components of said exhaust gas purification system.

The process may comprise the step of: - continuously determining the NOR content of said exhaust gases downstream of an SCR catalyst of said exhaust gas purification system.

The method may comprise the step of: - continuously determining the NOR content in said exhaust gases downstream of a DOC unit of said exhaust gas purification system. In this case, it can be determined whether or not an increase in detected NOR content occurs at a position downstream of said DOC unit. The method may comprise the step of: - following changes having a first NO 'content and a second NO' content, which are determined at two respective different positions of said exhaust gas purification system, changes in the form of a decrease in the determined NO. content and / or high-frequency oscillation has the said first NO, content and / or the said second NO, content taken as an indication of the occurrence of fuel in the said exhaust gases.

The procedure may comprise the step of: - following changes has the said first NO, content during a period of suspended fuel supply has the said industry dosing unit, whereby changes in the form of a reduction of the fixed NO content are taken as an indication of fuel occurrence in said exhaust gases.

The procedure may comprise the step of: - following changes has a NO, -content downstream of said DOC unit during a period of suspended fuel supply has said industrial dosage unit, whereby changes in the form of an increase of fixed NO.-content are taken as an indication of industry occurrence in said exhaust.

The procedure may comprise the step of: - following changes has the said first NO, -content during a period of suspended fuel supply has the said industry dosing unit, wherein changes in the form of a decrease in fixed NO, -content and high frequency oscillation have the said NO, -content are taken as indication of industry occurrence in the said exhaust gases.

The method may comprise the step of: - following changes having a NO content downstream of said DOC unit during a period of suspended fuel supply having said industry metering unit, changes in the form of an increase in fixed NO content and high frequency oscillation having said NO, - content is taken as an indication of the occurrence of fuel in the said exhaust gases.

The method may comprise the step of: - following changes in said first NO, content and / or said second NO, content during a period of suspended supply of fuel has said industry dosage unit, 7 wherein changes in the form of a reduction of fixed NO, content and / or high-frequency oscillation has said first NOx content and / or said second NOx content is taken as an indication of fuel occurrence in said exhaust gases.

The method may comprise the step of: - following changes has said first NOx content and / or said second NOx content during a period of suspended fuel supply has said industry dosing unit, changes in the form of a decrease in fixed NOx content and / or high frequency oscillation has said first NOx content and / or an increase in said determined second NOx content is taken as an indication of fuel occurrence in said exhaust gases.

In this case, it can be advantageously established that fuel is actually present mixed with exhaust gases from said engine has said exhaust gas purification system.

The process may further comprise the step of: - comparing changes having said first NOx content and said second NOx content, a deficient function having said internal combustion engine and / or said fuel metering unit being concluded as fuel occurrence in said exhaust gases is found by similar changes having said first NOx content and said other NOx content.

Said similar changes may include a decrease in said first NOx content and said second NOx content, respectively. Said respective depressions may be temporary depressions relative to a measured NOx content where fuel is not supplied to the exhaust gases from said engine and / or fuel metering unit.

According to an exemplary embodiment, the method may comprise the step of: - comparing changes having said first NOx content and said second NOx content, a deficient function having said internal combustion engine and / or said fuel metering unit being concluded as the fuel occurrence in said exhaust gases is found of only said second NOx content is determined. Said similar changes may include high-frequency oscillation of said first NOR content and said second NOR content, respectively. The said high-frequency oscillation can alternatively be called a ripple.

The method may comprise the step of: - taking a malfunction of said internal combustion engine and / or fuel metering unit which is concluded in the presence of a signal regarding malfunction to 1610 of fuel occurrence in said exhaust gases in connection with the feeding of said first NOR content and / or the feeding of said second NOR- halt.

As the said at least one NOR sensor is exposed to industry, these can be temporarily, or permanently, negatively affected. In this case, a lack of food function can cause the sensors to arise. In order to inform a control unit of the exhaust gas purification system, the said NOR sensors are arranged to generate an error signal indicating that the sensor is negatively affected and therefore may not be reliable. According to an aspect of the inventive method, such signals can be used to detect the presence of fuel in said exhaust gases, and in this case fuel leakage also has said internal combustion engine and / or said fuel metering unit.

The process may comprise the step of: - ceasing to supply a reducing agent to said exhaust gases in order to improve the determination of a process having said second NOR content. According to one aspect of the present invention, there is provided a system for determining the occurrence of fuel in the exhaust gases of an internal combustion engine with an exhaust gas purification system comprising at least one NOR sensor arranged downstream of said internal combustion engine, comprising: at least one NOR sensor adapted to determine an NOR content of exhaust gases. from said combustion engine; means adapted to detect changes in signaling emitted from said NOR sensor regarding NOR content in the exhaust gases; and / or - means adapted to detect error message signaling regarding food malfunction has said NOR sensor; and 9 - means adapted to determine the presence of fuel in the exhaust gases from said internal combustion engine on the basis of said detected changes in said signaling emitted from said NO 2 sensor regarding NOx content in the exhaust gases and said detected error message signaling, respectively.

The system may comprise: - means adapted to monitor changes in said NOx content; means arranged to take changes in the form of a decrease in the determined NOx content and / or high-frequency oscillation of the said NO, - content as an indication of the presence of fuel in the said exhaust gases.

The system may comprise: - means adapted to continuously determine NOx content in said exhaust gases upstream of existing units of said exhaust gas purification system.

The system may comprise: - means adapted to continuously determine NOx content in said exhaust gases downstream of said DOC unit of said exhaust gas purification system. The system may comprise: - means adapted to monitor changes in said NO 2 content downstream of said DOC unit; means arranged to take changes in the form of an increase in fixed NO, - content downstream of said DOC unit and / or high-frequency oscillation of said NOR content as an indication of fuel occurrence in said exhaust gases.

The system may comprise: means adapted to continuously determine NOx content in said exhaust gases downstream of an SCR catalyst of said exhaust gas purification system.

The system may comprise: 30 means adapted to indicate the presence of fuel in the exhaust gases from the said internal combustion engine.

The system may comprise: - means adapted to vary the supply of reducing agent to said exhaust gases in order to improve the determination of a process having said second NOR content.

The system may comprise: - an industry dosing unit arranged upstream of existing units of said exhaust gas purification system; and - means adapted to take this as an indication of fuel leakage from said internal combustion engine and / or from said fuel metering unit in the event of a determined fuel hazard in the exhaust gases from said internal combustion engine.

Said industry dosing unit may be arranged upstream of said at least one NOR sensor.

According to one aspect of the present invention, there is provided a motor vehicle comprising the inventive system for determining fuel occurrence in exhaust gases from an internal combustion engine with an exhaust gas purification system.

The motor vehicle can be anything from a truck, bus or car.

According to one aspect of the present invention, there is provided a computer program for determining the fuel presence of exhaust gases from an internal combustion engine with an exhaust gas purification system comprising at least one NOR sensor arranged downstream of said internal combustion engine, said computer program comprising program code for causing an electronic controller or other computer connected thereto. electronic control unit to perform the steps according to any one of claims 1-4.

According to one aspect of the present invention, there is provided a computer program product comprising a program code stored on a computer readable medium for performing the method steps of any of claims 1-4, when said program code is crossed on an electronic control unit or another computer connected to the computer. electronic control unit.

According to one aspect of the present invention, there is provided a computer program in an exhaust gas purification system, said computer program comprising program code for causing an electronic control unit or another computer connected to the electronic control unit to perform the steps of any of claims 1-4.

According to one aspect of the present invention, computer programs are provided in an exhaust gas purification system, wherein said computer program includes program code for causing an electronic control unit or another computer connected to the electronic control unit to perform the steps of any of claims 1-4, when said program code is crossed. control unit or said computer.

According to one aspect of the present invention, computer programs are provided in an exhaust gas purification system, said computer program comprising program code stored on a computer readable medium for causing an electronic control unit or another computer connected to the electronic control unit to perform the steps of any of claims 1. -4.

According to one aspect of the present invention, there is provided a computer program product comprising a program code stored on a computer readable medium for performing the method steps of any of claims 1-4, when said computer program According to one aspect of the present invention, there is provided a computer program product comprising a program code non-volatile stored on a computer readable medium for performing the method steps of any of claims 1-4, when said computer program is crossed on an electronic control unit or another computer connected to the electronic control unit.

Additional objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details, as well as via description of the invention. While the invention is described below, it should be understood that the invention is not limited to the specific details described. Those skilled in the art having access to laroma hari will recognize further applications, modifications, and incorporations within other fields which are within the scope of the invention. SUMMARY DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and further objects and advantages thereof, reference is now made to the following detailed description which is to be read in conjunction with the accompanying drawings in which like reference numerals refer to like parts in the various figures, and in which: Figure 1 schematically illustrates a vehicle, according to an embodiment of the invention; Figure 2a schematically illustrates a subsystem of the vehicle shown in Figure 1, according to an embodiment of the invention; Figure 2b schematically illustrates a subsystem of the vehicle shown in Figure 1, according to an embodiment of the invention; Figure 3a schematically illustrates a diagram according to an embodiment of the invention; Figure 3b schematically illustrates a diagram, according to an embodiment of the invention; Figure 3c schematically illustrates a diagram, according to an embodiment of the invention; Figure 4a schematically illustrates a flow chart of a process, according to an embodiment of the invention; Figure 4b schematically illustrates in further detail a flow chart of a method, according to an embodiment of the invention; and Figure 5 schematically illustrates a computer, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE FIGURES Referring to Figure 1, a side view of a vehicle 100 is shown. The exemplary vehicle 100 consists of a tractor 110 and a trailer 112. The vehicle may be a heavy vehicle, such as a truck or a bus. The vehicle can alternatively be a car. In the terms "exhaust gas purification system" and "after-treatment system" are used synonymously. Said exhaust gas purification system or after-treatment system may at least partially comprise an SCR system. The term "lank" refers to a communication link which may be a physical line, such as an optoelectronic communication line, or a non-physical line, such as a wireless connection, for example a radio or microwave line.

Hari refers to the term "reductant" as a means used to react with certain emissions in an SCR system. These emissions can e.g. include NOR gas. Said reductant according to a procedure so-called AdBlue. Of course, other types of reductants can be used. Here, AdBlue is cited as an example of a reductant, but one skilled in the art will recognize that the inventive process and inventive system can be realized for other types of reductants, with the necessary modifications.

In this case, the term "fuel" refers to a hydrocarbon-based fuel, such as diesel, gasoline, vegetable or synthetic oil, ethanol or propane. Said industry may be in liquid or gaseous form.

It was pointed out that the invention is suitable for application to a suitable exhaust gas purification system, and is not limited to an exhaust gas purification system comprising an SCR system of motor vehicles. The inventive method and the inventive system make choices for other platforms which include an exhaust gas purification system of motor vehicles, such as e.g. watercraft. The watercraft can be of any kind, such as e.g. motor boats, ships, ferries or ships.

The inventive method and the inventive system according to an aspect of the invention are also suitable for e.g. tractors, dump trucks, power tools, industrial engines and / or motorized industrial robots.

The inventive method and the inventive system according to an aspect of the invention also illuminate choices for different types of power plants, such as e.g. an electric power plant comprising a diesel generator. The inventive method and the inventive system make choices for an arbitrary engine system that includes an engine, such as e.g. at a locomotive or other platform.

The inventive method and the inventive system make choices for a system which includes a NOR generator, for example a diesel engine, the exhaust gases of which are to be purified.

The inventive method and the inventive system make choices for a system that includes a NOR generator, such as a diesel engine.

In this he refers to the term "line" to a passage for holding and transporting a fluid, such as e.g. a reductant in liquid form. The pipe can be a rudder of any dimension. The cable can consist of an arbitrary, suitable material, such as e.g. plastic, rubber or metal.

Referring to Figure 2a, a subsystem 299 of the vehicle 100 is shown. The subsystem 299 may be located in the tractor 110. The subsystem 299 may form part of an SCR system incorporating the exhaust gas purification system in accordance with one aspect of the present invention. Said exhaust gas purification system is described in further detail with reference to Figure 2b.

According to this example, the subsystem 299 consists of a container 205 which is arranged to hold a reductant. A first line 271 is arranged to direct the reductant to a pump 230 Iran the container 205. The pump 230 is arranged to pump the reductant from the container 205 via the first line 271 and via a second line 272 supply said reductant to a dosing unit 250. The pump 230 is arranged to pressurize the reductant in the second line 272. The dosing unit 250 is arranged to supply said reductant to an exhaust gas purification system (see Figure 2b) of the vehicle 100. More specifically to the dosing unit 250 arranged to supply in a controlled manner a suitable amount of reductant to an exhaust purification system of the vehicle 100. According to this embodiment, an SCR catalyst (see Figure 2b) arranged downstream of a low supply of the reductant is provided. The amount of reductant supplied to the exhaust system is intended to be used in the SCR catalyst to reduce the amount of unwanted emissions.

A third conduit 273 is presently disposed between the metering unit 250 and the container 205. The third conduit 273 is arranged to return a certain amount of the reductant fed to the metering unit 250 to the container 205.

The first control unit 200 is arranged for communication with the pump 230 via a line 292. The first control unit 200 is arranged to control operation of the pump 230 in order to e.g. regulate the flow of the reductant within the subsystem 299.

The first control unit 200 is arranged for communication with the dosing unit 250 via a long L250. The first control unit 200 is arranged to control the operation of the dosing unit 250 in order to e.g. regulating the supply of the reductant to the exhaust gas purification system has the vehicle 100. The first control unit 200 is arranged to activate circulation of said reducing agent by means of said pump 230 as it is judged to be suitable. The first control unit 200 is arranged to activate dosing of said reducing agent when it is judged to be appropriate. The first control unit 200 is arranged to control the dosing of reducing agent by means of the dosing unit 250 in a variable manner. Thus, a mass flow per unit time can be varied steplessly in an appropriate manner.

According to one aspect of the present invention, said first control unit 200 is arranged to control said dosing unit 250 in such a manner that the supply of reducing agent to said exhaust gases temporarily ceases. Thus, in diagnosing an internal combustion engine and / or an industry metering unit (see Figure 2b), according to one aspect of the present invention, no or substantially no reducing agent is supplied to an SCR catalyst having the exhaust gas purification system supplied to one aspect of the present invention. This enables efficient diagnosis of the said internal combustion engine and / or industry metering unit has the said exhaust gas purification system.

A second control unit 210 is arranged for communication with the first control unit 200 via a long L210. The second control unit 210 may be releasably connected to the first control unit 200. The second control unit 210 may be a control unit external to the vehicle 100. The second control unit 210 may be arranged to perform the inventive process steps. The second control unit 210 can be used to upload program code to the first control unit 200, in particular program code to perform the inventive method. The second control unit 210 may alternatively be arranged for communication with the first control unit 200 via an internal network in the vehicle. The second control unit 210 may be arranged to perform substantially the same functions as the first control unit 200.

Figure 2b schematically illustrates a subsystem 289 of the vehicle 100 shown in Figure 1, according to an embodiment of the invention. Said subsystem 289 forms part of an exhaust gas purification system of the vehicle 100. Said subsystem 299 described with reference to Figure 2a may also form part of said exhaust gas purification system.

An engine 231 is provided, which in operation causes an exhaust gas flow which is led via a first passage 235 to a DOC unit 260. A second passage 245 is arranged to direct exhaust gases from said DOC unit 260 to a DPF unit 265. Said DPF unit 265 includes a diesel particulate filter. A third passage 255 is arranged to direct exhaust gases from said DPF unit 265 to an SCR catalyst arrangement 270. A fourth passage 256 is arranged to direct exhaust gases from said SCR catalyst arrangement 270 to an environment of the vehicle 100.

Said dosing unit 250 as described with reference to Figure 2a is arranged to dose reducing agent into said third passage 255. It was pointed out that said exhaust gas purification system does not necessarily include said SCR catalyst arrangement 270 and certain components of said subsystem 299, for example said dosing unit 250, the container 205 and the pump 230.

The first control unit 200 is arranged for communication with the motor 231 via a long L231. The first control unit 200 is arranged to control operation of said engine 231. For example, the first control unit 200 is arranged to control fuel metering to the combustion chamber of said engine 231. In this case, the first control unit 200 is arranged to control fuel metering in such a way that unburned fuel can be carried. said exhaust gases to the first passage 235. In this case, the first control unit 200 is arranged that during an appropriate period of time, when determination of fuel occurrence in exhaust gases from said engine 231 is to take place, control said fuel dosage in such a way that a lot of Mort unburned fuel in said exhaust gases are eliminated or minimized. In this case, for example, the so-called post-injections.

Fuel metering means 233 are arranged upstream of said DOC unit 260 and downstream of said motor 231. The first control unit 200 is arranged in communication with said fuel metering means 233 via a line L233. The first control unit 200 is arranged to control the dosing of fuel, for example diesel, into said first passage 235 by means of said industry dosing means 233.

Thus, fuel in a controlled manner, by means of said first control unit 200, can be supplied to said DOC unit 260 from said motor 231 and / or said fuel metering means 233. According to one aspect of the present invention, the first control unit 200 is arranged to control fuel metering on such provided that no fuel is actively supplied to the exhaust gases in said first passage 235 upon diagnosis of said engine 231 and / or fuel metering means 233.

By actively preventing unburned fuel from being supplied to exhaust gases in said first passage 235, it can be determined according to the invention whether the presence of fuel due to leakage from said engine 231 and / or said fuel metering means 233 is present.

A first NOR sensor 221 is arranged upstream of said DOC unit 260 at said first passage 235. Said first NOR sensor 221 is arranged for communication with the first control unit 200 via a long L221. Said first NOR sensor 221 is arranged to continuously determine a radiating NOR content in the first passage 235. Said first NOR sensor 221 is arranged to continuously send signals Si including information about a radiating NOR content in said first passage 235 to the first control unit 200 via line L221.

A second NOR sensor 222 is arranged downstream of said DOC unit 260 at said second passage 245. Said second NOR sensor 222 is arranged for communication with the first control unit 200 via a line L222. Said second NON sensor 222 is arranged to continuously determine a radiating NON content in the second passage 245. Said second NON sensor 222 is arranged to continuously send signals S2 comprising information am a radiating NON content in said second passage 245 to the first control unit 200 via the line L222.

Said first NON sensor 221 and said second NON sensor 222 can be used to provide information on the current NOR content in the first passage 235 and the second passage 245, respectively. In this case, the first control unit 200 can be arranged to control the supply of fuel in the first passage. first passage 235 in an appropriate manner on the basis of information thereon.

According to one embodiment, only the first NON sensor 221 is arranged on the system 289. In this case, the first NON sensor 221 can be arranged in a suitable place, for example in the first passage 235.

According to one embodiment, only the first NON sensor 221 is provided, which may be arranged downstream of the SCR catalyst arrangement 270 in the fourth passage 256.

According to the embodiment described with reference to the exhaust gas purification system illustrated in Figure 2b, said second NON sensor 222 is arranged in the second passage 245. It was pointed out that the second NON sensor 222 according to an alternative embodiment may be arranged in the third passage 255. , downstream of said DPF unit and upstream of said SCR catalyst arrangement 270. According to an alternative embodiment, the second NON sensor 222 may be arranged in the fourth passage 256, downstream of said SCR catalyst arrangement 270.

According to an embodiment, said first NON sensor 221 is arranged in the first passage 235, upstream of said DOC unit 260 and downstream of said motor 231 to continuously feed / detect / determine a first NON content has the exhaust gases there and said second NON sensor 222 arranged downstream of said DOC unit 260, for example has a flake of the passages 245, 255 or 256, in order to continuously feed / detect / determine a second NON content, the exhaust gases from the engine 231. 19 According to an exemplary embodiment, there may be tens NOR sensor 222 is provided with the exhaust gas purification system 289. In this case, the process of having said plurality of NOR sensors 222 can be considered according to the inventive method. For example, a decrease in NO 2 content and / or high frequency oscillating hash and NOR signal can be used to determine fuel occurrence of exhaust gases downstream of said combustion engine 231. For example, an increase in NOR content may only have said second NOR sensor 222, which is arranged downstream of said DOC unit 250, is used to determine the occurrence of fuel gases downstream of said combustion engine 231. A temperature sensor 241 is arranged upstream of said DOC unit 260 at said first passage 235. Said temperature sensor 241 is arranged for communication with the first control unit 200. via a long L241. Said temperature sensor 241 is arranged to continuously determine a radiating temperature Tlmeas has the exhaust gases in the first passage 235. Said temperature sensor 241 is arranged to continuously send signals ST1meas including information at a radiating temperature T1meas has the exhaust gases in said first passage 235 to the first control unit 200 lanken L241.

According to one embodiment, the first control unit 200 is arranged to determine by means of a calculating model stored therein a radiating temperature T1cal has the exhaust gases in the first passage 235. Said radiating temperature T1cal has the exhaust gases in the first passage 235 can be determined on the basis of e.g. a fixed exhaust mass flow and a matte on to the engine 230 dosed amount of fuel. Thus, the said radiating temperature T1cal can be calculated / modeled / estimated in a suitable manner by means of the said first control unit 200.

A sensor (not shown) for supplying a radiating exhaust mass flow MF may be provided in the first passage 235. Said exhaust mass flow sensor is arranged to continuously determine a radiating exhaust mass flow MF in the first passage 2 and send signals including the information thereon to the first passage 200. via a dedicated link (not shown).

According to one embodiment, the first control unit 200 is arranged to determine by means of a calculation model stored therein a radiating exhaust mass flow MF in the first passage 235. Said radiating exhaust mass flow MF in the first passage 235 can be determined on the basis of e.g. a determined operating state of the motor 231.

The first control unit 200 is arranged to continuously estimate a radiating temperature Tmod has DOC unit 260 by means of a stored model. The first control unit 200 is arranged to continuously estimate a radiating temperature Tmod has a named DOC unit 260 by means of a stored model. the control unit 200 is arranged to calculate by means of said calculation model a radiating temperature Tmod has the DOC unit 260 on the basis of said determined temperature has the exhaust gases Tlmeas and / or Ti cal in the first passage 235. According to an example the first control unit 200 is arranged to said model calculates a radiating temperature Tmod has the DOC unit 260 on the basis of a metered amount of fuel in the first passage 235, said fixed temperature Tlmeas and / or Ti cal has the exhaust gases in the first passage 235 and a radiating exhaust mass flow 15 MF in the first passage 235.

According to an exemplary embodiment, a temperature sensor is provided which is arranged to supply a radiating temperature having the DOC unit 260. In a corresponding manner as described above, the respective components of the respective components can be fed / detected / calculated / determined, for example said DPF unit 265 and said SCR catalyst arrangement 270.

The first control unit 200 is arranged to determine whether the respective component, i.e. for example DOC unit 260, DPF unit 265 and SCR catalyst arrangement 270, are active or not. The first control unit 200 may then be arranged to determine if a measured / detected / calculated / determined temperature has the respective component below a certain respective tooth temperature. The respective tooth temperature can also be called the activation temperature. According to one aspect of the present invention, the inventive method is performed when the first controller 200 determines that at least one component is not active. According to one aspect of the present invention, the inventive method is performed when the first controller 200 determines that not all components 260, 265, 270 are active. However, it should be noted that the inventive method according to an exemplary embodiment can be carried out regardless of whether said components are toothed / active or not.

According to one embodiment, the first control unit 200 is arranged to start up said DOC unit 260. In this case, the first control unit is arranged to control operation of engine and / or supply fuel to said DOC unit 260 by means of said industry metering means 233 in order to effect a temperature increase in the exhaust gas purification system whereby the DOC unit 260, and other components, can be activated / ignited / started. The first control unit 200 is hereby also arranged to prevent / delay start-up of said components by not actively supplying extra fuel to an exhaust stream from said engine 231.

The first control unit 200 is according to one embodiment arranged to control the supply of fuel to said DOC unit 260. The first control unit 200 is according to one embodiment arranged to diagnose said motor 231 and / or industry metering means 233 on the basis of said first NOR content and / or said other NOR content during a non-existent, controlled industry supply per unit time for the DOC unit 260. In this case, industry leakage from said motor 231 and / or said industry dosing means 233 can be determined.

According to one embodiment, the first control unit 200 is arranged to follow changes in said first NOR content and said second NOR content during a period of continuous detection of at least one of said first NOR content and said second NOR content, wherein changes in form of a decrease of fixed NOR content and / or changes in the form of an increase of fixed NOR content only downstream of said DOC unit 250 and / or grazing frequency oscillation of said first NOR content and / or said other NOR content is taken as an indication of the occurrence of fuel in the said exhaust gases. Said fuel occurrence is thereby caused by a leakage from at least one of said motor 231 and said fuel metering means 233.

According to one embodiment, the first control unit 200 is arranged to take a malfunction of said engine 231 and / or industry metering means 233 which is concluded in the event of a signal regarding malfunction due to fuel occurrence in said exhaust gases in connection with the feeding of said first NOR content and / or the feeding of said second NOR content.

Upon exposure to fuel, said first NOR sensor 221 and said second NOR sensor 222 may be affected in such a way that they generate an error signal and send it to the first control unit 200. Said error signal may indicate that the sensor is adversely affected and may be incorrect. varden. The first control unit 200 is arranged to diagnose said engine 231 and / or industry metering means 233 on the basis of said error signal indicating lack of feed function to 1614 of fuel occurrence in said exhaust gases in connection with the feeding of said first NOR content and / or the feeding of said second NOR slippery.

According to one embodiment, the first control unit 200 is arranged to cease with a supply of reducing agent to said exhaust gases in order to improve the determination of a course of said first NOR content and / or said second NOR content. This is particularly applicable in the event that said second NOR sensor 222 is presently arranged downstream of said SCR catalyst arrangement 270. Presenting means 220 are arranged for communication with said first control unit 200 via a long L220. The first control unit 200 is arranged to present a result of said diagnosis of said motor 231 and / or said industry metering means 233. Said result may, for example, indicate "satisfactory function" or "defective function". For example, a degree of impairment of said motor 231 and / or said industry metering means 233 may be presented, this degree of impairment may be stated in percent. Said display means 220 may include loudspeakers for reproducing synthesized rust or other audible feedback. Said display means 220 may include a display screen, for example a so-called touch screen for visual feedback of the said result.

The first control unit 200 is arranged to determine a NOR content of exhaust gases from said internal combustion engine 231. The first control unit 200 is arranged to follow signaling from said NOR sensor. The first control unit 200 is arranged to take changes in the signal of the NON sensor emitted regarding NON content in the exhaust gases and / or error message signaling regarding lack of food function, the said NON sensor has an indication of fuel presence in the exhaust gases from said internal combustion engine. The first control unit 200 can be arranged to follow changes having the said NON content, whereby changes in the form of a decrease of the fixed NOR content and / or changes in the form of an increase of the fixed NOR content only downgrade the said DOC unit 250 and / or High-frequency oscillation has the said NON content taken as an indication of the occurrence of fuel in the said exhaust gases. The first control unit 200 may be arranged to continuously determine NON content in said exhaust gases upstream of existing units having said exhaust purification system. The first control unit 200 may be arranged to continuously determine the NON content of said exhaust gases downstream of an SCR catalyst having said exhaust purification system.

Figure 3a schematically illustrates a diagram according to an embodiment of the invention.

This illustrates how a NON sensor, for example the first NON sensor 221 and the second NON sensor 222, is affected by the occurrence of exhaust gas in the exhaust gas purification system 289. The said NON sensors 221, 222 can be affected in such a way that their output signals are occasionally includes a high frequency oscillating signal, as shown in Figure 3a.

During a period of time between the times T1 and T2 no industry is actively supplied to the said first passage 235.

In addition, the NON sensors exposed to industry exhibit the said high-frequency oscillation, also called the "ripple".

In case at least one of said first NON sensor 221 and said second NON sensor 222 exhibits said ripple, said motor 231 and / or said industry metering unit 233 may be determined to exhibit poor performance. In the event of complete shutdown of active / controlled / requested / desired fuel supply during diagnosis of said motor 231 and / or said fuel metering unit 233, none of said first NON sensor 221 and said second NON sensor 222 shall have said ripple on said motor 231 and / or said industry dosage unit 233 functions as intended, i.e. exhibits satisfactory function / performance. Figure 3b schematically illustrates a diagram, according to an embodiment of the invention. This illustrates how a NON sensor, for example said first NON sensor 221 and said second NOR sensor 222, is affected by the presence of fuel in exhaust gases has said exhaust gas purification system 289. Said NON sensors 221, 222 can be influenced in such a way that their output signals occasionally, a high frequency oscillating signal and a relative decrease in the level of NON content. Figure 3b illustrates said relative decrease with the letter L. Alternatively, said NON sensors 221, 222 may be actuated in such a way that their output signals include a relative decrease of level of NON content, without said high frequency oscillation being edible.

Alternatively, said NON sensor 222, when arranged downstream of said DOC unit, can be actuated in such a way that its output signal includes a relative increase in the level of NON content, without said high frequency oscillation being feedable.

During a period of time between the times T1 to T2 no industry is actively supplied to the said first passage 235.

In this case, said NON sensors exposed to industry exhibit the said high-frequency oscillation and / or the said relative temporary decrease L of the NON content.

In cases where said first NON sensor 221 and / or said second NOR sensor 222 exhibits said decrease in NOR content and / or only said second NON sensor 222 exhibits a relative increase in NON content and / or ripple may motor 231 and / or said industry metering unit 233 are determined to exhibit poor performance. In the event of complete shutdown of active / controlled / requested / desired fuel supply during diagnosis of said motor 231 and / or said fuel metering unit 233, none of said first NON sensor 221 and said second NON sensor 222 shall have said ripple on said motor 231 and / or the said industry dosing unit 233 functions in the intended manner, ie exhibits satisfactory function / performance.

Said relative decrease L may correspond to, for example, 10%.

Figure 3c schematically illustrates a diagram, according to an embodiment of the invention. It is illustrated that a variety of industries paint to said first passage 235, either from said engine 231 or said industry dosing unit 233, or [pada. Active fuel supply to the first passage 235 by means of said motor 231 and said fuel metering unit 233 is completely prevented according to the inventive method. According to this exemplary embodiment, fuel leakage takes place essentially during the said time period T1-T2.

It should be noted that when the first NON sensor 221 and the second NON sensor 222 are exposed to industry, error signals may be sent from the first NON sensor 221 and the second NON sensor 222, respectively, to the first control unit 200. In this case, the inventive method the diagnosis of said DOC unit 260 is performed on the basis of said error signals indicating occurrence of industry of said first NON sensor 221 and said second NOR sensor 222, respectively.

In this case, the following four parameters, individually or in combination, can be used according to the inventive method for diagnosing said motor 231 and / or said industry dosing system 233.

The four parameters are: High frequency oscillation of NOR content; Relative collection of NON content; 3) Fault signaling from NOR sensor; 4) Relative increase in NOR content of only one NOR sensor downstream of the said DOC unit 250.

Examples of reasons that fuel leakage can occur in the said internal combustion engine can be at least flaws of incomplete combustion, too low temperature in the fuel / engine and incorrect dosing pressure in the engine.

Examples of reasons that industry leakage may occur at said industry dosing unit 233 may be at least flakes of excessive dosing, 26 incorrect dosing pressure, defective nozzle and leakage during a phase (which industry should not be dosed.

Figure 4a schematically illustrates a flow chart of a method for determining fuel occurrence in exhaust gases from an internal combustion engine 231 with an exhaust gas purification system comprising at least one NOR sensor 221, 222 arranged downstream of said internal combustion engine 231. The method comprises a first process step. Step s401 includes the steps of: - determining a NOR content of exhaust gases from said combustion engine 231; - follow signaling from the said NOR sensor 221, 222; and - take changes has the signal of the NOR sensor 221, 222 regarding NOR content in the exhaust gases and / or error message signaling regarding lack of food function has the said NOR sensor 221, 222 as an indication of fuel occurrence in the exhaust gases from said combustion engine 231. After the procedure step s401 the procedure ends. .

Figure 4b schematically illustrates a flow chart of a method for determining fuel occurrence in exhaust gases from an internal combustion engine 231 with an exhaust gas purification system comprising at least one NOR sensor arranged downstream of said internal combustion engine 231.

The process includes a first process step s410. The process step s410 comprises the step of determining at least one NOR content has exhaust gases from said internal combustion engine 231. This may be done by means of said first NOR sensor 221 and / or said second NOR sensor 222. The process step s410 may comprise the step of following signaling from said at least one NOR sensor.

The method step s410 may comprise the steps of continuously determining said first NON content by means of said first NOR sensor 221 and continuously determining said second NOR content by means of said second NOR sensor 222.

The process step s410 may include the step of determining a radiating temperature having exhaust gases from said engine 231. Alternatively, a radiating temperature may have at least one of said DOC unit 260, DPF unit 265 and SCR catalyst arrangement 270. This may be conveniently done. The respective 27 temperatures can be fed directly by means of a temperature sensor. Alternatively, said respective temperatures can be modeled / calculated / estimated / determined in an appropriate manner, for example by means of said first control unit 200 on the basis of a fixed exhaust gas temperature in the first passage 235 and / or a fixed exhaust gas mass flow.

In this case, it can be determined whether at least one of the said components is active / tooth or not. Determination of NOR content to determine possible fuel occurrence of exhaust gases from said engine 231 takes place according to an exemplary embodiment only downstream of a component that is not active / tooth. After the procedure step s410, a subsequent procedure step s420 is performed.

The method step s420 comprises the step of detecting error signaling from at least one NOR sensor of said exhaust gas purification system.

The method step s430 may then include the step of determining whether error signaling from the first NOR sensor 221 and the second NON sensor 222 occurs. This can be done by means of the first control unit 200.

When diagnosing said internal combustion engine 231 and / or said fuel metering unit 233, active fuel supply to the engine 231 exhaust gases is prevented.

After the procedure step s420, a subsequent procedure step s430 is performed.

According to one embodiment, reducing agent dosing by means of said dosing unit 250 is completely turned off. According to one embodiment, a variable reducing agent dosage may be provided by said dosage unit 250.

According to these embodiments, advantageously improved detection of NOR content in exhaust gases can be achieved.

Step s430 may include the step of determining the occurrence of at least a flag of the four parameters / pitches: 1) High frequency oscillation of at least one of said first NOR content and said second NOR content; 2) Relative collection of at least one of said first NOR content and said second NOR content; Error signaling from at least one of said first NOR sensor 221 and said second NOR sensor 222; Relative increase of NOR content has only one NOR sensor downstream of the said DOC unit 250.

After the step step s430, a subsequent step s440 is performed.

Step s440 may include the step of diagnosing said motor 231 and / or said industry dosing unit 233 on the basis of signaling from said first NOR sensor 221 and / or said second NOR sensor 222. Said diagnosis may be performed by said first control unit 200 according to routines. Said diagnosis can be performed on the basis of said first NOR content and / or said second NOR content. Said diagnosis can be performed on the basis of at least a flag of the parameters / pitches 1-4, which are indicated in procedure step s430 above. Said diagnosis can be performed on the basis of said error signaling.

Said diagnosis of said engine 231 and / or said fuel metering unit 233 can be performed during shut off active fuel supply to said exhaust gases from said engine 231. According to an exemplary embodiment, all of the components DOC unit 260, DP F unit 26 and SCR catalyst arrangement 270 are not active / toothed.

Said diagnosis of said motor 231 and / or said industry metering unit 233 may include determining erasing performance and / or a mat of performance degradation relative to a reference condition. Said reference condition may be a condition in which said engine 231 and / or said fuel metering unit 233 have not been used and are newly manufactured. Said reference state may be a predetermined state, which may be empirically determined. Step s440 may include the step of taking changes in at least one of said first or second NOR sensors emitted signal regarding NON content in the exhaust gases and / or error message signaling regarding malfunction of said NON sensor as an indication of industry occurrence in the exhaust gases said combustion engine. 29 After the procedure step s440, a subsequent procedure step s450 is performed.

The method step s450 comprises the step of presenting a result of said diagnosis of said internal combustion engine 231 and / or said fuel metering unit 233. This can be done by said display means 220 and said first control unit 200. In this case a result concerning said diagnosis can be presented to, for example, an operator of the vehicle. , driver or service personnel. After step step s450, the procedure ends.

Referring to Figure 5, there is shown a diagram of an embodiment of a device 500. The controllers 200 and 210 described with reference to Figure 2a and Figure 2b may in one embodiment include the device 500. The device 500 includes 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 portion 530 of a computer program, such as an operating system, stored to control the operation of the device 500. Further, the device 500 includes a bus controller, a serial communication port, I / O means, an A / D converter, a time and date input and transfer unit, a trade calculator and an interrupt controller (not shown). The non-volatile memory 520 also has a second memory portion 540.

A computer program P is provided for determining fuel occurrence in exhaust gases from an internal combustion engine 231 with an exhaust gas purification system comprising at least one NOR sensor 221, 222 arranged downstream of said internal combustion engine 231.

The computer program P may comprise routines for determining a NOR content of exhaust gases from said internal combustion engine 231. The computer program P may comprise routines for following signaling from said NON sensor. The computer program P may include routines for making changes if the signal Si, S2 of the NOx sensor 221, 222 emitted regarding NOR content in the exhaust gases and / or error message signaling regarding malfunction has the said NOR sensor 221, 222 as an indication of industry occurrence in the exhaust gases from said combustion engine 231. The computer program P may comprise routines for following changes in said NOR content, changes in the form of a decrease in a fixed NOR content and / or changes in the form of an increase in a fixed NON content in only one NOR content. sensor downstream of the said DOC unit 250 and / or high-frequency oscillation has the said NON content taken as an indication of the fuel presence in the said exhaust gases. The computer program P may comprise routines for continuously determining the NON content in said exhaust gases upstream of existing units having said exhaust gas purification system. The computer program P may comprise routines for continuously determining NON content in said exhaust gases downstream of an SCR catalyst having said exhaust purification system.

The computer program P may include routines for determining a first NON content of 10 exhaust gases upstream of a DOC unit 260. The computer program P may include routines for determining a second NON content of exhaust gases downstream of said DOC unit 260. The computer program P may include routines. to diagnose said motor 231 and / or said fuel metering unit 233 on the basis of said first NON content and / or said second NON content during a substantially eliminated active fuel supply per unit time for the DOC unit 260. The computer program P may comprise routines for diagnosing said motor 231 and / or said industry dosing unit 233 on the basis of said first NON content and / or said second NON content.

The computer program P may comprise routines for following changes in said first NON content and / or said second NON content during a period of said eliminated industry supply, whereby changes in the form of a reduction of fixed NON content and / or changes in the form of an increase of the fixed NON content has only a NON sensor downstream of said DOC unit 250 and / or high frequency oscillation has said first NOR content and / or said second NOR content taken as an indication of fuel occurrence in said exhaust gases.

The computer program P may comprise routines for taking malfunction of said engine 231 and / or said fuel metering unit 233 which is concluded in the event of a signal regarding malfunction due to fuel occurrence in said exhaust gases in connection with the feeding of said first NON content and / or the feed. of the said other NON content. The computer program P may comprise routines for ceasing a supply of reducing agent to said exhaust gases in order to improve the determination of a course of said first NOR content and / or said second NOR content.

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

When it is described that the data processing unit 510 performs a certain function, it should be understood that the data processing unit 510 outputs a certain part of the program which is stored in the memory 560, or a certain part of the program which is stored in the read / write memory 550.

The data processing device 510 can 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 to communicate with the data processing unit 510 via a data bus 511. Read / the write memory 550 is arranged to communicate with the data processing unit 510 via a data bus 514. To the data port 599, e.g. the lanes L210, L250, L292, L221, L222, L233 and L241 are connected (see Figure 2a and Figure 2b).

When data is received on the data port 599, it is temporarily stored in the second memory part 540. Once the received input data has been temporarily stored, the data processing unit 510 is ready to perform code execution in a manner described above. According to one embodiment, signals received at the data port 599 include information about a said first NOR content and said second NOR content. According to one embodiment, signals received at the data port 599 include the estimated / calculated / matte / fixed / modeled temperature of at least one component of the system 289, for example, the DOC unit 260. According to one embodiment, signals received at the data port 599 include information about whether said at least one component is active or not.

Parts of the methods described herein may be performed by the device 500 using the data processing unit 510 which the cat program has stored in the memory 560 or 32 read / write memory 550. When the device 500 runs the program, the methods described are executed.

The foregoing description of the preferred embodiments of the present invention has been provided for the purpose of illustrating and describing the invention. It is not intended to be exhaustive or to limit the invention to the variations described. Obviously, many modifications and variations will occur to those skilled in the art. The embodiments were selected and described in order to best explain the principles of the invention and its practical applications, thereby enabling those skilled in the art to understand the invention for various embodiments and with the various modifications which are appropriate to the intended use. 33

Claims (14)

Patent claims A method for determining fuel occurrence in exhaust gases from an internal combustion engine (231) with an exhaust gas cleaning system comprising at least one NON sensor (221; 222) arranged downstream of said internal combustion engine (231), comprising the step of: - determining (s410) a NOR content in exhaust Iran fuel combustion engine (231); characterized by the steps of: - following signaling (s410) from said NOR sensor; and - take (s440) changes in the signal emitted by the NOR sensor (221; 222) (Si; S2) regarding NOR content in the exhaust gases and / or error message signaling regarding lack of food function has the said NOR sensor (221; 222) as an indication of industry occurrence in the exhaust gases from the said internal combustion engine (231). A method according to claim 1, comprising the step of: - following changes having said NOR content, wherein changes in the form of a decrease of a fixed NON content and / or changes in the form of an increase of a fixed NOR content have only a NOR sensor downstream of a DOC unit 250 and / or high-frequency oscillation, the said NOR content is taken as an indication of the occurrence of fuel in the said exhaust gases. A method according to claim 1 or 2, comprising the step of: - continuously determining the NOR content in said exhaust gases upstream of existing units having said exhaust gas purification system. A method according to any one of claims 1-3, comprising the step of: - continuously determining the NON content in said exhaust gases downstream of an SCR catalyst (270) having said exhaust gas purification system. A system for determining fuel occurrence in exhaust gases from an internal combustion engine (231) with an exhaust gas purification system comprising at least one NOR sensor (221; 222) arranged downstream of said internal combustion engine (231), comprising: - at least one NOR sensor (221; 222) adapted to determine a NON content of exhaust gases from said internal combustion engine (231); 34 characterized by: - means (200; 210; 500) adapted to detect changes in signaling emitted from said NOR sensor (221; 222) regarding NOR content in the exhaust gases; and / or means (200; 210; 500) adapted to detect error message signaling due to malfunction of said NOR sensor (221; 222); and - means (200; 210; 500) adapted to determine the fuel presence in the exhaust gases of the said internal combustion engine (231) on the basis of said detected changes of the signal emitted from the NOR sensor (221; 222) regarding NOR content in the exhaust gases and the said detected error message signaling. The system of claim 5, further comprising: - means (200; 210; 500) adapted to track changes in said NOR content; means (200; 210; 500) arranged to take changes in the form of a decrease in a fixed NOR content and / or changes in the form of an increase in a fixed NOR content of only one NOR sensor downstream of a DOC unit 250, and / or high-frequency oscillation at the said NOR content as an indication of the occurrence of fuel in the said exhaust gases. A system according to claim 5 or 6, comprising: - means (200; 210; 500; 221) adapted to continuously determine NOR content in said exhaust gases upstream of existing units of said exhaust gas purification system. A system according to any one of claims 5-7, comprising: - means (200; 210; 500; 221; 222) adapted to continuously determine NOR content in said exhaust gases downstream of an SCR catalyst of said exhaust gas purification system. A system according to any one of claims 5-8, comprising: - means (200; 210; 500; 220) adapted to indicate the presence of fuel in the exhaust gases from said internal combustion engine. A system according to any one of claims 5-9, comprising: - an industry metering unit (233) arranged upstream of existing units (260; 265; 270) of said exhaust gas purification system, and - means (200; 210; 500) adapted to the exhaust gases from said internal combustion engine (231) take this as an indication of fuel leakage from said internal combustion engine (231) and / or from said fuel metering unit (233). A motor vehicle (100; 110) comprising a system according to any of claims 5-10. A motor vehicle (100; 110) according to claim 11, wherein the motor vehicle is any of a truck, bus or passenger car. A computer program (P) for determining the fuel presence of exhaust gases from an internal combustion engine (231) having an exhaust gas purification system comprising at least one NON sensor (221; 222) arranged downstream of said internal combustion engine (231), said computer program (P) comprising program code for cause an electronic control unit (200; 500) or another computer (210; 500) connected to the electronic control unit (200; 500) to perform the steps according to any one of claims 1-4. A computer program product comprising a program code stored on a computer readable medium for performing the method steps of any of claims 1-4, when said program code is crossed on an electronic control unit (200; 500) or another computer (210; 500) connected to the electronic control unit (200; 500). 1 / or 100 112