DE102017111232A1 - Method for real-time detection of deposits in internal combustion engines with AGN systems - Google Patents

Abstract

The invention relates to a device (10) for detecting deposits in an exhaust gas tract of an internal combustion engine. The device (19) has an exhaust pipe (12) and an image pickup unit (16) arranged to receive a surface (12A, 24A) provided in the exhaust pipe (12). The image pickup unit (16) is adapted to capture and output a photograph of the surface (12A, 24A). An image processing unit (18) is adapted to receive the image and process it for inspection on a deposit located on the surface (12A; 24A).

Description

The invention relates to a device for detecting deposits in an exhaust tract of an internal combustion engine, a test stand with a device for detecting deposits, a motor vehicle with a device for detecting deposits and a method for detecting deposits.

Diesel engines may have a selective catalytic reduction (SCR) system installed in the exhaust tract to reduce expelled nitrogen oxides. An SCR system includes a reductant injector that injects a reductant, such as an aqueous urea solution, into an exhaust conduit. The reducing agent evaporates in the hot exhaust gas and can reduce the nitrogen oxides with the aid of a catalyst.

Under certain conditions, for example low exhaust gas temperatures, the reductant may not completely evaporate. As a result, reductant deposits may form in the exhaust conduit. Such reductant deposits may, for example, adhere to the walls in the exhaust pipe or to components installed in the exhaust pipe. This can affect the respective function of the component. In addition, unevaporated reducing agent is not used for nitrogen oxide conversion and thus reduces the efficiency of the system. In addition, the deposits can take on large dimensions, up to the clogging of the exhaust pipe

The DE 10 2008 018 063 A1 discloses a method for improving the performance of an exhaust aftertreatment system of a vehicle. The method includes estimating a urea deposit accumulation in the SCR catalyst to determine timing for regenerating the SCR catalyst to remove the urea deposit accumulation.

The WO 2015/150498 A1 discloses an apparatus for detecting urea deposits in an exhaust pipe of an internal combustion engine. The apparatus includes at least one radiation receiver, which in use is disposed within the exhaust conduit downstream of the reductant agent nozzle. The device further comprises an electronic control unit in communication with the radiation receiver. The radiation receiver communicates radiation data to the control unit, which allows the control unit to determine if deposits have formed within the exhaust pipe.

Other emissions, such as unburned hydrocarbons and particulates, such as soot and ash, can lead to clogging of components such as a diesel oxidation catalyst and a diesel particulate filter.

The invention is based on the object to provide a device and a method that allows an alternative and possibly improved detection of deposits. The invention is based in particular on the object of enabling automated and rapid detection of deposits, preferably of reducing agent deposits and combustion product deposits, during operation of the internal combustion engine.

The object is achieved by an apparatus and a method for detecting deposits in an exhaust gas tract of an internal combustion engine according to the independent claims. Advantageous developments are specified in the dependent claims.

The device has an exhaust pipe and an image pickup unit. The image pickup unit is arranged to receive a surface provided in the exhaust pipe. The image acquisition unit is designed to capture and output a recording of the surface. The device has an image processing unit. The image processing unit is designed to receive a recording output by the image recording unit and process it for checking for a deposit located on the surface.

By using an automated evaluation by the image processing unit, a check for deposits, in particular equipment deposits, reducing agent deposits and / or combustion product deposits, can be carried out in real time. This also allows detection of deposits at an early stage, so that larger accumulations can be prevented. If deposits are detected, appropriate countermeasures can be initiated, for example.

The image acquisition unit may in particular comprise one or more photosensitive electronic components, e.g. CCD or CMOS sensors.

The picture can consist of a plurality of pixels.

The device can be used to check for any kind of deposit in the exhaust pipe.

Preferably, the receptacle has one or a plurality of optical images. In a plurality of optical images, the optical images may show different portions or areas of a surface or different surfaces. Alternatively or additionally, the optical images can be recorded offset in time. Thus, temporal changes of the surfaces can be analyzed as well as several areas in the exhaust pipe can be investigated.

In one exemplary embodiment, the image processing unit is configured to process the image output by the image acquisition unit for checking for resource deposition, in particular reductant deposition, deposition of a combustion product, especially soot or ash, and / or a deposition precursor (eg, resource deposition precursor, reductant deposition precursor, combustion product deposition precursor) , The deposits can be detected, for example, as a wall film in a liquid or solid state.

In one embodiment variant, the image processing unit is designed to carry out an image evaluation of the image information of the image. In particular, an image processing algorithm may be applied to the image captured by the image capture unit to check for deposition. The use of a specially adapted image processing algorithm increases the recognition accuracy and also enables the automation of the evaluation.

The image processing algorithm may compare the image with, for example, an earlier image or a comparison image that has no reduction deposits.

Image analysis can compare two or more images. The image analysis can detect temporal changes of the information in the recordings.

Additionally or alternatively, the image processing algorithm may apply a filter to the image. For example, several pixels can be combined into one pixel. The color or gray value of the combined pixel may be an average of the aggregated pixels.

Additionally or alternatively, the image processing algorithm may count the number of pixels with a gray value above a threshold.

Additionally or alternatively, the image processing algorithm may additionally classify a range of gray value above the threshold, count the number of pixels within each of these classes, and generate a corresponding histogram.

Additionally or alternatively, the image processing algorithm can directly compare the individual pixels between two images and / or use hash functions for evaluation.

In one embodiment, the image processing unit is configured to determine a size of the deposit. Alternatively or additionally, the image processing unit is designed to determine the presence of the deposit. Alternatively or additionally, the image processing unit is designed to determine a temporal change of the deposit. The determination of a size of the reductant deposit and / or the time variation of the deposit may be used to decide if a tolerance threshold is exceeded. When the tolerance threshold is exceeded, appropriate measures for reducing the reducing agent deposits and / or for preventing further reducing agent deposits can be initiated. The tolerance threshold may be provided to compensate for registration inaccuracies by the image acquisition unit.

In one embodiment, the image acquisition unit is designed as a camera, in particular an endoscope camera. The camera can be designed in particular as a 2D camera, 3D camera, camera and / or video camera.

The image recording unit is preferably designed to record a photograph in the ultraviolet range, in the visible light range and / or in the infrared range.

Advantageously, when at least partially disposed in the exhaust conduit, the imaging unit is disposed in an environmentally resistant (e.g., acid-resistant, temperature-resistant, and / or dust-proof) housing.

In a further embodiment, the device is designed to introduce a fluorescent excipient in the exhaust pipe. For example, a separate injector may be provided to introduce the fluorescent excipient. The fluorescent adjuvant may also be introduced together with or separately from a resource, such as a reductant, from a resource injector. The device may have a separate tank for the fluorescent adjuvant. The fluorescent adjuvant may also be added to or supplied to the resource in the resource tank. The fluorescent excipient may also be dissolved in the resource.

In a further embodiment variant, the image recording unit is arranged to receive an inner wall surface of the exhaust gas line. This makes it possible to check for deposits (solid or as a liquid film) on the inner wall surface of the exhaust pipe.

Alternatively or additionally, the device further comprises a component, in particular a metal sheet, a catalyst, a mixer or a particle filter. The component is arranged in the exhaust pipe. The image pickup unit is arranged to receive a surface of the component. Thus, internals in the exhaust pipe can be examined for deposits.

The component may also be provided specifically as a test body, which is arranged at critical points in the exhaust pipe for checking deposits. The test specimen can be provided for example in the form of a sheet. The test specimen can form a disturbance element for the exhaust gas flow in the exhaust gas line. For this purpose, the sheet can be arranged inclined, for example, with respect to a flow direction in the exhaust pipe, for example at an angle of 90 ° to the flow direction.

In another embodiment, the apparatus further comprises a resource injector configured and arranged to introduce a resource (e.g., a reductant or a fuel) into the exhaust conduit. The image acquisition unit may in particular be arranged downstream or upstream of the equipment injector. The image acquisition unit can thus be flexibly arranged according to the requirement and possibility. An arrangement upstream of the resource injector may prevent contamination of the image capture unit by the resource.

The reducing agent injector and / or the exhaust pipe may in particular be part of an SCR system.

The image pickup unit is preferably arranged such that an area downstream of the resource injector is within the field of view of the image pickup unit. In other words, the surface detected by the image pickup unit is located downstream of the resource injector. Thus, in particular, the areas susceptible to resource deposits can be detected by the image acquisition unit.

In a further embodiment, the device has a control unit. The control unit communicates with the resource injector in communication. The control unit is configured to control the resource injector based on the check for a deposit. For example, a reductant dosing rate for improving nitrogen oxide conversion efficiency may be increased if reductant deposits are not detected. On the other hand, a reductant dosing rate to prevent deposits can be reduced as reductant deposits are detected.

The term "control unit" refers to a control electronics, which can take over control tasks and / or regulatory tasks depending on the training.

The control unit may be in communication with the image acquisition unit in addition to driving the Betriebsmitteljektjektors. Additionally or alternatively, the control unit may be in communication with a lighting device for driving the lighting device.

Advantageously, the control unit is designed to control a metering rate by the equipment injector, in particular an opening duration, an opening frequency and / or an opening degree of the equipment injector, based on the check for deposition of the image processing unit.

In particular, the control unit is configured to reduce a metering rate of the resource injector when the image processing unit determines a presence of a deposit on the surface, a certain amount of deposit exceeds a predetermined threshold, determines a temporal change of a deposit and / or a temporal change of the deposit exceeds a limit. A reduction in dosage may prevent the formation of further deposits.

Alternatively or additionally, the control unit may initiate a measure to reduce the deposit. For example, the engine may be controlled to reduce deposition when the image processing unit determines presence of a deposit on the surface, the particular size of the reductant deposit exceeds a predetermined threshold, determines a change over time of a deposit, and / or a temporal change of the deposit determines a threshold exceeds. For this purpose, for example, an exhaust gas temperature and / or an exhaust gas mass flow can preferably be increased.

In a further embodiment, the control unit is designed for one or a plurality of engine operating points of Combustion engine to determine and / or update a maximum Betriebsmitteldosierrate in which no deposition is determined by the image processing unit, a certain size of the deposit does not exceed a predetermined limit, in which no temporal change of a deposit is determined, and / or a temporal change of the Deposit does not exceed a limit. For this purpose, the control unit, for example, gradually increase the metering dosing until a deposit is detected. This allows the automatic generation of characteristics in a test bench for later use in practice. An update may, for example, be carried out in an application in the vehicle if a maximum dosage rate determined in the vehicle deviates from that in the laboratory, in field tests or a previously determined maximum dosing rate.

The control unit may automatically sequentially control different engine operating points and determine a maximum metering rate for each engine operating point.

The maximum dosing rate can be stored in a memory of the control unit, so that it can be prevented in the future that too much operating fluid is injected.

In a further embodiment, the device further comprises a lighting device. The illumination device is arranged to illuminate the surface received by the image acquisition unit. Such a configuration has the advantage that the recording quality can be improved.

The illumination device can be used separately from the image acquisition unit as an additional unit and / or integrated into the image acquisition unit.

In particular, the illumination device can be designed to emit light with different wavelengths, in particular light in an ultraviolet range, a visible range and / or an infrared range.

It will be understood that the term "visible region of light" refers to a region of light visible to the human eye (wavelength between 380 nm and 780 nm).

The lighting device may be formed as a continuous lighting device or a flash device.

In a further embodiment, the illumination device can emit light in the ultraviolet range. This allows, for example, fluorescent excipients to be visualized in the deposits. The illumination can take place before or during the recording by the image recording unit.

The invention further relates to a test stand, in particular an engine test bench, or a motor vehicle, in particular a utility vehicle, with the device for detecting reductant deposits as disclosed herein.

In addition, the invention relates to a method for detecting deposits in an exhaust tract of an internal combustion engine. The deposits are in particular resource deposits, preferably reductant deposits, and / or combustion product deposits, preferably soot or ash. The method includes receiving a surface in an exhaust conduit. In addition, the method includes applying image processing to the recording for surface deposition verification.

As with the previously described device, the use of automated capture and evaluation allows for real-time deposition inspection. The deposits can be detected at an early stage. Possibly. appropriate countermeasures to prevent further deposits and / or to reduce or dissolve the existing deposits may be initiated.

The method may use the device as disclosed herein.

In a preferred embodiment, the method further comprises introducing a resource, in particular a reducing agent, for example an aqueous urea solution, into the exhaust gas line. The image processing is applied to the image for inspection for a deposit of the surface-active agent.

The resource may be introduced together with a fluorescent excipient. The method may further comprise, in particular, irradiating the surface with light having an excitation wavelength of the fluorescent excipient. In particular, the light may have a proportion in the ultraviolet range. This has the advantage that fluorescent reducing agent deposits can increase the recognition accuracy.

The irradiation of the surface with light may take place prior to picking up the surface or while picking up the surface.

• 1 eine schematische Ansicht einer beispielhaften Vorrichtung zur Erfassung von Reduktionsmittelablagerungen;
• 2 eine schematische Ansicht einer weiteren beispielhaften Vorrichtung zur Erfassung von Reduktionsmittelablagerungen;
• 3 ein Flussdiagramm zum Darstellen eines Verfahrens zur Kennfeldermittlung unter Verwendung der Vorrichtung zur Erfassung von Reduktionsmittelablagerungen; und
• 4 ein Flussdiagramm zum Darstellen eines Verfahrens für eine Fahrzeuganwendung unter Verwendung der Vorrichtung zur Erfassung von Reduktionsmittelablagerungen.

The preferred embodiments and features of the invention described above can be combined with one another as desired. Further details and advantages of the invention will be described below with reference to the accompanying drawings. Show it:

• 1 a schematic view of an exemplary apparatus for detecting Reduktionsmittelablagerungen;
• 2 a schematic view of another exemplary device for detecting Reduktionsmittelablagerungen;
• 3 a flowchart for illustrating a method for Kennfeldermittlung using the device for detecting Reduktionsmittelablagerungen; and
• 4 a flowchart for illustrating a method for a vehicle application using the device for detecting Reduktionsmittelablagerungen.

The embodiments shown in the figures are at least partially identical, so that similar or identical parts are provided with the same reference numerals and to the explanation of which reference is also made to the description of the other embodiments or figures in order to avoid repetition.

In the following, reference will be made in particular to a particularly preferred apparatus and a particularly preferred method for detecting reductant deposits. However, those skilled in the art will readily understand that the apparatus and method are equally useful for detecting other deposits, e.g. Deposition of other resources (e.g., diesel) or combustion products (e.g., soot or ash) are applicable.

The 1 shows a device 10 for detecting reductant deposits. The device 10 has an exhaust pipe 12 , an image capture unit 16 and an image processing unit 18 on.

The exhaust pipe 12 forms a portion of an exhaust tract of an internal combustion engine, not shown. The exhaust pipe 12 For example, it may be located downstream of an exhaust manifold of the internal combustion engine for carrying exhaust gas. The arrows A and B show a flow direction through the exhaust pipe 12 ,

A reducing agent injector 14 protrudes into the exhaust pipe 12 , The reducing agent injector 14 is adapted to a reducing agent, for example, an aqueous urea solution in the exhaust pipe 12 inject. In a known manner, the reducing agent can evaporate in the hot exhaust gas and reduce nitrogen oxide (NO _x ) in the exhaust gas by means of a catalyst.

In other embodiments, instead of the reducing agent injector 14 another equipment injector or no injector be provided. It goes without saying that the device can be provided, in particular, without a resource injector (reducing agent injector) if, for example, no SCR system is present and / or (only) combustion product deposits are to be detected.

The reducing agent injector 14 is connected via a reducing agent pump (not shown) with a reducing agent tank (not shown). A control unit 20 can the reducing agent injector 14 for injecting reducing agent.

The image capture unit 16 is arranged so that a surface in the exhaust pipe 12 in the field of view of the image acquisition unit 16 is. In the present embodiment, a portion of an inner wall surface 12A the exhaust pipe 12 in the field of view of the image acquisition unit 16 , The image capture unit 16 is designed to be the surface 12A record and output the recording, for example in the form of data signals. The image capture unit 16 For example, it can be configured as a 2D or 3D, video or photo camera. The camera may include photosensitive sensors, for example CMOS or CCD sensors.

The image capture unit 16 is designed to withstand the high temperatures and corrosive conditions in the exhaust tract of the internal combustion engine. For example, the image pickup unit may be provided in a temperature and acid resistant and dustproof housing. Alternatively or additionally, the image acquisition unit 16 be designed as an endoscope camera, for example, in the exhaust pipe 12 protruding optical fiber cable is connected to one or more photosensitive components.

In the illustrated embodiment, the image pickup unit is 16 upstream of the reducing agent injector 14 arranged. Additionally or alternatively, an image pickup unit may also be located at another position in or on the exhaust pipe 12 be arranged. The image recording unit can in particular be arranged so that surface susceptible to reducing agent deposits are located in a field of view of the image recording unit. This can be, for example, in the area of flow resistances, such as arc segments or internals in the exhaust pipe 12 , be the case. In the 1 are two more examples conceivable arrangements for the image pickup unit with the reference numerals "X" and "Y" indicated.

The image capture unit 16 is in communication with the image processing unit 18 , The image processing unit 18 can take one or more shots from the image capture unit 16 receive. The image processing unit 18 Processes the received image to detect any reductant deposits on the surface 12A capture. This can be done by the image processing unit 18 use one or a plurality of predetermined image processing algorithms.

For example, an image processing algorithm may record the surface 12A with a predefined recording of the surface 12A compare on which there are no Reduktionsmittelablagerungen. Such a comparison can also be made indirectly, for example by depositing a data record. The dataset has comparative characteristics for a situation without reductant deposits.

The comparison of two images with each other can be done by different methods. Some of which are exemplified below.

Fundamental to most methods is the consideration of the gray and color values of the individual pixels of the image. Before the actual comparison takes place, a picture can be prefiltered. One way of filtering is to merge multiple pixels into one large pixel, which has the averages of the gray levels and color values of the merged pixels as a property. Hereinafter, by pixel is meant both the pixel and the average of a plurality of pixels. During the comparison, consecutive images can be used both directly in time as well as indirectly in time (there are several images between the images to be compared). Hereinafter, some methods for image comparison will be described by way of example.

A threshold value for the gray value is defined. For each image, count the number of pixels where the gray value is above the threshold. If this number changes between two images, this is proportional to the amount of reducing agent deposits present.

Instead of counting only the number of pixels above the limit value, the range of the gray value above the limit value can additionally be divided into classes. Now count the number of pixels within each of these classes and contain a histogram based on it. Here, changing the histogram when comparing two images is proportional to the amount of reductant deposits.

The above method using a histogram can also be applied without setting a threshold. For this, the complete value range of the gray value (0: 255) is divided into classes and in turn the number of pixels of an image per class is counted. Based on this, a histogram is created. In addition to the gray value, an examination of the color values (RPG) can also be performed with this method. That is, classes are introduced for each color value and the number of pixels in each class is determined for each color value. This results in a histogram for each color value. These histograms are used to compare two or more images, and a change in the histograms indicates a change in reductant deposits.

In another method, the individual pixels between two images are directly compared. Since each image has the same total number of pixels, the individual respective pixels of two or more images can be compared directly with each other. For comparison, both gray and color values can be used. If pixels differ between images, this is a measure of reducing agent deposits.

For example, hash functions can be used as a further comparison method. Such a hash function is, for example, a cryptological hash function. In this, all color or gray values of an image are optionally noted in a unique number that is unique to these entire values (for example, MD5 hash, 32-digit hexadecimal number). This number is created for each image and can then be compared with each other. As far as pictures differ, this number is different.

It is understood that the mentioned possibilities can be combined with one another and / or other methods of image processing and / or object recognition can be used.

Is from the image processing unit 18 a reductant deposit on the surface 12A detected, so the image processing unit 18 in some embodiments, determine the size of the reductant deposits. The particular size can be compared to a threshold.

If the presence of a reductant deposit from the image processing unit 18 is detected, a size of the reducing agent deposit exceeds a threshold, a temporal change of a magnitude of Reducing agent deposition is detected or a time change of a size of the reducing agent deposit exceeds a limit, so various measures can be taken depending on the requirements and application environment. Hereinafter are with reference to 3 and 4 various methods for use on an engine test bench ( 3 ) and in a vehicle ( 4 ).

In particular, the control unit 20 that with the image processing unit 18 is in communication communication, a Reduktionsmitteldosierrate by the reducing agent injector 14 adjust to a reductant deposit based on the review.

Preferably, the control unit 20 a reducing agent metering rate by the reducing agent injector 14 reduce if a reductant deposit has been detected. For this purpose, for example, an opening frequency, an opening degree and / or an opening duration of the reducing agent injector 14 be reduced.

On the other hand, it is also possible that the control unit 20 a reducing agent metering rate by the reducing agent injector 14 increased if no reductant deposition was detected. An increase of the reducing agent metering can be particularly useful if a nitrogen oxide sensor (not shown) detects an excessively high nitrogen oxide concentration downstream of the catalyst for selective catalytic reduction. To increase the reducing agent metering, for example, an opening frequency, an opening degree and / or an opening duration of the reducing agent injector 14 increase.

The control unit 20 can also be used with the image acquisition unit 16 in communication. The control unit 20 can the image capture unit 16 to take a picture of the surface 12A drive.

The control unit 20 can be designed as an electronic control unit in a motor vehicle. Alternatively, the control unit 20 For example, be designed as a computer system of a test bench, for example, an engine dynamometer.

To illuminate the interior of the exhaust pipe 12 and in particular the surface 12A can be a lighting device 22 be provided. The lighting device 22 may be configured as a continuous lighting device or a flash device. The lighting device 22 can with the control unit 20 be connected to turn on and off or trip.

In some embodiments, the lighting device 22 in the image acquisition unit 16 , for example, as a light source of an endoscope camera, be integrated.

In some embodiments, the reducing agent may be admixed with a fluorescent adjuvant. The fluorescent adjuvant may be introduced through the reductant injector 14 or before that, for example, by adding it to the reducing agent tank. The fluorescent adjuvant can facilitate image processing by reducing agent deposits becoming more contrastive of the surface 12A drop. For further improvement, the lighting device 22 the surface 12A irradiate with light having an excitation wavelength of the fluorescent auxiliary. For example, the lighting device 22 be formed as a UV (ultraviolet light) lighting device.

The 2 shows a further embodiment of the device for detecting Reduktionsmittelablagerungen, which is provided with the reference numeral 10 '. In comparison with the embodiment of 1 the same components are provided with the same reference numerals. To avoid repetition, a description of identical components is omitted.

The device 10 'additionally has a component 24 on. The component 24 is in the exhaust pipe 12 arranged. The component 24 For example, it may be a plate, a catalyst, a mixer, or a particulate filter. The sheet may be provided, for example, for flow guidance or specifically as a test body for detecting reductant deposits.

Additionally or alternatively for receiving a portion of the inner wall surface 12A , is the image capture unit 16 adapted and arranged to receive a surface 24A of the component 24 close. Consequently, the surface can also be 24A of the component 24 be examined for reducing agent deposits. For better illumination of the surface 24A of the component 24 can the lighting unit 22 the surface 24A illuminate.

Also in the embodiment according to 2 it is possible that instead of the reducing agent injector 14 another equipment injector or no injector is provided.

The apparatus for detecting reductant deposits disclosed herein can be used in a variety of ways. The following is with reference to 3 an application example in an engine test bench and with reference to 4 an application example described in a motor vehicle. The processes can be carried out fully automatically or semi-automatically.

The 3 FIG. 10 shows an exemplary method for determining a map that sets a maximum reductant dosing rate in relation to an engine operating point. The engine operating point may be characterized, for example, by a load on the engine, cylinder pressure, cylinder temperature, accelerator pedal position, engine speed, engine torque, engine output, fuel consumption of the engine, exhaust gas temperature, and / or exhaust gas flow rate of the internal combustion engine be.

The following is the exemplary method of 3 with reference to the device of 1 described.

In a first step S100 a new engine operating point for the internal combustion engine is set. The internal combustion engine is operated at this new engine operating point. For this engine operating point, the maximum possible Reduktionsmitteldosierrate to be determined below.

In step S102 a minimum dosage of the reducing agent is set. The minimal dosage of the reducing agent can be achieved, for example, by the construction and / or controllability of the reducing agent injector 14 be predetermined. The minimum dosage is set in the form of a control command with which the reducing agent injector 14 is controlled.

The control command for driving the reducing agent injector 14 may be an opening duration, an opening frequency and / or an opening degree of the reducing agent injector 14 Respectively.

In step S104 is a reducing agent in the exhaust pipe 12 through the reducing agent injector 14 initiated. The reducing agent is introduced according to the previously set dosage.

In step S106 is from the image acquisition unit 16 a picture of the surface 12A made. To improve the recording quality is the surface 12A from the lighting device 22 illuminated during the recording. The picture, which may consist of one or more pictures, is taken by the picture-taking unit 16 to the image processing unit 18 output.

In step S108 will capture the image capture unit 16 from the image processing unit 18 processed. The image processing unit 18 Check the recording for the presence of reductant deposits on the surface 12A ,

In step S110 is checked if the image processing in step S118 has detected a reducing agent deposit. If a reductant deposition has been detected, then step S112 continued. If no reduction deposit has been detected, then step S116 continued.

In step S112 it is checked whether a detected Reduktionsmittelablagerung exceeds a limit. The limit may be defined so that only small detected reductant deposits remain insignificant, as these may for example result from inaccuracies, blurring, changing lighting conditions, and so on. The limit value can be defined, for example, as the area size of a reducing agent deposit or indirectly as a comparative characteristic value.

If the limit has been exceeded, then the map to be created in step S114 updated. In particular, the current reductant dosing rate or pre-set reductant dosing rate, at which the reductant deposits have not yet exceeded a threshold, is updated as the maximum possible reductant dosing rate for the set engine operating point. The procedure starts again at step S100 with the setting of a new engine operating point for which a maximum metering rate is to be determined.

If no limit has been exceeded (step S112 ) or no deposit has been detected (step S110 ), the reducing agent metering rate in step S116 elevated. The procedure starts again at step S104 with the introduction of the reducing agent.

The 4 shows a method that can be used during operation of a motor vehicle.

The steps S200 to S208 essentially like the steps S104 to S112 be performed so that a detailed description is omitted to avoid repetition.

Will in step S206 no deposit recorded or in step S208 If no limit value is exceeded, the method will be in another loop with a restart at step S200 carried out.

Will in step S208 exceeded a limit, so in step S210 appropriate countermeasures are taken. To detach The reducing agent deposits can be increased, for example, an exhaust gas temperature and / or an exhaust gas flow amount.

Additionally, in step S210 an example stored in the control unit map with respect to the maximum Reduktionsmitteldosierrate be updated.

In step S212 If desired, a dosing rate can be adjusted. For example, a dosing rate may be increased if no deposits are detected or no limit is exceeded. For example, a dosing rate may be reduced if a threshold for the deposit is exceeded.

The invention is not limited to the preferred embodiments described above. Rather, a variety of variants and modifications is possible, which also make use of the inventive idea and therefore fall within the scope. In particular, the invention also claims protection of the subject matter and the features of the subclaims independently of the claims referred to.

LIST OF REFERENCE NUMBERS

10

Device for detecting reductant deposits (deposits)

12

exhaust pipe

12A

Inner surface of the exhaust pipe

14

Reductant injector (resource injector)

16

Imaging unit

18

Image processing unit

20

control unit

22

lighting device

24

Component in exhaust pipe

24A

Surface of the component

A, B

flow direction

X, Y

Possible positions for image acquisition unit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008018063 A1 [0004]
• WO 2015/150498 A1 [0005]

Claims (15)

Device (10) for detecting deposits in an exhaust tract of an internal combustion engine, comprising: an exhaust pipe (12); an image pickup unit (16) arranged to receive a surface (12A, 24A) provided in the exhaust pipe (12), the image pickup unit (16) adapted to detect and output a photograph of the surface (12A, 24A); and an image processing unit (18) adapted to receive the image output from the image pickup unit (16) and to process it for inspection on a deposit located on the surface (12A; 24A). Device (10) according to Claim 1 wherein the receptacle has one or a plurality of optical images, which are recorded in particular offset in time and / or show different areas of the surface (12A, 24A). Device after Claim 1 or Claim 2 wherein: the image processing unit (18) is adapted to process the image output by the image acquisition unit (16) for inspection for resource deposit, in particular reductant deposition, deposition of a combustion product, in particular soot or ash, and / or a deposition precursor; and / or the image processing unit (18) is designed to carry out an image evaluation of the image information of the image, the image processing unit (18) in particular applying an image processing algorithm to the image acquired by the image recording unit (16) for checking for deposition. Device (10) according to one of the preceding claims, wherein the image processing unit (18) is designed to: to determine a size of the deposit; and or to determine a presence of the deposit; and or to determine a temporal change of the deposit. Device (10) according to one of the preceding claims, wherein: the image acquisition unit (16) is designed as a camera, in particular an endoscope camera; and or the image acquisition unit (16) is designed to record a photograph in the ultraviolet range, in the visible light range and / or in the infrared range; and or the device (10) is adapted to introduce a fluorescent excipient into the exhaust pipe (12). Device (10) according to one of the preceding claims, wherein: the image pickup unit (16) is arranged to receive an inner wall surface (12A) of the exhaust pipe (12); and or the apparatus (10) further comprises a component (24), in particular a sheet metal, a catalyst, a mixer or a particle filter, which is arranged in the exhaust pipe (12), wherein the image recording unit (16) for receiving a surface (24A) of the component (24) is arranged. Device (10) according to Claim 6 wherein the component (24) as a test specimen, in particular in the form of a sheet is formed, wherein the test body forms a disturbance element for an exhaust gas flow in the exhaust pipe (12) and is preferably arranged inclined with respect to a flow direction in the exhaust pipe (12) , in particular at an angle of 90 ° to the flow direction. Device (10) according to one of the preceding claims, further comprising a Betriebsmittelinjektor (14) which is designed and arranged for introducing a resource, in particular diesel or a reducing agent in the exhaust pipe (12), wherein the image pickup unit (16) preferably downstream or is disposed upstream of the fuel injector (14). Device (10) according to Claim 8 , further comprising a control unit (20) in communication with the resource injector (14) and configured to control the resource injector (14) based on the review of a deposit of the image processing unit (18). Device (10) according to Claim 9 wherein the control unit (20) is adapted to: reduce a dosing rate of the resource injector (14) when the image processing unit (18) determines presence of a deposit on the surface (12A; 24A), a certain amount of deposit exceeds a predetermined threshold , a temporal Change of a deposit determined and / or a temporal change of the deposit exceeds a threshold; and / or initiates a deposit reducing operation, in particular controlling the internal combustion engine for increasing exhaust gas temperature and / or exhaust gas flow rate, when the image processing unit (18) determines presence of deposit on the surface (12A; Deposit exceeds a predetermined limit, determines a temporal change of a deposit and / or a temporal change of the deposit exceeds a threshold. Device (10) according to Claim 9 or Claim 10 wherein the control unit (20) is adapted to determine and / or update, for one or a plurality of engine operating points of the internal combustion engine, a maximum resource metering rate at which no deposit is determined by the image processing unit (18) having a particular size Deposition does not exceed a predetermined limit at which no change over time of a deposit is determined and / or a temporal change of the deposit does not exceed a limit value. Apparatus (10) according to any one of the preceding claims, further comprising a lighting device (22) arranged to illuminate the surface (12A, 24A) received by the image pickup unit (16) and integrated in particular in the image pickup unit (16), the lighting device (22) is preferably adapted to emit light in an ultraviolet region, a visible region and / or an infrared region. Test bench, in particular engine test bench, or motor vehicle, in particular commercial vehicle, with the device (10) according to one of the preceding claims. Method for detecting deposits in an exhaust gas tract of an internal combustion engine, in particular operating medium deposits, preferably reducing agent deposits, and / or combustion product deposits, comprising: Receiving a surface (12A, 24A) in an exhaust conduit (12); and Applying image processing to the image to check for deposition on the surface (12A, 24A). Method according to Claim 14 , further comprising: introducing a resource, in particular a reducing agent, for example a urea aqueous solution, into the exhaust conduit, wherein the image processing is applied to the receptacle for checking for deposition of the agent on the surface (12A, 24A) and the reducing agent in particular with a fluorescent excipient, and the method further preferably comprises irradiating the surface (12A, 24A) with light having an excitation wavelength of the fluorescent excipient.

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