Exhaust aftertreatment device, exhaust tract with the exhaust aftertreatment device, internal combustion engine and device and method for controlling deposits

Abstract

The invention relates to an exhaust gas aftertreatment device (1000) for an exhaust tract (100), in particular of an internal combustion engine (50), comprising: - an exhaust gas guide (110) for the exhaust tract (100) for guiding exhaust gas (51), which is designed for a catalyst arrangement (200) for selectively catalyzing the exhaust gas (51) in the exhaust tract (100), wherein the exhaust gas guide (110) has a surface (101, 101'), - an imaging unit (90, 90') for imaging the surface, characterized by - a temperature detection unit (80, 80'), wherein - the temperature detection unit (80, 80') is formed by means of the imaging unit (90, 90'), wherein the temperature detection unit (80, 80') is designed to record a temperature profile with a temperature curve (400, 400') associated with the surface (101, 101'), and - a processing and evaluation device (70) which is designed to determine a change characteristic from the temperature profile (400, 400') and to indicate an assignment to a deposit (300) to a control unit (60) by means of the change characteristic.

Description

[0001] The invention relates to an exhaust gas aftertreatment device according to the preamble of claim 1 for an exhaust tract, in particular of an internal combustion engine. The invention also relates to an internal combustion engine, in particular an internal combustion engine, with an intake tract and an exhaust tract. The invention also relates to a device and a method for controlling deposits.

[0002] An above exhaust gas aftertreatment device for an exhaust tract, in particular of an internal combustion engine, comprises: - an exhaust gas guide of the exhaust tract, which is designed for a catalyst arrangement for the selective catalysis of an exhaust gas in the exhaust tract, wherein the exhaust gas guide has a surface and an imaging unit for imaging the surface.

[0003] In particular, the invention relates to an exhaust gas aftertreatment device for an exhaust tract of an internal combustion engine for improved detection, preferably also if necessary removal, of deposits, in particular urea deposits, within the exhaust tract of internal combustion engines with a catalyst arrangement for selective catalytic reduction (SCR).

[0004] Known processes for selective catalytic reduction aim to reduce nitrogen oxides in exhaust gases, including those from internal combustion engines. During the preferential reduction of nitrogen oxides such as NO and NO 2 Undesirable reactions such as the oxidation of the introduced reducing agent with atmospheric oxygen are largely avoided - therefore the reduction is referred to as selective. Typically, selective catalytic reduction requires ammonia NH 3which is added to the exhaust gas and reacts with the nitrogen oxides to form water H 2 O and nitrogen N 2 Reacts.

[0005] Known processes for selective catalytic reduction use urea as the starting material for selective catalytic reduction due to the ammonia it contains. However, in order for ammonia to be released from urea and used as a reducing agent for selective catalytic reduction, the urea must first be decomposed by a thermolysis reaction and a hydrolysis reaction. For this purpose, a so-called hydrolysis section is located in a section of the exhaust tract upstream of the actual catalyst in the direction of exhaust gas flow. In this hydrolysis section, the urea is injected into the exhaust stream in the form of an aqueous urea solution using an injector. During thermolysis, the urea is first decomposed into ammonia and isocyanic acid. In the subsequent hydrolysis, the isocyanic acid reacts with water to produce further ammonia and carbon dioxide.The released ammonia accumulates in the SCR catalyst and causes the nitrogen oxides to react to form water and nitrogen.

[0006] During the decomposition processes described, the temperature of the exhaust gas plays a role in the decomposition. Particularly at low exhaust temperatures, such as those that occur immediately after starting up an internal combustion engine, the decomposition of the urea may not be complete. In this case, the isocyanic acid formed as an intermediate product of thermolysis can form deposits on the inner walls of the exhaust tract. Such deposits are detrimental in several respects; in the worst case, they can lead to impairment or even blockage of the exhaust tract.

[0007] In the following, the term "deposit" is used to refer to deposits of all kinds, such as particulate deposits such as soot or the like, the term "reducing agent deposit" to refer to deposits of all types of reducing agents, and in particular "urea deposits" to refer to deposits of urea. In particular, "deposits" and "reducing agent deposits" also include deposits of intermediate products from the decomposition of urea or other reducing agents.

[0008] There are also known processes for removing urea deposits in exhaust tracts, in which the exhaust gas temperatures are increased by changing the operating parameters of a particular internal combustion engine in order to burn off the deposits. This process is subsequently referred to as a decrystallization cycle.

[0009] Furthermore, solutions for the removal of urea deposits in exhaust gas ducts are known from the prior art, which apply the described method for the combustion of urea deposits only in a time-dependent manner, such as after each expiration of a previously defined time interval, or in a load-dependent manner, such as after each travel of a previously defined number of kilometers.

[0010] The problem here is the inadequacy of a purely time- or load-dependent threshold as a trigger for the removal of urea deposits, which does not detect the actual presence of urea deposits in an exhaust system. Rather, the selective catalytic reduction processes are carried out "blindly" after certain criteria are met that indicate the potential presence of urea deposits.

[0011] US 2008 / 0 271 440 A1 discloses a method that determines the presence of urea deposits by measuring various parameters, such as the operating temperature of the SCR catalyst system, the exhaust gas pressure, or the pressure drop across the SCR catalyst system. Based on these parameters, the method initiates the described removal of the urea deposits by raising the exhaust gas temperature. In this method, a variety of parameters for removing urea deposits are evaluated. This approach also does not actually examine the exhaust system; instead, urea removal is initiated or not initiated based on the measurement of parameters related to urea deposits.

[0012] DE 10 2017 111 232 A1 discloses a method with a purely visual analysis of reducing agent deposits. This method provides an image acquisition unit in an exhaust system for detecting reducing agent deposits—for example, in the form of an image camera. An image processing unit is designed in such a way that reducing agent deposits can be visually detected as a surface feature in a recorded image of the exhaust system. However, the visual evaluation of an image captured by an image camera in the prior art also implies a complex and time-consuming data processing process due to the large amount of data to be evaluated.

[0013] DE 103 35 371 A1 describes a device for measuring the temperature of a catalyst through which exhaust gas from an internal combustion engine flows, comprising at least one image recording device. Its lens is directed, at least temporarily, at at least one measuring surface of the catalyst through which the exhaust gas flows. The device has an evaluation device by means of which a temperature profile of the at least one measuring surface can be created from at least one image sequence recorded by the at least one image recording device.

[0014] KR 10 2 131 500 B1 discloses an SCR system designed to prevent fire in an SCR catalyst by detecting and preventing deterioration of the SCR catalyst. A detection means is preferably a thermal imaging camera or an optical cable sensor, wherein the optical cable sensor is mounted on an SCR catalyst layer with a clamping device to detect deterioration locally without omission.

[0015] Faster and simpler monitoring, especially real-time monitoring, of urea deposits in an exhaust system with an SCR catalyst arrangement is desirable.

[0016] This is where the invention comes in, the object of which is to provide a device, a system, and a method for improved monitoring, in particular automatic real-time monitoring, of deposits. The object relates in particular to deposits in the form of reducing agent deposits, preferably in the form of urea deposits, in an exhaust system with an SCR catalyst arrangement.

[0017] The task is also to design the simplified data acquisition in this regard, in particular to design it in such a way that the amount of data and / or the effort required for data evaluation is reduced, in particular to provide an improved camera-based solution compared to a solution with an image camera, which is nevertheless reliable.

[0018] This object is achieved by an exhaust gas aftertreatment device according to claim 1.

[0019] Accordingly, the problem is solved by an exhaust gas aftertreatment device for an exhaust tract, in particular of an internal combustion engine. An exhaust gas duct—for guiding exhaust gas—of the exhaust tract is configured for a catalyst arrangement for selectively catalyzing the exhaust gas in the exhaust tract. The exhaust gas duct has a surface and an imaging unit for imaging the surface. Furthermore, the exhaust gas duct of the exhaust gas aftertreatment device has an imaging unit for imaging the surface and a processing and evaluation device.

[0020] According to the invention, the imaging unit is characterized by a temperature detection unit. The temperature detection unit is formed by the imaging unit and configured to record a temperature profile with a temperature gradient associated with the surface. The processing and evaluation device is further configured according to the invention to determine a change characteristic from the temperature gradient and, using the change characteristic, to indicate an assignment to a deposit to a control unit.

[0021] The invention is based on the consideration that real-time detection of urea deposits in an exhaust gas system by means of an image recording and image processing unit is effective, but that the complexity and time required for the evaluation can be significantly reduced by examining parameters whose evaluation has a positive effect on the amount of data to be processed and the associated complexity of the evaluation and control process.

[0022] The invention is based on the finding that deposits of all kinds, in particular reducing agent deposits, especially urea deposits, in an exhaust duct lead to the exhaust duct exhibiting a temperature radiation that differs from the surroundings of the deposit, at least on the surface of the deposit. In particular, the deposit or the exhaust duct may be significantly cooler, at least on the corresponding surface, than the surrounding wall of the exhaust duct. Deposits are thus clearly recognizable by correspondingly strong temperature differences. The invention therefore provides for the imaging unit to capture a temperature profile of the surface and to derive at least one temperature curve from this temperature profile.

[0023] The at least one temperature profile provides information about temperature differences on the surface in the exhaust system. Depending on the at least one temperature profile or the temperature differences contained in the at least one temperature profile, a change characteristic related to deposits is determined by means of the processing and evaluation device. The change characteristic can be a temperature gradient that indicates a strong local temperature difference in the exhaust system. Correspondingly large temperature gradients mean a rapid drop or rise in the respective temperature profile at transition points between a deposit-free surface and a deposit, and thus indicate the presence of urea deposits in the exhaust system.

[0024] This first aspect advantageously results in the possibility of real-time detection and on-demand removal of urea deposits with a reduced amount of data and a reduced data evaluation effort, since only the temperature curves recorded by the imaging unit need to be examined with regard to occurring temperature jumps.

[0025] Advantageous further developments of the invention can be found in the dependent claims and specify in detail advantageous possibilities for realizing the concept explained above within the scope of the task and with regard to further advantages.

[0026] In an advantageous development of the exhaust gas aftertreatment system, the processing and evaluation unit includes an image processing unit for processing the surface image from the temperature detection unit. This advantageously results in effective processing of the recorded surface image data.

[0027] In a further advantageous development of the exhaust gas aftertreatment system, the processing and evaluation unit is designed to use the change characteristic to indicate the assignment to the deposit to a control unit. This results in the possibility of transmitting corresponding data about a detected deposit in the exhaust tract to the control unit, so that the control unit can transmit corresponding control commands to an engine for removing the detected deposit, for example, to initiate a decrystallization cycle. Furthermore, assigning a change characteristic to a urea deposit specifically results in the advantage of requiring the removal of urea deposits. For example, it may also be the case that the change characteristic does not exceed a previously defined threshold value and removal of urea deposits is not necessary at this time.

[0028] In a further preferred embodiment of the exhaust gas aftertreatment device, the surface of the exhaust duct provided for imaging by the imaging unit is an inner surface of the exhaust duct. Using the inner surface advantageously results in a largely unadulterated measurement of the existing temperature profiles on the inner surface. In other words, the temperature differences are clearly visible on the inner surface.

[0029] Alternatively, it is also possible to record temperature profiles of an outer surface or another surface, in particular of the exhaust gas duct and / or the injector and / or a surface of the exhaust gas duct opposite the injector, by means of the imaging unit.

[0030] In an advantageous development, it is provided that the imaging unit is positioned with respect to the inner surface such that a guide region of the exhaust gas duct is located in the field of view of the imaging unit, in particular between the catalyst location and an injector location. The guide region extends in the flow direction of the exhaust gas upstream of the catalyst location for the catalyst arrangement in the exhaust gas duct. The guide region comprises those locations within the exhaust gas duct where the formation of deposits, in particular reducing agent deposits, is most likely. In addition, it is also conceivable to provide at least one imaging unit downstream of the catalyst in the exhaust gas duct in the flow direction of the exhaust gas.

[0031] In a further advantageous development, it is provided that the exhaust gas duct has an injector location for an injector, in particular an injector, preferably for injecting reducing agent into the exhaust gas duct.

[0032] Furthermore, within the scope of a further advantageous development, it is provided that the imaging unit is positioned with respect to the injector location for the injector such that the injector is located in the field of view of the imaging unit. Observing the injector and, if applicable, surfaces of the exhaust gas duct surrounding the injector using the imaging unit is particularly preferred, since deposits, in particular reducing agent deposits, are particularly likely at these locations. In particular, it is relevant for the function of the exhaust gas aftertreatment device to prevent the outlet opening of the injector from becoming clogged with deposits, in particular with reducing agent deposits. Therefore, the surface of the injector observed by the imaging unit is preferably a reducing agent outlet side of the injector.This offers the advantage of detecting injector clogging with deposits in real time and performing a decrystallization cycle accordingly, even if other surfaces of the exhaust tract do not yet show sufficient deposits for a decrystallization cycle. This always enables maximum efficiency of the exhaust aftertreatment system.

[0033] In an advantageous development, it is provided that the processing and evaluation device is designed to determine a change characteristic in the form of a temperature gradient of the temperature profile and / or in the form of a temperature plateau of the temperature profile from a temperature profile. The basis of the development is the finding that deposits, in particular urea deposits in an exhaust gas duct are significantly cooler than the surrounding wall of the exhaust gas duct. Urea deposits can therefore be clearly identified by corresponding strong temperature differences in the form of temperature gradients and in the form of lower temperature plateaus. This development is particularly advantageous with regard to reducing the amount of data to be evaluated to a temperature profile and corresponding temperature gradients and temperature plateaus.

[0034] A sharp temperature drop can be observed at the transitions from a deposit-free area of ​​a surface to a deposit, particularly a reducing agent deposit. This sharp temperature drop is accompanied by a correspondingly sharp temperature gradient. Conversely, a sharp temperature rise can be observed at the transition from a deposit to a deposit-free surface of the exhaust system. The temperature gradient represents a region of the temperature curve that has a changing temperature compared to the temperature of a surrounding region of the temperature curve.

[0035] The lower temperature of a deposit compared to the temperature of the surrounding deposit-free surface of the exhaust duct represents a lower temperature plateau in the temperature curve. The temperature plateau represents a region of the temperature curve that has a reduced and largely constant temperature compared to a temperature of an ambient region of the temperature curve.

[0036] Accordingly, pronounced temperature gradients and lower temperature plateaus represent deposits, particularly reducing agent deposits, in the exhaust gas system.

[0037] In a further advantageous development, the imaging unit is designed as an image acquisition unit to output an image data package associated with the surface in the form of a temperature map, wherein the temperature map contains the temperature profile with the temperature curve associated with the surface. The image acquisition unit enables rapid capture of the relevant temperature curve of the surface as the only required data set for the processing and evaluation unit.

[0038] The invention provides that the temperature profile assigned to the surface comprises a trajectory recorded along a location in the surface at a point in time and / or a transient recorded over time at a location on the surface.

[0039] As a result, the imaging unit, in particular the camera, only needs to evaluate the temperature profile along the exhaust duct or a section of the exhaust duct. This results in the advantage of a significantly smaller amount of data that must be evaluated by the image processing unit. Specifically, the invention offers the possibility of using a thermal camera as a camera, which is advantageous over an image camera.

[0040] In the invention, the trajectory has a gradient that can be assigned to an edge of the deposit and / or the transient to a time of deposit formation. This advantageously results in the possibility of improved spatial and temporal assignment of gradients and urea deposits.

[0041] In a preferred embodiment, the control unit is configured to indicate a control measure for exhaust gas aftertreatment in the exhaust tract that is suitable for removing the deposit. This provides a rapid and needs-based option for removing urea deposits by removing a urea deposit previously detected based on temperature gradients and / or temperature plateaus by the control unit by changing the operating parameters of the internal combustion engine.

[0042] Furthermore, in combination with the real-time-based measurement of the temperature profiles and the removal of reducing agent deposits by changing the operating parameters of the internal combustion engine, it is advantageously possible for the control unit to indicate that the urea deposits have been removed by detecting a drop in the temperature gradients and / or temperature plateaus to a previously defined threshold value or a complete disappearance of the temperature gradients and / or temperature plateaus, so that the operating parameters of the internal combustion engine changed to remove the urea deposits are returned to their initial state.

[0043] Furthermore, the invention relates to an exhaust tract according to claim 11 and an internal combustion engine according to claim 13 as well as a device according to claim 14 for controlling deposits.

[0044] In this respect, the object is achieved in a further aspect by an exhaust tract for an internal combustion engine with an exhaust gas aftertreatment device, comprising a catalyst arrangement (SCR catalyst arrangement) with an SCR catalyst for the selective catalysis of an exhaust gas in the exhaust gas duct.

[0045] Furthermore, the invention relates to an internal combustion engine, in particular an internal combustion engine, having an intake tract and an exhaust tract, and an engine control device. In this respect, the object is achieved in a further aspect by an internal combustion engine, in particular an internal combustion engine, having an intake tract and an exhaust tract, and by a control unit for initiating a control measure for exhaust gas aftertreatment for the exhaust tract, which is suitable for removing the deposits.

[0046] Furthermore, the invention relates to a device for controlling deposits, in particular reducing agent deposits. In a further aspect, the object is achieved by a device for controlling deposits, in particular reducing agent deposits, in an exhaust tract comprising an exhaust duct, an SCR catalyst arrangement, and an imaging unit for imaging the surface of the exhaust duct, in particular for an exhaust aftertreatment device.

[0047] The device further comprises an imaging unit for imaging the surface of the exhaust duct. The imaging unit comprises a temperature detection unit. The temperature detection unit is formed by the imaging unit and is configured to record a temperature profile with a temperature gradient associated with the surface. Furthermore, the device comprises a processing and evaluation unit configured to determine a change characteristic from the temperature gradient and, using the change characteristic, to indicate an assignment to a deposit to a control unit.

[0048] Furthermore, the invention relates to a method according to claim 15 for controlling deposits, in particular reducing agent deposits, in an exhaust tract, in particular with an SCR catalyst arrangement and with an imaging unit for imaging a surface of an exhaust gas duct of the exhaust tract, in particular for an exhaust gas aftertreatment device, wherein the method represents a further aspect for solving the problem.

[0049] In the process, the surface is imaged, a temperature profile is recorded with a temperature gradient associated with the surface, and a change characteristic is determined from the temperature gradient. Using the change characteristic, an assignment to a deposit is displayed to a control unit.

[0050] Embodiments of the invention will now be described below with reference to the drawings in comparison to the prior art, some of which is also shown. These are not necessarily intended to show the embodiments to scale; rather, the drawings are designed in a schematic and / or slightly distorted form for explanatory purposes only. With regard to additions to the teachings immediately apparent from the drawings, reference is made to the relevant prior art. It should be noted that many modifications and changes to the form and detail of an embodiment can be made without departing from the general idea of ​​the invention. The features of the invention disclosed in the description, the drawings and the claims can be essential for further developing the invention, both individually and in any combination.Furthermore, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of ​​the invention is not limited to the exact form or detail of the preferred embodiment shown and described below, or limited to an object that would be limited compared to the object claimed in the claims. In the case of specified dimensioning ranges, values ​​lying within the stated limits are also intended to be disclosed as limit values ​​and to be used and claimed as desired. Further advantages, features and details of the invention emerge from the following description of the preferred embodiments and from the drawings, which show in:. Fig. 1: schematically shows an embodiment of an exhaust gas aftertreatment device with an exhaust tract and thermal camera with a processing and evaluation device; Fig. 2: a preferred alternative arrangement of a plurality of cameras of an exhaust aftertreatment device around the circumference of an exhaust tract; Fig. 3: a schematic representation of the exhaust gas aftertreatment device to explain a method for controlling deposits, in particular for real-time detection of urea deposits, Fig. 4: schematically an explanatory example of a temperature map of the surface (a) and an example of a temperature curve on a line of the temperature map (b), Fig. 5: schematically a vehicle with an exhaust tract and with the exhaust aftertreatment device and a control system.

[0051] The schematic embodiment shown in Fig. The system of an exhaust gas aftertreatment device 1000 for an exhaust tract 100 of an internal combustion engine 50 shown in Figure 1 is designed for the detection and, in the present case, in particular for the removal of Fig. 3 and Fig. 4 deposits shown in more detail 300 (in Fig. 1 not shown), namely in this case in particular urea deposits 310, as well as deposits of intermediate products from the decomposition of urea or other reducing agents in an exhaust tract 100 of an internal combustion engine 50. In the embodiment in Fig. 1, the exhaust tract 100 comprises an SCR catalyst 200 of the internal combustion engine 50 and an injector 40 for injecting a reducing agent into the exhaust tract 100. The exhaust duct 110 of the exhaust tract 100 has a surface 101. An imaging unit 90 is arranged such that the surface 101 is positioned in the field of view of the imaging unit 90. The imaging unit 90 comprises a temperature detection unit 80 and is communicatively connected to a processing and evaluation device 70 and a control unit 60. The processing and evaluation device 70 comprises an image processing unit 75 for processing the images of the surface 101, 101' transmitted by the imaging unit 90. The processing and evaluation device 70 is communicatively connected to the control unit 60 so that change characteristics can be transferred to the control unit 60 by the processing and evaluation device 70.The control unit 60 is designed to transmit control commands to the internal combustion engine 50 in accordance with the change characteristics transmitted to it, so that a decrystallization cycle for removing detected deposits 300, in particular urea deposits 310, can be initiated.

[0052] Preferably, the imaging unit 90 is designed to measure temperatures by means of the temperature detection unit 80 and is, for example, in the form of a thermal camera. Alternatively, an arrangement of one or more thermal sensors is also possible. For example, at least two thermal sensors can be used to record the temperatures. The term "camera" is used below for thermal cameras or arrangements of at least one thermal sensor. Preferably, the camera of the imaging unit 90 is integrated into the wall of the exhaust tract 100 such that the imaging unit—hereinafter also referred to as camera 90—is directed directly at the surface 101. This enables the temperatures prevailing on the surface 101 to be recorded with minimal attenuation, or the signals to be recorded are at their strongest.Furthermore, the exhaust tract 100 of the exhaust aftertreatment device 1000 can have an additional imaging unit 90' with an additional temperature detection unit 80'. The additional imaging unit 90' is mounted in the wall of the exhaust tract 100 such that the injector 40 is located in the field of view of the additional imaging unit 90'. The additional imaging unit 90' is directed towards the injector 40, in particular towards a surface 101' of the injector 40. The surface 101' is preferably a reducing agent outlet side of the injector 40. As a result, the additional imaging unit 90' can detect urea deposits 310 on the injector 40 and in particular at the outlet opening of the injector 40 in real time. The additional imaging unit 90' is communicatively connected to the processing and evaluation device 70 and the control unit.Preferably, the injector 40 is introduced into the wall of the exhaust tract 100 in such a way that the reducing agent outlet side 101' of the injector 40 forms a flush transition to the wall of the exhaust tract 100 and the injector 40 does not or substantially does not protrude into the exhaust tract 100.

[0053] Preferably, the surface 101 is an inner surface 102 of the exhaust duct 110 of the exhaust system 100. Alternatively, the camera 90 can be arranged in an external environment of the exhaust system 100. In this arrangement, the camera 90 is directed at an outer surface of the exhaust system 100 and records the temperatures of the outer surface. In a further alternative embodiment, it is also possible for at least two cameras 90 to be arranged around the circumference of the exhaust system 100 or the exhaust duct 110.

[0054] For the sake of simplicity and clarity, the same reference symbols are used below for the same or similar features or features with the same or similar function.

[0055] This shows Fig. 2 shows a schematic embodiment in which three cameras 90 are arranged equidistantly around the circumference of the exhaust tract 100, each camera 90 being aligned with an inner surface 101 of the exhaust tract 100 opposite the respective camera 90. This enables improved detection of urea deposits 310. It is also conceivable that at least two cameras 90 are arranged at at least two different locations around the circumference of the exhaust duct 110.

[0056] Furthermore, within the scope of a further embodiment, it is conceivable that, in addition to the imaging units 90 and 90' arranged upstream of the catalytic converter 200 in the flow direction 52 of the exhaust gas, at least one further imaging unit 90 is arranged downstream of the catalytic converter 200 in the flow direction 52 of the exhaust gas in order to detect reducing agent deposits 311, in particular urea deposits 310, behind the catalytic converter 200. Any combinations of the alternative embodiments are also possible. In particular, combinations of a number of cameras 90 with a wide variety of positioning are possible. For example, an arrangement of a number of cameras 90 along a length and / or a circumference of the exhaust tract is possible.These variants can also be implemented in combination with a positioning of cameras 90 upstream or downstream of the SCR catalyst 200 in the flow direction 52 of the exhaust gas within the scope of advantageous further embodiments not shown here. In principle, within the scope of advantageous embodiments, it is conceivable that any surfaces 101 on or in the exhaust tract 100 are observed by imaging units 90 wherever a person skilled in the art has reason to believe that these surfaces 101 are particularly susceptible to the formation of deposits 300 or urea deposits 310 or reducing agent deposits 311.

[0057] Fig. 3 schematically illustrates the concept of the invention, explaining a method for real-time detection of urea deposits 310 by temperature gradients 410 with reference to the exhaust gas aftertreatment device 1000 for an exhaust tract 100 of an internal combustion engine 50 with an imaging unit 90.

[0058] The imaging unit 90 is designed to measure temperatures, in particular temperatures of the surface 101, 102, by means of a temperature detection unit 80 and to transmit the temperature data to a processing and evaluation device 70 with an image processing unit 75.

[0059] The transmitted temperature data can contain a temperature profile 400 across the entire recorded surface 101, 102. It is also preferably conceivable that only partial areas of the temperature recording, such as individual lines, from the temperature profile 400 of the temperature recording of the surface 101, 102 are transmitted to the processing and evaluation device 70 in order to further minimize the data processing effort. The processing and evaluation device 70 is configured to derive temperature gradients 410 and / or temperature plateaus 420 and, if necessary, further data from the transmitted temperature data using the image processing unit 75.

[0060] In the present case, based on Fig. 3 primarily explains that the temperature profile 400 of the temperature T assigned to the surface 101, 102 is a trajectory T(s) recorded along a spatial profile s in the surface 101, 102 at a time t. This results in the possibility of further reducing the amount of data to be processed. By recording a trajectory T(s) of the temperature profile 400 over the spatial profile s, an evaluation of individual images of the trajectory T(s) of the surface 101, 102 at a respective time is possible. Time intervals between the individual images - recording intervals - can be adapted to the probability of the formation of deposits 300 or urea deposits 310. For example, the recording intervals can be selected to be large after the removal of deposits 300 or urea deposits 310. As soon as the individual images show the first signs of change characteristics, e.g.in the form of first small detectable temperature gradients 410 or first small temperature plateaus 420, the recording intervals can be successively reduced in order to monitor the change in the deposits 300 or urea deposits 310 more closely and to initiate removal of the deposits 300, in particular urea deposits 310, when certain predefined values ​​or a previously definable number of deposits 300, in particular urea deposits 310, are exceeded. As a result, the amount of data to be processed is variably adapted to the presence of deposits 300 or urea deposits 310.

[0061] In the present case, the scheme primarily explains the concept using temperature gradients 410 of the trajectory T(s) with associated position data as an example - the possibility of evaluating a time course T(t) in this regard is also indicated.

[0062] Alternatively, the temperature profile 400 of the temperature T assigned to the surface 101, 102 can include a transient; the transient represents a time profile T(t) of a temperature recorded at a location s of the surface 101, 102. This advantageously results in an investigation of the temperatures of the temperature profile 400 in real time and the possibility of faster detection of emerging temperature gradients 410.

[0063] Referring to Fig. 3 concerning the trajectory T(s), it can be seen that a clear temperature drop can be detected at the transitions from a surface of a wall of the exhaust tract 100 that is free of urea deposits 310 to a urea deposit 310. At the transition points, the respective locally corresponding temperature gradients 410, which indicate the gradient of the temperature profile 400 at the transition points, are correspondingly pronounced. These particularly pronounced temperature gradients 410 are recognized by the processing and evaluation device 70 as a change characteristic and confirm the presence of deposits 300 or urea deposits 310 in the exhaust tract 100.

[0064] In the schematic embodiment in Fig. 3 shows, by way of example, a temperature profile 400 of a surface 101, 102 of the exhaust gas guide 110 of the exhaust tract 100 in the flow direction 52 of the exhaust gas upstream of the SCR catalyst 200. Fig. 3 urea deposits 310 corresponding to the temperature profile 400. The temperature profile 400 recorded by the imaging unit 90 by means of the temperature detection unit 80 and transmitted to the processing and evaluation device 70 with the image processing unit 75 is also shown in the Fig. 3. The temperature profile 400 drops noticeably across the urea deposits 310 and forms lower temperature plateaus 420 across the width of the urea deposit 310, rising again to a relatively constant and higher temperature range at locations on the surface 101, 102 of the exhaust tract 100 without urea deposits 310. The locations at which the temperature profile 400 drops sharply correspond to correspondingly pronounced temperature gradients 410. For this reason, the data to be evaluated by the processing and evaluation device 70 with the image processing unit 75 can be reduced to merely the profile of the temperature gradients 410.The processing and evaluation device 70 evaluates the image data transmitted to it by the imaging unit 90 with regard to change characteristics and transmits data to the control unit 60 so that the latter can transmit corresponding control commands for removing detected urea deposits 310 to an internal combustion engine 50.

[0065] Fig. Figure 4 illustrates in view a) in a schematic embodiment a temperature map 500 - as it could be recorded, for example, by the camera 90 - of the surface 101, 101', 102 with a urea deposit 310. Dark areas indicate high temperatures and light areas indicate lower temperatures. The urea deposit 310 is clearly recognizable by an abrupt drop in temperatures across the urea deposit 310. Furthermore, Fig. 4 in view a) it can be seen that just one line Z of this temperature map 500 is sufficient to detect the urea deposit 310.

[0066] For example, it is also conceivable that only every second line is evaluated by the processing and evaluation device 70 in order to ensure sufficient coverage of the surface 101, 101', 102. Furthermore, it is conceivable that different lines of the temperature map 500 are evaluated by the processing and evaluation device 70 in an alternating rhythm in order to keep the data evaluation effort low and at the same time be able to evaluate the entire surface 101, 101', 102.

[0067] Fig. 4 illustrates in view b) in a schematic embodiment the temperature profile 400 of the row Z from the temperature map 500 and the associated profile of the temperature gradients 410 from the temperature map 500 in Fig. 4 a). The sudden temperature drop at the transition point between the deposit-free surface 101, 101', 102 and the urea deposit 310, or the sudden temperature increase at the transition from the urea deposit 310 to the deposit-free surface 101, 101', 102, corresponds to strongly pronounced temperature gradients 410, which are recognized by the processing and evaluation device 70 as a change characteristic and indicate a urea deposit 310.

[0068] Furthermore, the processing and evaluation device 70 is configured to assign locally corresponding urea deposits 310 in the exhaust tract 100 to the temperature gradient 410 and any additional data. Furthermore, the processing and evaluation device 70 is configured to transmit information to the control unit 60.

[0069] The control unit 60 is configured to transmit control commands to the internal combustion engine 50 in order to change the operating parameters of the internal combustion engine 50. The change in the operating parameters of the internal combustion engine 50 aims at increasing the exhaust gas temperature of the exhaust gas 51, which can lead to the removal of the urea deposits 310 in the exhaust tract 100.

[0070] Threshold values ​​for the temperature gradients 410 are preferably adjustable, so that there is a limit that can be defined and quantified by a user. If exceeded, the processing and evaluation device 70 forwards corresponding information to the control unit 60 so that the control unit 60 transmits corresponding control commands to the internal combustion engine 50 to trigger a decrystallization cycle. Examples of such threshold values ​​can be percentages of the higher ambient temperature around a urea deposit 310. For example, a threshold value can be exceeded if the evaluation unit 70 determines that at a point of the temperature recording of the surface 101, 101', 102, a local temperature drops by more than 10% of an average temperature value—which represents the temperature level of the wall of the exhaust tract 100.Another exemplary, user-definable threshold for triggering a decrystallization cycle can be the number of detected urea deposits 310. Another exemplary, user-definable threshold can be the size of the detected urea deposit 310. Combinations of these exemplary thresholds can also be defined by a user as thresholds for triggering a decrystallization cycle. For example, a decrystallization cycle can be triggered by the control unit 60 when a specified minimum number of urea deposits 310 are detected or when—regardless of the total number of detected urea deposits 310—at least one urea deposit 310 with a previously defined minimum diameter is detected.

[0071] Fig.5 shows a schematic embodiment of a motor vehicle 2000 including an internal combustion engine 50 and an exhaust gas aftertreatment device 1000. The exhaust gas aftertreatment device 1000 can be used in vehicles with an SCR catalyst arrangement. Furthermore, vehicles can be retrofitted with the exhaust gas aftertreatment device 1000.

[0072] Furthermore, it is conceivable that the exhaust gas aftertreatment device 1000 is used in stationary systems or mobile systems that utilize an internal combustion engine 50, in particular an internal combustion engine, with an intake tract and an exhaust tract 100 and an SCR catalyst arrangement. The aforementioned exhaust gas aftertreatment for the exhaust tract 100, which is designed to remove a deposit 300, can also be advantageously used therein according to the concept of the invention. In particular, it can be retrofitted to such existing stationary systems or mobile systems. Examples of such stationary systems are gensets or similar containers for energy supply. Furnaces, waste incineration plants, and gas turbines are also suitable.Examples of such mobile systems include not only internal combustion engines 50 in ships or floating units, but also internal combustion engines 50 in commercial or military vehicles in general. In particular, an application of the exhaust gas aftertreatment device according to the concept of the invention for an internal combustion engine 50 in a rail vehicle is appropriate, especially since an SCR catalyst arrangement has become established in rail vehicle drives with an internal combustion engine alone or as part of a genset. LIST OF REFERENCE SYMBOLS 40 Injector 50 internal combustion engine 51 exhaust 52 Flow direction of the exhaust gas 60 control unit 70 Processing and evaluation device 75 Image processing unit 80 temperature recording unit 80' additional temperature recording unit 90 imaging unit, camera 90' additional imaging unit, camera 100 exhaust tract 101 Surface of the exhaust system 101' Injector surface 102 Inner surface of the exhaust system 110 Exhaust system 200 SCR catalyst 300 deposits 310 Urea deposits 311 Reducing agent deposit 400 Temperature profile over the surface 400' temperature curve over the surface of the injector 410 Temperature gradient 420 temperature plateau 500 temperature map 1000 exhaust aftertreatment device 2000 vehicle with exhaust aftertreatment system T Temperature T(Z) temperature curve T(s) trajectory of temperature T(t) Time course of temperature Z line of a thermal image

Claims

[1] Exhaust gas aftertreatment device (1000) for an exhaust tract (100), in particular of an internal combustion engine (50), comprising: - an exhaust gas guide (110) for the exhaust tract (100) for guiding exhaust gas (51), which is designed for a catalyst arrangement (200) for selectively catalyzing the exhaust gas (51) in the exhaust tract (100), wherein the exhaust gas guide (110) has a surface (101, 101'), - an imaging unit (90, 90') for imaging the surface, - a temperature detection unit (80, 80'), wherein - the temperature detection unit (80, 80') is formed by means of the imaging unit (90, 90'), characterized by , that - the temperature detection unit (80, 80') is designed to record a temperature profile with a temperature profile (400, 400') associated with the surface (101, 101'), wherein the temperature profile (400, 400') associated with the surface (101, 101') comprises a trajectory (T(s)) recorded along a location in the surface (101, 101') at a time (t) and / or a time profile of a transient (T(t)) recorded at a location (s) of the surface (101, 101'), and the trajectory (T(s)) has a temperature gradient (410) associated with an edge of the deposit (300) and / or the transient (T(t)) has a temperature gradient (410) associated with a time of formation of the deposit (300), and - a processing and evaluation device (70) which is designed to determine a change characteristic from the temperature profile (400, 400') and to indicate an assignment to a deposit (300) to a control unit (60) by means of the change characteristic. [2] Exhaust gas aftertreatment device (1000) according to claim 1, characterized bythat the processing and evaluation device (70) has an image processing unit (75) for processing the image of the surface (101, 101') from the temperature detection unit (80, 80'). [3] Exhaust gas aftertreatment device (1000) according to claim 1 or 2, characterized by that the processing and evaluation device (70) is designed to indicate to a control unit (60) an assignment to the deposit (300), in the form of a reducing agent deposit (311), preferably in the form of a urea deposit (310), by means of the change feature. [4] Exhaust gas aftertreatment device (1000) according to one of the preceding claims, characterized by that the surface (101) provided for imaging by the imaging unit (90) is an inner surface (102) of the exhaust gas duct (110). [5] Exhaust gas aftertreatment device (1000) according to one of the preceding claims, characterized bythat the imaging unit (90) is positioned with respect to the inner surface (102) in such a way that a guide region of the exhaust gas guide (110), in the flow direction (52) of the exhaust gas (51) in front of a catalyst location for the catalyst arrangement (200) in the exhaust gas guide (110), is located in the field of view of the imaging unit (90), in particular between the catalyst location and an injector location. [6] Exhaust gas aftertreatment device (1000) according to one of the preceding claims, characterized by that the exhaust gas duct (110) has an injector location for an injector (40), in particular an injector (40) for injecting reducing agent into the exhaust gas duct (110). [7] The exhaust aftertreatment device (1000) of claim 6, wherein the imaging unit (90') is positioned with respect to the injector location for the injector (40) such that the injector (40) is located in the field of view of the imaging unit (90'). [8] Exhaust gas aftertreatment device (1000) according to one of the preceding claims, in which the processing and evaluation device (70) is designed to determine from the temperature profile (400, 400') - the change feature in the form of the temperature gradient (410) of the temperature profile (400), and / or - to determine the change characteristic in the form of a temperature plateau (420) of the temperature curve (400, 400'). [9] Exhaust gas aftertreatment device (1000) according to one of the preceding claims, characterized by that the imaging unit (90) is designed as an image recording unit in order to output an image data packet assigned to the surface (101) in the form of a temperature map (500), wherein the temperature map (500) contains the temperature profile with the temperature curve (400) assigned to the surface (101). [10] Exhaust gas aftertreatment device (1000) according to one of the preceding claims, characterized bythat the control unit (60) is designed to indicate a control measure for exhaust gas aftertreatment for the exhaust tract (100) which is suitable for removing the deposit (300). [11] Exhaust tract (100), in particular for an internal combustion engine (50), with an exhaust aftertreatment device (1000) according to one of claims 1 to 10, with a catalyst arrangement designed for the selective catalysis of an exhaust gas (51) in the exhaust duct (110). [12] Exhaust tract (100) according to claim 11, wherein the catalyst arrangement comprises an SCR catalyst (200) designed for the selective catalysis of an exhaust gas (51) in the exhaust tract (100). [13] Internal combustion engine (50), in particular an internal combustion engine, with an intake tract and an exhaust tract (100) according to claim 11 or 12 and with a control unit (60) for controlling a control measure for exhaust gas aftertreatment for the exhaust tract (100), which is designed to remove a deposit (300). [14] Device for controlling deposits (300), in particular reducing agent deposits (311), in an exhaust tract (100), in particular with an SCR catalyst (200), with an imaging unit (90, 90') for imaging a surface (101, 101') of an exhaust gas duct (110), in particular for an exhaust gas aftertreatment device (1000) according to one of claims 1 to 10, wherein the device further comprises: - an imaging unit (90, 90') for imaging the surface of the exhaust gas duct (110), - a temperature detection unit (80, 80'), wherein - the temperature detection unit (80, 80') is formed by means of the imaging unit (90, 90'), characterized by , that - the temperature detection unit (80, 80') is designed to record a temperature profile with a temperature profile (400, 400') associated with the surface (101, 101'), wherein the temperature profile (400, 400') associated with the surface (101, 101') comprises a trajectory (T(s)) recorded along a location in the surface (101, 101') at a time (t) and / or a time profile of a transient (T(t)) recorded at a location (s) of the surface (101, 101'), and the trajectory (T(s)) has a temperature gradient (410) associated with an edge of the deposit (300) and / or the transient (T(t)) has a temperature gradient (410) associated with a time of formation of the deposit (300), and - a processing and evaluation device (70) with an image processing unit (75) which is designed to determine a change feature from the temperature profile (400, 400') and to indicate an assignment to a deposit (300) to a control unit (60) by means of the change feature. [15] Method for controlling deposits (300), in particular reducing agent deposits (311), in an exhaust tract (100), in particular with an SCR catalyst (200), with an imaging unit (90, 90') for imaging a surface (101, 101') of an exhaust gas duct (110), in particular for an exhaust gas aftertreatment device (1000) according to one of the preceding claims 1 to 10, wherein in the method: - the surface (101, 101') is imaged, characterized by , that - a temperature profile is recorded with a temperature profile (400, 400') associated with the surface (101, 101'), wherein the temperature profile (400, 400') associated with the surface (101, 101') comprises a trajectory (T(s)) recorded along a location in the surface (101, 101') at a time (t) and / or a time profile of a transient (T(t)) recorded at a location (s) of the surface (101, 101'), and the trajectory (T(s)) has a temperature gradient (410) associated with an edge of the deposit (300) and / or the transient (T(t)) has a temperature gradient (410) associated with a time of formation of the deposit (300), and - a change characteristic is determined from the temperature profile (400, 400') by a processing and evaluation device (70) with an image processing device (75), - by means of the change feature, an assignment to a deposit (300) is displayed to a control unit (60).

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