BR112020004571A2 - system and method for diagnosing an emission control arrangement for a combustion engine - Google Patents

Abstract

The invention relates to a method for diagnosing an emission control arrangement for a combustion engine (231) in operation, comprising at least a first SCR configuration (260) and a second SCR configuration (270) arranged in series. The method comprises the steps of: - determining (s420) a first degree of reduction of NOx content for the first SCR configuration (260); - determine (s425) a second degree of reduction of NOx content for the second SCR configuration (270); -determine (s430) a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - compare (s435) the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - determine (s440) that the emission control arrangement is operating as desired if the total degree of NOx content reduction exceeds the predetermined reference degree of NOx content reduction. The invention also relates to a program product computer comprising program code (P) for a computer (200; 210; 500) to implement a method according to the invention. The invention also relates to a system for diagnosing an emission control arrangement for a combustion engine in operation, comprising at least a first SCR configuration and a second SCR configuration arranged in series, and a motor vehicle (100) equipped with the system.

Description

“SYSTEM AND METHOD FOR DIAGNOSING AN EMISSION CONTROL ARRANGEMENT FOR A COMBUSTION ENGINE” TECHNICAL FIELD

[0001] The present invention relates to a method for diagnosing an emission control arrangement for an operating combustion engine. The invention also relates to a computer program product comprising program code for a computer to implement a method according to the invention. It also refers to a system for diagnosing an emission control arrangement for a combustion engine in operation and a motor vehicle equipped with the system.

BACKGROUND OF THE TECHNIQUE

[0002] Emission control systems for vehicle combustion engines are now arranged with catalytic configurations, for example, for conversion of NOx gas. Emission control systems may comprise a DOC unit (diesel oxidation catalyst), unit DPF (diesel particulate filter), SCR unit (selective catalytic reduction) and an ammonia slip catalyst. In this system, a reducing agent is provided to reduce the NOx content prevalent in the engine's exhaust gases.

[0003] It is necessary to determine a total degree of reduction of NOx content for the emission control system that comprises SCR units. In a case where the emission control system comprises two or more SCR units arranged in series, it is common to determine the total degree of reduction of the NOx content based on the measured NOx content of an exhaust gas from the downstream engine. engine and NOx content measured in an exhaust pipe downstream of SCR units. This method works satisfactorily today, but as national / regional laws, regulations and guidelines continually increase demands to reduce the NOx content of exhaust gases from, for example, heavy vehicles, there is a need to improve existing methods for determine the total degree of reduction of NOx content for an emission control system comprising SCR units.

[0004] US 2014/0106460 A1 refers to a method for controlling and / or diagnosing an emission control system for a vehicle that has a first SCR region upstream of a second SCR region.

[0005] US 2017/0051654 Al discloses an apparatus comprising a structured nitrogen oxide module to determine a failure in the NOx conversion efficiency based on the amount of NOx exiting the engine and the amount of NOx exiting the after-treatment system exhaust, and a structured SCR diagnostic module to determine which of a DFP-SCR and an SCR is responsible for the efficiency failure.

SUMMARY OF THE INVENTION

[0006] An objective of the present invention is to propose a new and advantageous method for diagnosing an emission control arrangement for an operating combustion engine.

[0007] Another objective of the invention is to propose a new and advantageous system and a new and advantageous computer program to diagnose an emission control arrangement for an operating combustion engine.

[0008] Another objective of the present invention is to propose a new and advantageous method that provides an economical and reliable diagnosis of an emission control arrangement for an operating combustion engine.

[0009] Another objective of the invention is to propose a new and advantageous system and a new and advantageous computer program that provides an economical and reliable diagnostic functionality of an emission control arrangement for an operating combustion engine.

[0010] Yet another objective of the invention is to propose a method, a system and a computer program that achieve a robust, accurate and automated diagnostic functionality of an emission control arrangement for an operating combustion engine.

[0011] Yet another objective of the invention is to propose an alternative method, an alternative system and an alternative computer program to diagnose an emission control arrangement for an operating combustion engine.

[0012] Some of these objectives are achieved with a method according to claim 1. Other objectives are achieved with a system according to what is represented here. Advantageous modalities are represented in the dependent claims. Substantially, the same advantages of the steps of the innovative method are true for the corresponding means of the innovative system.

[0013] In accordance with one aspect of the invention, a method is provided for diagnosing an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration and a second SCR configuration arranged in series, the method comprising the steps of: - determining a set of values of operational parameters for the emission control arrangement; - determining and dosing a quantity of reducing agent for the first SCR configuration to obtain a predetermined NOx content downstream of the first SCR configuration; - determining and dosing a quantity of reducing agent for the second SCR configuration to obtain a predetermined NOx content downstream of the second SCR configuration; - determine a first degree of reduction of NOx content for the first SCR configuration; - determine a second degree of reduction of NOx content for the second SCR configuration; - determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - compare the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - determine that the emission control arrangement is operating as desired if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction.

[0014] If it is determined that the emission control arrangement is not operating as desired, the method may further comprise generating an error message for the emission control arrangement.

[0015] The first SCR configuration is arranged upstream of the second SCR configuration.

[0016] In the step of determining and dosing a quantity of reducing agent for the first SCR configuration to obtain a predetermined NOx content downstream of the first SCR configuration, the predetermined NOx content downstream of the first SCR configuration can be upstream of the second SCR configuration.

[0017] The determination of a quantity of reducing agent for the first SCR configuration to obtain a predetermined NOx content downstream of the first SCR configuration can be performed based on one or more of the parameter values of the operational parameter values. Likewise, the determination of an amount of reducing agent for the second SCR configuration to obtain a predetermined NOx content downstream of the second SCR configuration can be carried out based on one or more of the parameter values of the operational parameter values.

[0018] The set of operational parameter values may comprise a predominant mass flow of exhaust gases from the combustion engine. The set of operating parameter values can comprise a predominant temperature of the first SCR configuration. The set of operational parameter values can comprise a predominant temperature of the second SCR configuration. The set of operational parameter values can comprise a predominant NOx content downstream of the combustion engine and upstream of the first SCR configuration. The set of operating parameter values can comprise the example parameters specified above in any combination.

[0019] The predetermined NOx content downstream of the first SCR configuration can be selected or determined based on a predetermined NOx content downstream of the combustion engine and upstream of the first SCR configuration.

[0020] The predetermined NOx content downstream of the second SCR configuration can be selected or determined based on a predetermined NOx content downstream of the first SCR configuration and upstream of the second SCR configuration.

[0021] The total degree of NOx content reduction for the emission control arrangement is determined on the basis of the first degree of NOx content reduction and the second degree of NOx content reduction thus determined, and not just on the basis of the predominant NOx content upstream of the first SCR configuration and the predominant NOx content downstream of the second SCR configuration. This has, among others, the advantage of reducing the risk of errors by the total determined degree of NOx content reduction and, therefore, increases the precision in the diagnosis of the emission control arrangement.

[0022] The predetermined degree of reference for reducing the NOx content can be determined according to the national / regional laws / regulations / directives in force. The predetermined degree of reference for reducing the NOx content can be, for example, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99%.

[0023] By this means, a reliable and accurate method is achieved, according to an embodiment of the invention.

[0024] The method can also comprise the steps of: - comparing the first degree of NOx content reduction for the first SCR configuration with a first predetermined degree of NOx content reduction; and - determine that the first SCR configuration is operating as desired if the first degree of NOx content reduction exceeds the predetermined first degree of NOx content reduction and, if not, generate an error code for the first SCR configuration .

[0025] By this means, an accurate and reliable way of diagnosing the first SCR configuration is advantageously achieved.

[0026] The first predetermined degree of reference for reducing the NOx content can be, for example, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99%.

[0027] The method can also comprise the steps of: - comparing the second degree of NOx content reduction for the second SCR configuration with a second predetermined degree of NOx content reduction; and - determine that the second SCR configuration is operating as desired if the second degree of NOx content reduction exceeds the predetermined second degree of NOx content reduction and, if not, generate an error code for the second SCR configuration .

[0028] By this means, an accurate and reliable way of diagnosing the first SCR configuration is advantageously achieved.

[0029] The second predetermined degree of reference for reducing the NOx content can be, for example, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99%.

[0030] The method may comprise the step of: - including in the emission control arrangement other SCR configurations in series and applying corresponding degrees of NOx reduction determinations to the emission control arrangement thus extended, totally and individually.

[0031] By this means, a versatile method is achieved. The inventive method is applicable to the emission control arrangement with a plurality of SCR configurations.

[0032] The method may comprise the step of: - including in the emission control arrangement other SCR configurations in parallel and applying corresponding degrees of NOx reduction determinations to the emission control arrangement thus extended, totally and individually.

[0033] By this means, a versatile method is achieved. The inventive method is applicable to the emission control arrangement with a plurality of SCR configurations.

[0034] In accordance with one aspect of the invention, a system is provided to diagnose an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration and a second SCR configuration arranged in series, the system comprising: - means arranged to determine a set of values of operational parameters for the emission control arrangement; - means arranged to determine and dose an amount of reducing agent for the first SCR configuration to obtain a predetermined NOx content downstream of the first SCR configuration; - means arranged to determine and dose an amount of reducing agent for the second SCR configuration to obtain a predetermined NOx content downstream of the second SCR configuration; - means arranged to determine a first degree of reduction of NOx content for the first SCR configuration; - means arranged to determine a second degree of reduction of NOx content for the second SCR configuration; - means arranged to determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - means arranged to compare the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - means arranged to determine that the emission control arrangement is operating as desired, if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction.

[0035] The system may comprise: - means arranged to compare the first degree of NOx content reduction for the first SCR configuration with a first predetermined degree of NOx content reduction; and - means arranged to determine that the first SCR configuration is operating as desired if the first degree of NOx content reduction exceeds the first predetermined degree of NOx content reduction and, if not, to generate an error code for the first SCR configuration.

[0036] The system may comprise: - means arranged to compare the second degree of NOx content reduction for the second SCR configuration with a second predetermined degree of NOx content reduction; and - means arranged to determine that the second SCR configuration is operating as desired if the second degree of NOx reduction exceeds the predetermined second degree of NOx reduction reference and, if not, to generate an error code for the second SCR configuration.

[0037] The system can comprise: - other SCR configurations in series; and - means for applying corresponding degrees of NOx reduction determination determinations for the emission control arrangement thus fully and individually expanded.

[0038] The system can comprise: - other SCR configurations in parallel; and - means for applying corresponding degrees of NOx reduction determination determinations for the emission control arrangement thus fully and individually expanded.

[0039] According to one aspect of the invention, a vehicle is provided comprising a system according to what is presented here. The vehicle can be any vehicle among a truck, bus or passenger car. According to one modality, the system is provided for a marine or industrial application.

[0040] In accordance with one aspect of the invention, a computer program is provided to diagnose an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration and a second configuration SCR arranged in series, in which the computer program comprises program code to cause an electronic control unit or a computer connected to the electronic control unit to perform any of the steps of the method described here, when executed in the electronic control unit or on the computer.

[0041] In accordance with an aspect of the invention, a computer program is provided to diagnose an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration and a second configuration SCR arranged in series, in which the computer program comprises program code stored in a computer readable medium to cause an electronic control unit or a computer connected to the electronic control unit to perform any of the steps of the method described here.

[0042] In accordance with an aspect of the invention, a computer program is provided to diagnose an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration and a second configuration SCR arranged in series, in which the computer program comprises program code stored in a computer-readable medium to cause an electronic control unit or a computer connected to the electronic control unit to perform any of the steps of the method described here, when run on the electronic control unit or the computer.

[0043] In accordance with an aspect of the invention, a computer program product is provided that contains a program code stored in a computer-readable medium to perform any of the steps of the method described here, when the computer program is executed on an electronic control unit or on a computer connected to the electronic control unit.

[0044] In accordance with one aspect of the invention, a computer program product is provided that contains a non-volatile program code stored in a computer-readable medium to perform any of the steps of the method described here, when the computer program runs on an electronic control unit or on a computer connected to the electronic control unit.

[0045] In accordance with one aspect of the invention, a method is provided for diagnosing an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration and a second SCR configuration arranged in series, the method comprising the steps of: - determining a first degree of reduction of NOx content for the first SCR configuration; - determine a second degree of reduction of NOx content for the second SCR configuration; - determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - compare the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - determine that the emission control arrangement is operating as desired if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction.

[0046] In accordance with one aspect of the invention, a system is provided to diagnose an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration and a second SCR configuration arranged in series, the system comprising: - means arranged to determine a first degree of reduction in the content of

NOx for the first SCR configuration; - means arranged to determine a second degree of reduction of NOx content for the second SCR configuration; - means arranged to determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - means arranged to compare the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - means arranged to determine that the emission control arrangement is operating as desired, if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction.

[0047] Other objectives, advantages and new features of the present invention will be evident to a person skilled in the art from the following details, and also putting the invention into practice. While the invention is described below, it should be noted that it is not confined to the specific details described. A person skilled in the art who has access to the teachings presented here will recognize other applications, modifications and incorporations in other fields, which are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] For a more complete understanding of the present invention and its other objectives and advantages, the detailed description set out below should be read in conjunction with the accompanying drawings, in which the same reference notations indicate similar items in the various diagrams, and in which :

[0049] Figure 1 schematically illustrates a vehicle according to an embodiment of the invention;

[0050] Figure 2a schematically illustrates a system according to an embodiment of the invention;

[0051] Figure 2b schematically illustrates a system according to an embodiment of the invention;

[0052] Figure 2c schematically illustrates a system according to an embodiment of the invention;

[0053] Figure 2d schematically illustrates a system according to an embodiment of the invention;

[0054] Figure 2e schematically illustrates a system according to an embodiment of the invention;

[0055] Figure 2f schematically illustrates a system according to an embodiment of the invention;

[0056] Figure 3 schematically illustrates a diagram according to an aspect of the invention;

[0057] Figure 4a is a schematic flow chart of a method according to an embodiment of the invention;

[0058] Figure 4b is a schematic function diagram of a method according to an embodiment of the invention; and

[0059] Figure 5 schematically illustrates a computer according to an embodiment of the invention.

DETAILED DESCRIPTION

[0060] Figure 1 represents a side view of a vehicle 100. The exemplified vehicle 100 comprises a tractor unit 110 and a trailer 112. Vehicle 100 can be a heavy vehicle, for example, a truck or a bus. It can, alternatively, be a car.

[0061] The inventive method and system are applicable to various vehicles, such as a mining machine, tractor, dumper, backhoe, platform comprising an industrial robot, forest machine, excavator, road construction vehicle, road planner , emergency vehicle or a tracked vehicle.

[0062] The inventive method and system are applicable to several reducing agent dosing systems comprising at least two SCR units being arranged in series.

[0063] The invention is suitable for application in various systems comprising a combustion engine and an associated emission control arrangement comprising a reducing agent dosing system with at least two SCR units arranged in series. The invention is suitable for application in various systems comprising a combustion engine and a catalytic configuration having at least two SCR units being arranged in series. The catalytic configuration may comprise at least one reducing agent dosing unit, each dosing unit being arranged to provide a reducing agent upstream of a corresponding SCR unit. The catalytic configuration can comprise one or more DOC units. The catalytic configuration can comprise one or more DPF units. It should be noted that the invention is applicable to various catalytic configurations and is therefore not confined to catalytic configurations for motor vehicles. The innovative method and the innovative system according to one aspect of the invention are well suited for other platforms comprising a combustion engine and a catalytic configuration having at least two SCR units arranged in series in addition to motor vehicles, for example, vessels. The vessel can be of any type, for example, motor boats, steam boats, ferries or ships.

[0064] The innovative method and the innovative system according to an aspect of the invention are also suitable for, for example, systems comprising industrial combustion engines and / or industrial robots powered by combustion engines and an associated emission control arrangement comprising at least two SCR units being arranged in series.

[0065] The innovative method and the innovative system according to one aspect of the invention are also well suited for various types of power plants, for example, an electric power plant comprising a generator powered by a combustion engine and a control arrangement of associated emissions comprising at least two SCR units arranged in series.

[0066] The innovative method and the innovative system are also suitable for various combustion engine systems comprising an associated emission control arrangement having at least two SCR units arranged in series.

[0067] The innovative method and the innovative arrangement are well suited for any engine system comprising an engine, for example on a locomotive or some other platform, and an associated emission control arrangement having at least two SCR units arranged in series .

[0068] The innovative method and the innovative system are well suited for any system comprising a NOx generator and an emission control arrangement associated with at least two SCR units arranged in series.

[0069] The term "connection" here refers to a communication connection that can be a physical connection, such as an optoelectronic communication line, or a non-physical connection, such as a wireless connection, for example, a radio or microwave connection.

[0070] The term "line" here refers to a passage to retain and transport a fluid, for example, a reducing agent in liquid or fuel form. The line can be a tube of any size and can be made of any suitable material, for example, plastic, rubber or metal.

[0071] The term "reducing" or "reducing agent" here refers to an agent used to react with certain emissions in an SCR system. These emissions can, for example, be NOx gas. The terms "reducing" and "reducing agent" are used interchangeably here. In one version, the reducer is a solution containing urea, such as the so-called AdBlue. Other types of reducers can, of course, be used. AdBlue is cited here as an example of a reducer, but one skilled in the art will appreciate that the innovative method and the innovative system are feasible with other types of reducers.

[0072] The terms "SCR unit" and "SCR configuration" are used interchangeably here. The SCR unit / SCR configuration can also be referred to as a "reduction catalyst device". The SCR units in the emission control arrangement can be any suitable SCR units. According to an example, the SCR unit can comprise an SCRF unit, comprising a coated filter. The SCR unit can, according to other examples, provide a combination of SCR functionality and at least one additional functionality (other than NOx conversion), such as SCR functionality and DOC functionality, SCR functionality and ammonia catalyst functionality, etc. . The SCR unit can comprise ceramic materials used as carriers, such as titanium oxide, and active catalytic components that are generally oxides of common metals, such as vanadium, molybdenum and tungsten.

[0073] Figure 2a schematically illustrates a system 291 according to an example embodiment of the invention. The 291 system is located on tractor unit 110 and can be part of an emission control arrangement. The emission control arrangement can alternatively be indicated as an exhaust gas processing configuration. In this example, it comprises a tank 205 arranged to hold a reducer. The 205 tank is adapted to maintain an adequate amount of reducer and also to be refilled as needed. The 205 tank can be adapted to hold, for example, 75 or 50 liters of reducer.

[0074] A first line 271 is provided to drive the gear unit to a pump 230 from tank 205. Pump 230 can be any suitable pump. Pump 230 can be arranged to be driven by an electric motor (not shown). The pump 230 can be adapted to extract the reducer from the tank 205 via the first line 271 and supply it via a second line 272 to a first dosing unit 237a and a second dosing unit 237b. A valve unit 221 is arranged downstream of the second metering unit 237b. The reducer is pressurized downstream of pump 230 and upstream of valve unit 221. Thus, the reducer is supplied under pressure for the first metering unit 237a and the second metering unit 237b. The first dosing unit 237a and the second dosing unit 237b can also be referred to as a reducing agent dosing unit. Each dosing unit 237a and 237b comprises an electrically controlled metering valve by means of which a flow of reducer added to the exhaust system can be controlled. The pump 230 is adapted to pressurize the reducer in the second line 272. The reducer pressure is accumulated in the system 291 by the valve unit 221. The operation of the valve unit 221 can be controlled by a first control unit 200.

[0075] The first control unit 200 is arranged for communication with the pump 230 through an L230 connection. The first control unit 200 is arranged to send control signals S230 via the L230 connection. The first control unit 200 is arranged to control the operation of the pump 230, in order, for example, to adjust the flows of the reducing agent within the system 299. The first control unit 200 is arranged to control an operating power of the pump 230, for example, controlling the electric motor.

[0076] Dosing units 237a and 237b are adapted to supply the reducer to an exhaust system (see Fig. 2b) of vehicle 100. More specifically, they are adapted to supply an adequate amount of reducer in a controlled manner to a system exhaust system of the vehicle 100. In this version, two SCR units (see Fig. 2b and Fig. 2c) are located downstream from their respective locations in the exhaust system where the gear unit is supplied.

[0077] A third line 273 running between the throttle unit 221 and the tank 205 is adapted to bring back to the tank 205 a certain amount of reducer fed to the dosing units 237a and 237b. This configuration results in an advantageous cooling of the dosing units 237a and 237b.

[0078] Dosing units 237 and 237b are therefore cooled by a flow from the reducer when it is pumped through them from pump 230 to the tank

205.

[0079] The first control unit 200 is arranged for communication with the first dosing unit 237a via a connection L237a. The first control unit 200 is arranged to send control signals S237a over link L237a. The first control unit 200 is arranged to control the operation of the first dosing unit 237a, in order, for example, to control the dosing of the reducing agent for the vehicle exhaust system 100.

[0080] The first control unit 200 is arranged for communication with the second dosing unit 237b through a connection L237b. The first control unit 200 is arranged to send control signals S237b via the L237b link. The first control unit 200 is arranged to control the operation of the first dosing unit 237b, in order, for example, to control the dosing of the reducing agent for the vehicle exhaust system 100.

[0081] The first control unit 200 is arranged to control the operation of the first dosing unit 237a and the second dosing unit 237b independently.

[0082] A second control unit 210 is arranged for communication with the first control unit 200 through an L210 connection. It can be removably connected to the first control unit 200. It can be a control unit external to the vehicle 100. It can be adapted to one or more steps of the method disclosed here. It can be used to load software onto the first control unit 200, particularly software to apply the innovative method. Alternatively, it can be arranged for communication with the first control unit 200 through an internal network on board the vehicle 100. It can be adapted to perform functions corresponding to those of the first control unit 200, such as diagnosing a control control arrangement. emissions for a combustion engine in operation, comprising at least a first SCR configuration and a second SCR configuration arranged in series.

[0083] Figure 2b schematically illustrates a vehicle system 292 shown in Figure 1 according to an embodiment of the invention. The system 292 can form a part of the inventive system for diagnosing an emission control arrangement for an internal combustion engine 231 in operation, comprising at least a first SCR configuration and a second SCR configuration arranged in series.

[0084] The internal combustion engine 231 is, during operation, causing an exhaust gas flow that is conducted through a first passage 255 to a first SCR 260 unit. A second passage 255 is arranged to transport the gas flow exhaust from the first SCR 260 unit to the second SCR 270 unit. A third passage 275 is arranged to carry the exhaust gas flow from the second SCR 270 unit to an emission control arrangement environment. It should be noted that the first SCR 260 unit and the second SCR 270 unit are arranged in series. The emission control arrangement may further comprise one or more DOC units (not shown). The emission control arrangement may further comprise one or more ammonia slip catalysts (not shown). The emission control arrangement may further comprise one or more DOC units (not shown).

[0085] The first dosing unit 237a is arranged to supply the reducer to the first passage 255 upstream of the first SCR unit 260 and downstream of the motor 231. The first dosing unit 237a is arranged to supply the reducer for use of the first unit SCR 260. The first control unit 200 is arranged to control the operation of the first dosing unit 237a so that, when applicable, dosing reducing agent in the first passage 255.

[0086] The second dosing unit 237b is arranged to supply the reducer to the second passage 265 upstream of the second SCR unit 270 and downstream of the first SCR unit 260. The second dosing unit 237b is arranged to supply the reducer for use in the second SCR 270 unit. The first control unit 200 is arranged to control the operation of the second dosing unit 237b so that, when applicable, dosing reducing agent upstream of the second SCR 270 unit.

[0087] In the case where more than two SCR units are arranged in series in the emission control arrangement, a respective dosing unit is arranged upstream of each of the additional SCR units.

[0088] The first control unit 200 is arranged to perform the process steps described here, comprising the process steps that are detailed with reference to Figure 4b.

[0089] Figure 2c schematically illustrates a vehicle system 293 shown in Figure 1 according to an embodiment of the invention. The 299 system can form a part of the inventive system for diagnosing an emission control arrangement for an operating combustion engine, comprising at least a first SCR configuration and a second SCR configuration arranged in series.

[0090] An exhaust gas mass flow sensor 247 is arranged to determine an MF mass flow of the predominant exhaust gases in the first passage 255. The exhaust gas mass flow sensor 247 is arranged for communication with the first control unit 200 via an L247 connection. The exhaust gas mass flow sensor 247 is arranged to send signals S247 comprising information about the mass flow MF of the predominant exhaust gases to the first control unit 200 via the L247 connection.

[0091] According to one embodiment, the first control unit 200 is arranged to determine a mass flow MF of the predominant exhaust gases by means of a model. Here, for example, a predominant engine and engine load can be used by the model to determine a predominant MF mass flow of exhaust gases. The first control unit 200 is according to this modality arranged to calculate / model / estimate / determine a mass flow MF of the predominant exhaust gases without information from a mass flow sensor of the exhaust gases, such as sensor 247.

[0092] A first temperature sensor 241 is arranged for communication with the first control unit 200 through an L241 connection. The first temperature sensor 241 is arranged to measure a first predominant temperature T1 of the exhaust gases flowing in the first passage 255, upstream of the first SCR unit 260 and downstream of the engine 231. The first temperature sensor 241 is arranged to, continuously or intermittently, send signals S241 comprising information about the first predominant temperature T1 determined for the first control unit 200 through connection L241. The first control unit 200 is, according to one embodiment, arranged to determine a predominant temperature of the first SCR unit 260 based on the first detected temperature T1. The first control unit 200 is, according to this modality, arranged to calculate / model / estimate / determine a predominant temperature of the first SCR 260 unit.

[0093] A second temperature sensor 242 is arranged for communication with the first control unit 200 through an L242 connection. The first temperature sensor 242 is arranged to measure a second predominant temperature T2 of the exhaust gases flowing in the second passage 265, upstream of the second SCR unit 270 and downstream of the first SCR unit 260. The second temperature sensor 242 is arranged to continuously or intermittently send signals S242 comprising information about the second predominant temperature T2 determined for the first control unit 200 through connection L242. The first control unit 200 is, according to one embodiment, arranged to determine a predominant temperature of the second SCR unit 270 based on the second detected temperature T2. The first control unit 200 is, according to this modality, arranged to calculate / model / estimate / determine a predominant temperature of the second SCR unit 270.

[0094] A first NOx 251 sensor is arranged for communication with the first control unit 200 through an L251 connection. The first NOx 251 sensor is arranged to measure a predominant NOx value of NOxIN from the exhaust gases flowing in the first passage 255, upstream from the first SCR unit 260 and downstream from the engine 231. The first NOx sensor 251 is arranged to , continuously or intermittently, send signals S251 comprising information about the predominant NOx value determined NOxIN to the first control unit 200 through the L251 connection.

[0095] The first control unit 200 is, according to a modality, arranged to determine the predominant NOx value of NOxIN by means of a model. Here, for example, a predominant engine and the engine load can be used by the model to determine a predominant NOx NOx value. The first control unit 200 is, according to this modality, arranged to calculate / model / estimate / determine a predominant NOx value NOxIN without information from the first NOx sensor 251. The first control unit 200 is, according to this modality, arranged to calculate / model / estimate / determine a predominant NOx value of NOxIN in the first pass 255.

[0096] A second NOx 252 sensor is arranged for communication with the first control unit 200 through an L252 connection. The second NOx 252 sensor is arranged to measure a predominant NOx value of NOx1 from the exhaust gases flowing in the second passage 265, upstream of the second SCR unit 270 and downstream of the first SCR unit 260. The second NOx sensor 252 is arranged to continuously or intermittently send S252 signals comprising information on the predominant NOx value determined by NOx1 to the first control unit 200 via the L252 connection.

[0097] A third NOx 253 sensor is arranged for communication with the first control unit 200 through an L253 connection. The third NOx 253 sensor is arranged to measure a predominant NOx value of NOx2 from the exhaust gases flowing in the third passage 275 downstream of the second SCR 270 unit. The third NOx 253 sensor is arranged to, continuously or intermittently, sending S253 signals comprising information about the predominant NOx value determined by NOx2 to the first control unit 200 via the L253 link.

[0098] It can be noted that NOx sensors previously known in the art, and which can be used in the emission control arrangement as disclosed in this document, generally present a possible measurement error that depends on the value to be measured. A possible measurement error can, for example, be ± 10% of the value to be measured.

[0099] The first control unit 200 is arranged to determine a set of operational parameter values for the emission control arrangement. The set of operational parameter values is given by the determined mass flow MF of the exhaust gases, the temperature of the first SCR 260 unit, the temperature of the second SCR 270 unit and the NOx NOxIN value.

[0100] The first control unit 200 is arranged to determine a quantity of reducing agent for the first SCR 260 unit to obtain a content of

NOx predetermined downstream of the first SCR 260 unit. The first control unit 200 is arranged to determine a quantity of reducing agent for the first SCR 260 unit based on the determined set of operational parameter values. The first control unit 200 is arranged to dose reducing agent via the first dosage unit 237a to achieve the predetermined NOx content downstream of the first SCR 260 unit.

[0101] The first control unit 200 is arranged to determine an amount of reducing agent for the second SCR 270 unit to obtain a predetermined NOx content downstream of the second SCR 270 unit. The first control unit 200 is arranged to determine a quantity of reducing agent for the second SCR 270 unit based on the determined set of operational parameter values. The first control unit 200 is arranged to dose reducing agent via the second dosage unit 237b to achieve the predetermined NOx content downstream of the second SCR unit 270.

[0102] The first control unit 200 is arranged to determine a first degree of reduction of the NOx content for the first SCR 260 unit. The first control unit 200 is arranged to determine the first degree of reduction of the NOx content for the first SCR 260 unit based on the NOx NOxIN value in the first pass 255 and the NOx NOxl value of the exhaust gases flowing in the second pass 265. Hereby, the first degree of reduction of the NOx content is determined only in the first SCR 260 unit.

[0103] The first control unit 200 is arranged to determine a second degree of reduction of NOx content for the second SCR 270 unit. The first control unit 200 is arranged to determine a second degree of reduction of NOx content for second SCR unit 270 on the basis of the NOx NOxl value in the second passage 265 and the NOx NOx2 value of the exhaust gases flowing in the third passage 275. Hereby the second degree of reduction of the NOx content is determined only in the second SCR 270 unit.

[0104] The first control unit 200 is arranged to determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined. If, for example, the first degree of NOx content reduction is 90% and the second degree of NOx content reduction is 90%, the total degree of NOx content reduction for the emission control arrangement is 99 %, i.e. 100 (1- (1- 0.90) (1-0.90)) = 99%.

[0105] The first control unit 200 is arranged to compare the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement. The predetermined degree of reference for reducing the NOx content can be predetermined by observing engine emission regulations or engine emission laws. The value of the predetermined reference degree of NOx content reduction can be stored in the memory of the first control unit 200.

[0106] The first control unit 200 is arranged to determine that the emission control arrangement is operating as desired if the total degree of reduction of the NOx content exceeds the predetermined reference degree of reduction of the NOx content. If the degree of NOx content reduction exceeds the predetermined reference level of NOx content reduction, emission control is working as desired and in accordance with laws and regulations. Hereby, it is determined that the emission control arrangement is operating as desired, even if some of the first SCR 260 unit and the second SCR unit are not operating as desired, as the total degree of reduction in the NOx content is exceeding the predetermined reference degree of NOx content reduction.

[0107] According to one embodiment, the first control unit 200 is arranged to compare the first degree of NOx content reduction for the first SCR 260 unit with a first predetermined reference degree of NOx content reduction. In between, the first control unit 200 is further arranged to determine that the first SCR unit 260 is operating as desired if the first degree of NOx content reduction exceeds the first predetermined reference degree of NOx content reduction. The first unit control number 200 is arranged to generate an error code for the first SCR 260 unit if the first degree of NOx reduction does not exceed the first predetermined degree of NOx reduction. The value of the first predetermined reference degree NOx reduction system can be stored in the memory of the first control unit 200.

[0108] According to one embodiment, the first control unit 200 is arranged to compare the second degree of NOx content reduction for the second SCR configuration with a second predetermined degree of NOx content reduction. Hereby , the first control unit 200 is further arranged to determine that the second SCR 270 unit is operating as desired if the second degree of NOx reduction exceeds the second predetermined reference degree of NOx reduction. The first control unit control 200 is willing to generate an error code for the second SCR 270 unit if the second degree of NOx reduction does not exceed the second degree of predetermined reference NOx reduction. The value of the second predetermined degree of reference NOx NOx content reduction can be stored in the memory of the first control unit 200.

[0109] According to one modality, more than two SCR configurations (units) are arranged in series (see, for example, Fig. 2d-f) in the emission control arrangement. Hereby, the first control unit 200 is arranged to apply corresponding degrees of NOx reduction determination determinations to the emission control arrangement thus fully and individually extended. By this means, the first control unit 200 is arranged to determine the degrees of reduction of the NOx content for each of the SCR units arranged in series in the emission control arrangement. The first control unit 200 is arranged to determine a total degree of NOx content reduction for the emission control arrangement based on the NOx content reductions thus determined corresponding to each of the SCR units.

[0110] According to one modality, more than two SCR configurations (units) are arranged in series (see, for example, Fig. 2e-f) in the emission control arrangement, as well as at least one SCR unit in parallel. Hereby, the first control unit 200 is arranged to apply corresponding degrees of NOx reduction determination determinations to the emission control arrangement thus fully and individually extended. By this means, the first control unit 200 is arranged to determine the degrees of reduction of the NOx content for each of the SCR units arranged in series and in parallel in the emission control arrangement in an appropriate manner. The first control unit 200 is arranged to determine a total degree of NOx content reduction for the emission control arrangement based on the NOx content reductions thus determined corresponding to each of the SCR units. The inventive method is therefore applicable to various emission control arrangements with several SCR units.

[0111] The first control unit 200 is arranged to determine a degree of reduction of the NOx content for each of the SCR units of the emission control arrangement, to determine a total degree of reduction of the NOx content and to compare the total degree of reduction of NOx content with a predetermined degree of reduction of NOx content, and determine whether the emission control arrangement is operating as desired if the total degree of reduction of NOx content exceeds the predetermined degree of reduction of NOx NOx content.

[0112] Figure 2d schematically illustrates a configuration comprising N SCR units (SCR unit 1 - SCR unit N) being arranged in series downstream of a combustion engine (not shown), where N is a positive integer. Figure 2d illustrates schematically that the inventive method is applicable to any emission control arrangement comprising at least two SCR units being arranged in series. In this way, a degree of reduction of NOx content is determined for each of the SCR units (SCR unit 1 - SCR N unit). By using NOx sensors being arranged upstream and downstream of each SCR unit (SCR unit 1 - SCR N unit), the corresponding degrees of NOx content reduction can be determined. The supplied NOx sensors are arranged to detect the NOx content (NOxIN, NOx1, NOx2, ..., NOxN) upstream and downstream of each SCR unit (SCR unit 1 - SCR N unit).

[0113] A total degree of reduction of NOx content is determined based on the degrees of reduction of NOx content determined individually, whose total degree of reduction of NOx content is compared with a predetermined reference degree of reduction of NOx content , to determine whether the emission control arrangement is operating as desired or not.

[0114] According to one embodiment, there are fewer reducing agent dosage units than the SCR units in the emission control arrangement. This type of configuration can be applicable to all different emission control arrangements, according to one aspect of the invention. It is thus possible, for example, to supply a metering unit upstream of a first SCR unit being arranged first in a sequence of SCR units downstream of engine 231 and potentially one or more metering units upstream of other SCR units downstream of the first SCR unit. According to an exemplary embodiment in which the emission control arrangement comprises four SCR units arranged in series, a first metering unit is arranged upstream of a first SCR unit following the SCR unit and downstream of the 231. engine. the dosing unit is arranged upstream of a third SCR unit in the sequence of SCR unit and downstream of a second SCR unit in the sequence of SCR unit. Hereby, there is no dosage unit supplied upstream of the second SCR unit and a fourth SCR unit in the sequence of the SCR unit.

[0115] Figure 2e schematically illustrates a configuration comprising four SCR units (SCR unit 1a, SCR unit 1b, SCR unit 2a and SCR unit 2b) being arranged in parallel and in series downstream of a combustion engine (not shown). Figure 2e illustrates schematically that the inventive method is applicable to any emission control arrangement comprising two SCR units arranged in series and in parallel. Hereby, a degree of reduction of NOx content is determined for each of the SCR units. Using NOx sensors being arranged upstream and downstream of each SCR unit, the corresponding degrees of NOx content reduction can be determined. The NOx sensors provided are arranged to detect the NOx content (NOxIN1, NOx1a, NOx1b,

NOxIN2 NOx2a, NOx2b) upstream and downstream of each SCR unit. Hereby NOxIN1 and NOxIN2 represent about 50% of the initial NOx NOxIN content provided by the combustion engine.

[0116] A total degree of reduction of NOx content is determined based on the degrees of reduction of NOx content determined individually, whose total degree of reduction of NOx content is compared with a predetermined reference degree of reduction of NOx content , to determine whether the emission control arrangement is operating as desired or not.

[0117] Figure 2f schematically illustrates a configuration comprising three SCR units (SCR unit 1a, SCR unit 1b and SCR unit 2a), where the SCR unit 1a and the SCR unit 2a are being arranged in series downstream of an engine combustion (not shown) and the SCR 1b unit is arranged in parallel with the SCR 1a unit and in series with the SCR 2a unit. Figure 2f illustrates schematically that the inventive method is applicable to an emission control arrangement comprising more than two SCR units being arranged in series and in parallel. Hereby, a degree of reduction of NOx content is determined for each of the SCR units. Using NOx sensors being arranged upstream and downstream of each SCR unit, the corresponding degrees of NOx content reduction can be determined. The NOx sensors provided are arranged to detect the NOx content (NOxIN, NOx1a, NOx1b, NOxIN2 NOx2a) upstream and downstream of each SCR unit. Hereby, the NOx content being supplied to each of the SCR 1a and SCR 2a units is about 50% of the initial NOx NOxIN content being supplied by the combustion engine.

[0118] A total degree of reduction of NOx content is determined based on the degrees of reduction of NOx content determined individually, whose total degree of reduction of NOx content is compared with a predetermined reference degree of reduction of NOx content , to determine whether the emission control arrangement is operating as desired or not.

[0119] Hereby, a NOx NOxIN / 2 content and NOx NOx1a content downstream of the SCR 1a unit is used to determine a degree of reduction in the NOx content for the SCR 1b unit. Hereby, a NOx NOxIN / 2 content and the NOx NOx1b content downstream of the SCR 1b unit is used to determine a degree of reduction in the NOx content for the SCR 1b unit. Hereby, a NOx content (NOx1a + NOx1b) upstream of the SCR 2a unit and a NOx NOx2a content is used to determine a degree of reduction in the NOx content for the SCR 2a unit.

[0120] In some emission control arrangements, parallel SCR units are considered a unit in relation to NOx measurements. In this case, SCR units 1a and 1b can be considered as an SCR unit. Hereby, only a NOx sensor can be provided to measure the combined exhaust gas flows downstream of the SCR units 1a and 1b. In general, parallel SCR units are mainly provided for emission control arrangements due to space reasons. The inventive method is hereby adapted accordingly when it comes to determining the respective degrees of reduction of the NOx content for the SCR units of the emission control arrangement.

[0121] In light of the description in the previous paragraph, an alternative modality of the emission control arrangement described with reference to Figure 2e is available. In this embodiment, the passages downstream of the SCR unit 1a and SCR unit 1b are arranged so that the respective exhaust gas flows are combined. In this position, a single NOx sensor is arranged to measure the predominant NOx content. Downstream of this position, the passages are arranged to divide the flow of exhaust gases into substantially equal parts and conduct the respective flows of exhaust gases to the SCR 2a unit and the SCR 2b unit. Hereby, the two parallel SCR units SCR unit 1a and SCR unit 1b are considered as an SCR configuration and the two parallel SCR units unit SCR 2a and SCR unit 2b are considered as an SCR configuration. The inventive method is hereby adapted accordingly when it comes to determining the respective degrees of reduction of the NOx content for the SCR units of the emission control arrangement.

[0122] Figure 3 schematically illustrates a diagram in which a NOx NOx content is presented as a function of the P position of the emission control arrangement shown in Figure 2a or Figure 2c.

[0123] The NOx content axis is given in values of Log (10). A first interval P0 – P1 is provided here, which corresponds to the positions within the first passage 255, where the position P0 is directly downstream of the motor 231 and the position P1 is at an entrance of the first SCR 260 unit. second interval P1-P2, which corresponds to the positions within the second passage 265, where the position P1 is directly downstream of the first SCR unit 270 and the position P2 is at an entrance to the second SCR unit 270. A third interval is provided here P2-P3, which corresponds to the positions within the third pass 275, where position P2 is directly downstream of the second SCR unit 270 and position P3 is at the end of the third pass 275.

[0124] According to this example, the content of NOx NOxIN corresponding to the first interval P0-P1 is 1000 ppm. According to this example, the content of NOx NOx1 corresponding to the second interval P0-P1 is 10 ppm. According to this example, the content of NOx NOx2 corresponding to the third interval P0-P1 is 10 ppm. This means that the degree of NOx content reduction for the first SCR 260 unit is 90% and that the degree of NOx content reduction for the second SCR 270 unit is also 90%. The reduction in the total NOx content of the emission control arrangement is 99%.

[0125] In accordance with the invention and based on the emission control arrangement presented with reference to Figures 2a-2c, an example is given below. Example 1

[0126] It is assumed that the emission control arrangement is configured to achieve at least a 99% total NOx reduction. This is the predetermined reference degree of NOx content reduction. The first SCR 260 unit is controlled to achieve a 90% reduction in NOx and the second SCR 260 unit is controlled to achieve a 90% reduction in NOx. NOx.

[0127] NOxIN is measured to be 1,000 ppm.

[0128] ΝΟx1 is measured to be 100 ppm.

[0129] ΝΟx2 is measured to be 10 ppm.

[0130] Thus, the first degree of NOx content reduction for the first SCR 260 unit is determined to be 90% and the second degree of NOx content reduction for the second SCR 270 unit is determined to be 90% .

[0131] Hereby, the total degree of reduction of the NOx content for the emission control arrangement is determined to be 99%. This is done based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined. 100 (1- (1-0.90) (1-0.90)) = 99%

[0132] According to this example, it is determined that the emission control arrangement is operating as desired, since the total degree of reduction of the NOx content is not below the predetermined reference degree of reduction of the NOx content End of Example 1.

[0133] The corresponding calculations are performed for various emission control arrangements, in which the degrees of reduction of the NOx content determined individually are combined accordingly to form a total degree of reduction of the NOx content, which in turn is compared to a predetermined reference degree of NOx content reduction to determine whether the emission control arrangement is operating as desired or not.

[0134] Figure 4a schematically illustrates a flow chart of a method for diagnosing an emission control arrangement for a 231 combustion engine in operation, comprising at least a first SCR configuration and a second SCR configuration arranged in series.

[0135] The method comprises a first step s401 of the method. Step s401 of the method comprises the steps of: - determining a set of operational parameter values (MF, T1, T2, NOxIN) for the emission control arrangement; - determining and dosing a quantity of reducing agent for the first SCR configuration to obtain a predetermined NOx content downstream of the first SCR configuration;

- determining and dosing a quantity of reducing agent for the second SCR configuration to obtain a predetermined NOx content downstream of the second SCR configuration; - determine a first degree of reduction of NOx content for the first SCR configuration; - determine a second degree of reduction of NOx content for the second SCR configuration; - determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - compare the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - determine that the emission control arrangement is operating as desired if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction.

[0136] After step s401 of the method, the method ends / is returned.

[0137] Figure 4b schematically illustrates a method for diagnosing an emission control arrangement for a 231 combustion engine in operation, comprising a first SCR 260 configuration and a second SCR 270 configuration arranged in series. This modality refers to the emission control arrangement presented with reference to Figures 2a-2c.

[0138] The method comprises a first step s405 of the method. Step s405 of the method comprises the step of determining a set of operational parameter values for the emission control arrangement. Hereby, the predominant exhaust mass flow MF is determined by means of the exhaust gas flow sensor 247 and / or by the exhaust flow mass model. Hereby, the temperature of the first SCR unit 260 is determined by means of the first temperature sensor 241. Hereby, the temperature of the second SCR unit 270 is determined by means of the second temperature sensor 242. Hereby, the value NOx NOxIN is determined using the first NOx 251 sensor and / or the NOx content model.

[0139] After step s405 of the method, a subsequent step s410 of the method is performed.

[0140] Step s410 of the method comprises the step of determining and dosing a quantity of reducing agent for the first SCR 260 configuration to obtain a predetermined NOx content downstream of the first SCR 260 configuration. The quantity of reducing agent for the first configuration SCR 260 is determined based on the set of values of the operational parameters. The predetermined NOx content is determined based on the NOx NOxIN content. Alternatively, a dosage amount is dosed to obtain a predetermined degree of NOx content reduction for the first SCR 260 configuration. The amount of reducing agent for the first SCR 260 configuration is determined based on the set of operational parameter values. This is done using the first control unit 200. Dosing is carried out according to certain routines and based on the determined amount of reducing agent for the first SCR configuration

260. The first control unit 200 controls the operation of the first dosing unit 237a, in order to obtain the predetermined NOx content downstream of the first SCR 260 configuration.

[0141] After step s410 of the method, a subsequent step s415 of the method is performed.

[0142] Step s415 of the method comprises the step of determining and dosing a quantity of reducing agent for the second SCR 270 configuration to obtain a predetermined NOx content downstream of the second SCR 270 configuration. The quantity of reducing agent for the second configuration SCR 270 is determined based on the set of values of the operational parameters. The predetermined NOx content is determined based on the NOx NOx1 content. Alternatively, a dosage amount is dosed to obtain a predetermined degree of reduction of NOx content for the second SCR 270 configuration. This is done via the first control unit 200. Dosing is carried out according to certain routines and on the basis of in the determined amount of reducing agent for the second SCR 270 configuration. The first control unit 200 controls the operation of the second dosing unit 237b, in order to obtain the predetermined NOx content downstream of the second SCR 270 configuration.

[0143] After step s415 of the method, a subsequent step s420 of the method is performed.

[0144] Step s420 of the method comprises the step of determining a first degree of NOx content reduction for the first SCR 260 configuration. This is accomplished by the first 200 control unit. The first degree of NOx content reduction for the first SCR 260 configuration is calculated based on the NOx NOxIN content value (detected upstream of the SCR 260 configuration) and the NOx NOx1 content value (detected downstream from the SCR 260 configuration).

[0145] After step s420 of the method, a subsequent step s425 of the method is performed.

[0146] Step s425 of the method comprises the step of determining a second degree of reduction of NOx content for the second SCR 270 configuration. This is accomplished by the first control unit 200. The second degree of reduction of NOx content for the second SCR 270 configuration is calculated based on the NOx NOx1 content value (detected upstream of the SCR 270 configuration) and the NOx NOx2 content value (detected downstream from the SCR 270 configuration).

[0147] After step s425 of the method, a subsequent step s430 of the method is performed.

[0148] Step s430 of the method comprises the step of determining a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined. This is accomplished through the first control unit

200. Thus, a total degree of NOx content reduction for the emission control arrangement is determined based on the determined degrees of NOx content reduction of all SCR configurations in the emission control arrangement and, therefore, not only based on the NOx content values NOxIN and NOx2, that is, content values of ΝΟx upstream and downstream of all SCR configurations of the emission control arrangement.

[0149] After step s430 of the method, a subsequent step s435 of the method is performed.

[0150] Step s435 of the method comprises the step of comparing the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement. This is done through the first control unit 200. The predetermined degree of reference for reducing the NOx content for the emission control arrangement can be determined based on, for example, national / regional laws and regulations. The predetermined degree of reference for reducing the NOx content can be, for example, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99%.

[0151] Step s435 of the method may comprise the step of comparing the first degree of NOx reduction for the first SCR 260 configuration with a first predetermined reference degree of NOx reduction. This is accomplished through the first control unit 200. The first predetermined reference degree of NOx reduction for the first SCR 260 configuration can be determined based on, for example, national / regional laws and regulations or by a vehicle manufacturer 100. The first degree predetermined reference level for reducing the NOx content can be, for example, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99%.

[0152] Step s435 of the method can comprise the step of comparing s435 the second degree of NOx content reduction for the second SCR 270 configuration with a second predetermined degree of NOx content reduction. This is accomplished through first control unit 200. The second predetermined reference degree of NOx reduction for the second SCR 270 configuration can be determined based on, for example, national / regional laws and regulations or by a vehicle manufacturer 100. The second predetermined degree of reference for the reduction of NOx content can be, for example, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99%.

[0153] After step s435 of the method, a subsequent step s440 of the method is performed.

[0154] Step s440 of the method comprises the step of determining that the emission control arrangement is operating as desired, if the total degree of reduction of the NOx content exceeds the predetermined reference degree of reduction of the NOx content. total degree of NOx reduction is equal to or greater than the predetermined reference degree of NOx reduction, it is determined that the emission control arrangement is operating as desired. If the total degree of NOx reduction is below the predetermined reference degree of NOx reduction, it is determined that the emission control arrangement is not working as desired.

[0155] Step s440 of the method may comprise the step of determining that the first SCR 260 configuration is operating as desired if the first degree of NOx reduction is exceeding the first predetermined reference degree of NOx reduction and, if not, generate an error code for the first SCR 260 configuration.

[0156] Step s440 of the method may comprise the step of determining that the second SCR 270 configuration is operating as desired if the second degree of NOx reduction is exceeding the second predetermined reference degree of NOx reduction and, if not, generate an error code for the second SCR 270 configuration.

[0157] After step s440 of the method, the method is finalized / returned.

[0158] The inventive method is applicable to emission control arrangements, including additional SCR configurations in series and application of corresponding degrees of NOx reduction determinations for the emission control arrangement thus extended, fully and individually.

[0159] The inventive method is applicable to emission control arrangements, including additional SCR configurations in parallel and application of corresponding degrees of NOx reduction determinations for the emission control arrangement thus extended, fully and individually.

[0160] Figure 5 is a diagram of a version of a device 500. The control units 200 and 210 described with reference to Figure 2 may in one version comprise the device 500. The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read / write memory 550. Non-volatile memory 520 has a first memory element 530 in which a computer program, for example an operating system, is stored to control the function of the device 500. Device 500 further comprises a bus controller, a serial communication port, I / O means, an A / D converter, a time and date input and transfer unit, an event counter and an interrupt controller (no represented). Non-volatile memory 520 also has a second memory element 540.

[0161] The computer program P comprises routines to diagnose an emission control arrangement for a combustion engine in operation, comprising at least a first SCR configuration and a second SCR configuration arranged in series.

[0162] The computer program P can comprise routines to determine a set of operational parameter values for the emission control arrangement.

[0163] The computer program P can comprise routines for determining and dosing a quantity of reducing agent for the first SCR configuration to obtain a predetermined NOx content ΝΟx1 downstream of the first SCR configuration.

[0164] The computer program P may comprise routines for determining and dosing a quantity of reducing agent for the second SCR configuration to obtain a predetermined NOx content ΝΟx2 downstream of the second SCR configuration.

[0165] The computer program P can comprise routines to determine a first degree of reduction of NOx content for the first SCR configuration.

[0166] The computer program P can comprise routines to determine a second degree of reduction of NOx content for the second SCR configuration.

[0167] Computer program P may comprise routines to determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined.

[0168] The computer program P can comprise routines to compare the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement.

[0169] The computer program P can comprise routines to determine whether the emission control arrangement is operating as desired, if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction.

[0170] The computer program P can comprise routines to compare the first degree of NOx content reduction for the first SCR configuration with a predetermined first degree of NOx content reduction.

[0171] The computer program P can comprise routines to determine whether the first SCR configuration is operating as desired if the first degree of NOx reduction exceeds the first predetermined reference degree of NOx reduction and, if not, generate an error code for the first SCR configuration.

[0172] The computer program P can comprise routines for comparing the second degree of NOx content reduction for the second SCR configuration with a second predetermined degree of NOx content reduction.

[0173] Computer program P may comprise routines to determine that the second SCR configuration is operating as desired if the second degree of NOx reduction exceeds the second predetermined degree of NOx reduction and, if not, generate an error code for the second SCR configuration.

[0174] The computer program P can comprise routines for the application of corresponding degrees of NOx reduction determinations for a fully and individually extended emission control arrangement, in which additional SCR configurations have been included in the emission control arrangement. serial issues.

[0175] The computer program P can comprise routines for the application of corresponding degrees of NOx reduction determinations for a fully and individually extended emission control arrangement, in which additional SCR configurations have been included in the control control arrangement. parallel emissions.

[0176] The computer program P can comprise routines to perform any of the process steps detailed with reference to Figure 4b.

[0177] Program P can be stored in executable form or in compressed form in memory 560 and / or in read / write memory 550.

[0178] Where it is said that the data processing unit 510 performs a certain function, it means that it conducts a certain part of the program that is stored in memory 560 or a certain part of the program that is stored in read / write memory 550 .

[0179] 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. Separate memory 560 must communicate with the data processing unit over a data bus 511. Read / write memory 550 is arranged to communicate with data processing unit 510 over a data bus 514. Connections L210, L230, L231, L237a, L237b, L241, L242, L247, L251, L252 and L253, for example, can be connected to data port 599 (see Fig. 2a, 2b, 2c).

[0180] When data is received at data port 599, it is temporarily stored in the second memory element 540. When the incoming data received has been stored temporarily, data processing unit 510 will be ready to execute code execution as described above.

[0181] Parts of the methods described here can be conducted by the device

500 via the data processing unit 510 which executes the program stored in memory 560 or in read / write memory 550. When the device 500 executes the program, the method steps and the process steps described here are performed.

[0182] The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the invention to the variants described. Many modifications and variations will obviously be suggested to a person skilled in the art. The modalities were chosen and described to better explain the principles of the invention and its practical applications and, thus, enable a specialist in the art to understand the invention for different modalities and with the various modifications appropriate to the intended use.

[0183] The components and characteristics specified above can, within the framework of the invention, be combined between different specified modalities.

Claims (15)

1. Method for diagnosing an emission control arrangement for a combustion engine (231) in operation, the emission control arrangement comprising at least a first SCR configuration (260) and a second SCR configuration (270) arranged in series, the method characterized by the fact that it comprises the steps of: - determining (s405) a set of values of operational parameters for the emission control arrangement; - determining and dosing (s410) an amount of reducing agent for the first SCR configuration (260) to obtain a predetermined NOx content downstream of the first SCR configuration; - determining and dosing a quantity (s415) of reducing agent for the second SCR configuration (270) to obtain a predetermined NOx content downstream of the second SCR configuration; - determine (s420) a first degree of reduction of NOx content for the first SCR configuration (260); - determine (s425) a second degree of reduction of NOx content for the second SCR configuration (270); - determine (s430) a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - compare (s435) the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - determine (s440) that the emission control arrangement is operating as desired if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction. 2. Method, according to claim 1, characterized by the fact that it comprises the steps of: - comparing (s435) the first degree of reduction of NOx content for the first SCR configuration (260) with a first predetermined degree of reference reducing the NOx content; and - determine (s440) that the first SCR configuration (260) is operating as desired if the first degree of NOx content reduction exceeds the first predetermined reference degree of NOx content reduction and, if not, generate a code of error for the first SCR configuration (260). 3. Method, according to claim 1 or 2, characterized by the fact that it comprises the steps of: - comparing (s435) the second degree of reduction of NOx content for the second SCR configuration (270) with a second degree of predetermined reference for NOx content reduction; and - determine (s440) that the second SCR configuration (270) is operating as desired if the second degree of NOx reduction exceeds the predetermined second degree of NOx reduction reference and, if not, generate a error for the second SCR configuration (270). 4. Method according to any one of claims 1 to 3, characterized by the fact that it comprises the step of: - including in the emission control arrangement other SCR configurations in series and applying corresponding degrees of NOx reduction determinations for the emission control arrangement so fully and individually extended. 5. Method according to any one of claims 1 to 3, characterized by the fact that it comprises the step of: - including in the emission control arrangement other SCR configurations in parallel and applying corresponding degrees of NOx content reduction determinations for the emission control arrangement so fully and individually extended. 6. System for diagnosing an emission control arrangement for a combustion engine (231) in operation, the emission control arrangement comprising at least a first SCR configuration (260) and a second SCR configuration (270) arranged in series, the system characterized by the fact that it comprises: - means (200, 210, 500, 247, 241, 242, 251) arranged to determine a set of operational parameter values for the emission control arrangement; - means (200; 210; 500; 237a) arranged to determine and dose an amount of reducing agent for the first SCR configuration (260) to obtain a predetermined NOx content downstream of the first SCR configuration (260); - means (200; 210; 500; 237b) arranged to determine and dose an amount of reducing agent for the second SCR configuration (270) to obtain a predetermined NOx content downstream of the second SCR configuration (270); - means (200; 210; 500; 251, 252) arranged to determine a first degree of reduction of NOx content for the first SCR configuration (260); - means (200; 210; 500; 252, 253) arranged to determine a second degree of reduction of NOx content for the second SCR configuration; - means (200; 210; 500) arranged to determine a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction as well determined; - means (200; 210; 500) arranged to compare the total degree of reduction of NOx content for the emission control arrangement with a predetermined reference degree of reduction of NOx content for the emission control arrangement; and - means (200; 210; 500) arranged to determine that the emission control arrangement is operating as desired if the total degree of NOx content reduction exceeds the predetermined reference degree of NOx content reduction. 7. System according to claim 6, characterized by the fact that it comprises: - means (200; 210; 500) arranged to compare the first degree of NOx reduction for the first SCR configuration (260) with a first predetermined degree of reference for NOx content reduction; and - means (200; 210; 500) arranged to determine that the first SCR configuration (260) is operating as desired if the first degree of NOx content reduction exceeds the first predetermined reference degree of NOx content reduction and, if not, generate an error code for the first SCR configuration (260). 8. System according to claim 6 or 7, characterized by the fact that it comprises: - means (200; 210; 500) arranged to compare the second degree of reduction of NOx content for the second SCR configuration (270) with a second predetermined degree of reference for reducing the NOx content; and - means (200; 210; 500) arranged to determine that the second SCR configuration (270) is operating as desired if the second degree of NOx reduction exceeds the second predetermined degree of NOx reduction and, if not, generate an error code for the second SCR configuration (270). 9. System according to any one of claims 6 to 8, characterized in that it comprises: - other SCR configurations in series; and - means (200; 210; 500) to apply corresponding degrees of NOx reduction determination determinations to the emission control arrangement thus fully and individually extended. 10. System according to any one of claims 6 to 8, characterized by the fact that it comprises: - other SCR configurations in parallel; and - means (200; 210; 500) to apply corresponding degrees of NOx reduction determination determinations to the emission control arrangement thus fully and individually extended. 11. Vehicle (100; 110) characterized by the fact that it comprises a system as defined in any one of claims 6 to 10. 12. Vehicle (100; 110), according to claim 11, characterized by the fact that the vehicle is any one of a truck, bus or passenger car. 13. Computer program (P) to diagnose an emission control arrangement for an operating combustion engine, the emission control arrangement comprising at least a first SCR configuration (260) and a second SCR configuration (270) arranged in a series, in which the computer program (P) is characterized by the fact that it comprises program code to make an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500) perform the steps as defined in any of claims 1 to 5. 14. Computer program product characterized by the fact that it contains a program code stored on a computer-readable medium to perform the method steps as defined in any of claims 1 to 5, when the computer program is executed in a electronic control unit (200; 500) or on a computer (210; 500) connected to the electronic control unit (200; 500). 15. Method for diagnosing an emission control arrangement for a combustion engine (231) in operation, the emission control arrangement comprising at least a first SCR configuration (260) and a second SCR configuration (270) arranged in series, the method characterized by the fact that it comprises the steps of: - determining (s420) a first degree of reduction of the NOx content for the first SCR configuration (260); - determine (s425) a second degree of reduction of NOx content for the second SCR configuration (270); - determine (s430) a total degree of NOx content reduction for the emission control arrangement based on the first degree of NOx content reduction and the second degree of NOx content reduction so determined; - compare (s435) the total degree of reduction of the NOx content for the emission control arrangement with a predetermined reference degree of reduction of the NOx content for the emission control arrangement; and - determine (s440) that the emission control arrangement is operating as desired if the total degree of NOx reduction exceeds the predetermined reference degree of NOx reduction.