Coating device for a substrate body

Abstract

The present invention relates to a coating device for coating through-channels of a substrate body with a catalytically active coating suspension, which comprises a holder for receiving the substrate body, a supply for the coating suspension, and a suction system for providing a vacuum in the region of the lower end face of the substrate body, wherein the suction system is designed to infiltrate the supplied coating suspension into the through-channels and / or to remove coating suspension located in the through-channels, and at least one pressure sensor is arranged to measure a pressure directly in the region of the lower end face of the substrate body.

Description

[0001] Coating device for a substrate body

[0002] Description

[0003] Technical area

[0004] The invention relates to coating devices for substrate bodies having a plurality of through-channels, in particular for coating ceramic substrate bodies with a particularly catalytically active coating suspension.

[0005] Technical background

[0006] Catalytic converters for exhaust gas aftertreatment are essentially formed from a cylindrical ceramic or metallic substrate body provided with a multitude of through-flow channels running parallel to the axial direction. The inner surfaces of the flow channels are coated with a catalytically active coating material and, during operation, are subjected to combustion exhaust gases from internal combustion engines. This initiates a catalytic reaction in which pollutants such as carbon monoxide, hydrocarbons, and nitrogen oxides are converted into less harmful compounds.

[0007] When coating the substrate body, it is necessary that a catalytically active coating suspension is deposited over the entire axial length or part thereof on the inner surfaces of the through-channels in the substrate body so that a homogeneous coating is achieved without the coating material clogging individual through-channels.

[0008] For coating such a substrate body, coating devices are known in which coating material is infiltrated into the through-channels and then, if necessary, the coating material is sucked out of the through-channels by applying a pressure difference across the substrate body, e.g., by applying a negative pressure. The suction creates a pressure drop in the through-channels, through which excess coating material is sucked out or removed, thereby achieving a layer thickness that is as uniform or homogeneous as possible. For example, EP 1 273 344 A1 discloses a method for coating a cylindrical support body with a predetermined amount of a coating suspension, wherein the empty volume of the support body is filled to a predetermined fill level, and excess coating suspension is removed through the lower end face of the support body.

[0009] One difficulty during the coating process is determining when, after infiltration or suction of the coating material, the through-channels are free or permeable again, allowing the coated substrate to be removed and the next substrate to be coated. To date, the cycle time of such a coating process has been set sufficiently high to reliably achieve through-channels completely free of excess coating suspension. To reliably achieve complete permeability of the through-channels under all manufacturing conditions, the duration during which the negative pressure is applied beneath the substrate is set high, significantly extending the coating time and thus the entire manufacturing process.

[0010] Furthermore, only a small number of state variables of the coating device are available during the entire coating process, so that quality control is not possible or only possible by random sampling after the production of a batch.

[0011] It is an object of the present invention to provide a coating device with which an optimization of the coating process for substrate bodies can be achieved, in particular by reducing the cycle time, and which also enables quality control of the coating.

[0012] This object is achieved by the coating device for a substrate body with through-channels according to claim 1.

[0013] Further embodiments are specified in the dependent claims.

[0014] According to a first aspect, a coating device for coating through-channels of a substrate body with a catalytically active coating suspension comprises: a holder for receiving the substrate body, a feed configured to feed coating suspension, a suction system for providing a negative pressure in the region of a lower end face of the substrate body in a suction process, wherein the suction system is configured to infiltrate the supplied coating suspension into the through-channels and / or to remove coating suspension located in the through-channels; and at least one pressure sensor arranged on the holder to measure a pressure directly in the region of the lower end face of the substrate body.

[0015] The coating device is used to coat the substrate body with the coating suspension, which is particularly catalytically active. For this purpose, the substrate body is placed on the holder, and a coating suspension is added. If, in an apply-suction coating process, the coating suspension is added from the top of the substrate body, the suction process infiltrates the coating suspension into the through-channels, so that a layer of the coating suspension material is deposited on the inner walls of the through-channels until the entire coating suspension infiltrated into the through-channels has been applied to the inner walls and the through-channels are cleared. Ideally, the pressure difference across the substrate body decreases to a back pressure for the substrate body with fully open through-channels.

[0016] If, in a pump-suction coating process, the coating suspension is fed from the underside of the substrate body, the coating suspension is at least partially drawn into the through-channels. Subsequently, a vacuum is applied to a lower end face of the substrate body via the holder, creating a pressure gradient across the substrate body filled with coating suspension, i.e., between the end faces of the substrate body. This sucks excess coating suspension out of the through-channels, and the pressure difference across the substrate body ideally reduces to a back pressure for the substrate body with fully continuous through-channels.

[0017] The coating device can have a control unit which is designed to evaluate a pressure profile of the pressure values ​​of the at least one pressure sensor and, depending on the evaluation result, to control the coating process, to carry out a quality control and / or to signal the evaluation result.

[0018] Furthermore, the control unit can be designed to terminate the suction process depending on a pressure curve of the pressure values ​​of the measured pressure.

[0019] In particular, the control unit can be designed to operate the suction process by the suction system so that the supplied coating suspension is infiltrated into the through-channels in the apply-suction coating process or the coating suspension located in the through-channels is removed in the pump-suction coating process, and to stop the suction process at a stop time, wherein the stop time is determined after reaching a minimum of the pressure curve by detecting a plateau of the pressure curve for a predetermined period of time.

[0020] Depending on the nature of the substrate body, the applied negative pressure, and the coating suspension, the time required for the through-channels to become permeable after coating varies. Using the pressure sensor located directly on the lower end face of the substrate body, it is possible to detect the complete permeability of the through-channels and terminate the coating process accordingly if it is determined that the through-channels are permeable.

[0021] It can be provided that the control unit is designed to determine, from the pressure curve of the pressure values ​​of the measured pressure, curve features, in particular a minimum pressure and / or a pressure gradient and / or an average value of the pressure values ​​within a predetermined time window, wherein, depending on the curve features, in particular the minimum pressure and / or the pressure gradient and / or the average value, a quality of the coated substrate body is determined and signaled and / or the coated substrate body is rejected. The quality of the produced substrate body can be determined using a suitable quality model, which can be data-based, for example, and can be provided, for example, as a trained neural network for classifying the produced substrate bodies.

[0022] The control unit can also carry out quality control of the coating process depending on the pressure profile. For this purpose, a maximum pressure difference, i.e. a minimum of the pressure measured by the pressure sensor, can be recorded, which represents a measure of the process conditions of the coating process. For example, if in the pump-suction coating process the through channels are only partially filled with coating suspension, i.e. only coated over a certain zone length, and some through channels remain unfilled, a smaller pressure difference develops across the substrate body, which can be determined by the corresponding pressure minimum. Furthermore, after a pressure plateau is reached and the excess coating suspension has been sucked off, an average value can be determined over a period of time. This provides information about the back pressure of the coated substrate body. This represents a measure of product quality.

[0023] In the pump-suction coating process, the coating suspension is introduced into the through-channels via the lower end face. For this purpose, the holder can be provided with a chamber for accommodating at least the lower end face of the substrate body, wherein the feed for the coating suspension is connected to the chamber in such a way that the coating suspension is fed to the lower end face of the substrate body, thereby reaching the through-channels. The at least one pressure sensor is arranged in the chamber.

[0024] Furthermore, the chamber is filled with coating suspension during the coating process, so that the substrate body is immersed in the coating suspension. With this latter feed variant, for example, the fill level of the coating suspension can be detected using the pressure sensor. Thus, by monitoring the pressure curve during the filling process, the fill level can be adjusted during controlled operation. Furthermore, the pressure curve during filling with coating suspension can be monitored.

[0025] It has been determined that the filling pressure with the coating suspension significantly influences the quality of the coating on the substrate body. In particular, the filling pressure during filling with coating suspension should be below a predetermined threshold. By monitoring the pressure curve even during filling, a further quality control measure can be implemented.

[0026] It can be provided that the control unit is designed to control the feed so that the coating suspension is fed to the chamber at a set mass flow, to monitor the pressure profile after the start of the feed using the at least one pressure sensor and to determine a time at which the measured pressure exceeds a predefined threshold value, to determine a time period depending on a predefined zone length, which time period is determined by a predefined zone length depending on the set mass flow; and to carry out the feed for the time period after the determined time and to switch off after the time period has elapsed.

[0027] In this way, it is possible to ensure consistent quality of the coated substrate body, since after the excess coating suspension has been removed from the through-channels, the suction process is not continued for a variable period of time. Instead, the suction process ends at a time determined by a predetermined period of time after the through-channels have become clear.

[0028] Alternatively, in an apply-suction coating process, the holder can have a chamber for accommodating at least the lower end face of the substrate body, wherein the feed for the coating suspension is arranged such that the coating suspension is fed to the upper end face of the substrate body, so that when the negative pressure is applied, it infiltrates the through-channels in a suction process. The coating suspension can thus be fed by applying the coating suspension to an upper end face of the substrate body. The application of the negative pressure then causes the coating suspension to be sucked into the through-channels of the substrate body, so that the material of the coating suspension is deposited on the inner walls of the through-channels.

[0029] In this regard, the control unit can be designed to determine a zone length of coating suspension introduced into the through-openings depending on a minimum of the pressure curve and the time period between a start of the feed and the time at which the minimum is reached and / or to determine a pressure value of a plateau of the pressure curve after the minimum of the pressure curve has been reached, and to determine and signal a quality of the coating of the through-channels of the substrate body with the coating suspension depending on the zone length or the pressure value of the plateau of the pressure curve and / or to discard the coated substrate body.For both of the above variants of supplying the coating suspension, the control unit can be designed to operate the suction process by the suction system so that the permeability of the through-channels is restored after / during the coating, and to stop the suction process at a stop time, wherein the stop time is determined after reaching a minimum of the pressure curve by detecting a then developing plateau of the pressure curve for a predetermined period of time.

[0030] A plurality of pressure sensors can be arranged distributed along a floor and / or circumferentially distributed along the inner wall of the chamber, wherein the control unit is configured to evaluate a pressure profile of the pressure values ​​of the plurality of pressure sensors. Furthermore, the control unit can be configured to variably control the feed in order to deliver a variable, adjustable suspension mass flow into the chamber depending on the pressure profiles measured by the pressure sensors.

[0031] The coating device preferably comprises a plurality of pressure sensors distributed across the holder so that pressures from different areas of the lower end face of the substrate body can be detected. In this way, pressure variations during the filling process that occur due to turbulence can be detected. If one of the measured pressure values ​​exceeds a predefined threshold value or if the pressure variations exceed a predefined threshold value, this can be signaled accordingly. Alternatively or additionally, a suspension mass flow for supplying the coating suspension can be adjusted accordingly depending on the magnitude of the pressure variations and the pressure levels.

[0032] Furthermore, the control unit can be designed to reduce the suspension mass flow if excessive pressure differences occur between the pressure sensors arranged on the same horizontal plane.

[0033] The control unit can further be configured to signal an error or to reject the substrate body if excessive pressure differences arise between the pressure sensors arranged on the same horizontal plane. It can be provided that several pressure sensors are arranged at different horizontal planes on an inner wall of the chamber, wherein the control unit is configured to variably control the feed in order to convey a variable, adjustable suspension mass flow into the chamber depending on the pressure profiles measured by the pressure sensors arranged at different horizontal planes, in particular to adjust a fill level.

[0034] Furthermore, by evaluating the pressure variations of the multiple pressure values, the quality of the coating suspension filling process can be monitored, particularly to determine whether excessive turbulence is occurring or whether air bubbles are forming that could impair the quality of the coating. In particular, the control unit can reduce the suspension mass flow if excessive pressure variations are detected via the pressure values ​​of the pressure sensors.

[0035] Brief description of the drawings

[0036] Embodiments are explained in more detail below with reference to the attached drawings. They show:

[0037] Figure 1 is a schematic representation of a coating device for an apply-suction suspension coating process of a substrate body;

[0038] Figure 2 is a schematic representation of a pressure measured by a pressure sensor on the lower end face of the substrate body;

[0039] Figure 3 is a schematic representation of a coating device for a pump-suction coating process of a substrate body;

[0040] Figure 4 is a schematic representation of a holder for the coating device of Figure 3 in a plan view;

[0041] Figure 5 is a schematic sectional view of a holder for the coating device of Figure 3. Description of embodiments

[0042] Figure 1 shows a schematic representation of a coating device 1 for an apply-suction coating process for applying a coating to a substrate body 2. The substrate body 2 comprises a plurality of closely arranged through-channels 21, which run essentially parallel to one another in the axial direction and are open towards the end faces of the substrate body 2. The wall thickness between adjacent through-channels 21 can, for example, be between 0.05 and 1 mm, or the density of the through-channels can be approximately 10 cm -2 up to 250 cm -2 be.

[0043] The substrate body 2 can be made of a ceramic material. Any ceramic materials commonly used in the prior art can be used to produce a catalyst body. Porous substrate materials made of corderite, silicon carbide, or aluminum titanate are preferred.

[0044] The coating device 1 comprises a coating chamber 3 in which the substrate body 2 is held in a holder 31. When the substrate body 2 is picked up, an application stamp 34 is placed on an upper end face of the substrate body 2.

[0045] The application stamp 34 is connected to a reservoir 4 via a pump 5. The reservoir 4 contains coating suspension 41 for introduction into the through-channels 21 of the substrate body 2. The application stamp 34 has a chamber into which the coating suspension 41 is introduced prior to a coating process. The coating suspension 41 is then applied to the upper end face of the substrate body 2 via openings in a base plate of the application stamp 34. Such an arrangement is known, for example, from the document EP2415522B1.

[0046] The coating suspension 41 is liquid and can contain catalytically active components or their precursors for coating exhaust filters for motor vehicles. Oxides of vanadium, chromium, manganese, iron, cobalt, copper, zinc, nickel, or rare earth metals such as lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or combinations thereof can be used as catalytically active components. Precious metals such as platinum, palladium, gold, rhodium, indium, osmium, ruthenium, and combinations thereof can also be used as catalytically active components. These metals can also be present as alloys with one another or with other metals, or as oxides.In the liquid coating suspension 41, the metals can also be present as precursors, such as nitrates, sulfites, or organyls of the aforementioned precious metals, as well as mixtures thereof; in particular, palladium nitrate, palladium sulfite, platinum nitrate, platinum sulfite, or Pt(NH3)4(NO3)2 can be used. The catalytically active component can then be obtained from the precursor by calcination at approximately 400°C to approximately 700°C.

[0047] The holder 31 has at least one discharge channel 32, which is connected to a vacuum container 6 and a vacuum pump 7 via an extraction system 33. The holder 31 can enclose the substrate body such that the substrate body 2 is connected to the extraction system 33 in a pressure-tight manner.

[0048] By activating the vacuum pump 7, a negative pressure is generated in the extraction system 33, through which the applied coating suspension 41 is sucked from the upper end face of the substrate body 2 through the through-channels 21 due to the differential pressure between the upper end face and the lower end face, so that a layer of the coating suspension 41 is deposited on the inner surfaces of the through-channels 21 until no material of the coating suspension blocks the through-channels. If a larger amount of coating suspension is introduced, any excess coating suspension 41 can be removed via the extraction system 33 and deposited in the vacuum container 6.

[0049] A control unit 10 is provided to control the coating process. After the substrate body 2 is inserted into the holder, the pump 5 is first activated, which applies the coating suspension 41 to the substrate body 2 through the application stamp 32. The amount of coating suspension 41 is measured by controlling the pump 5 or by other means, so that a predetermined amount of coating suspension 41 is applied to the substrate body 2 through the application stamp 32.

[0050] Subsequently, the application stamp 32 is activated by a suitable device so that the coating suspension 41 is applied as evenly as possible to the upper end face of the substrate body 2. By setting a negative pressure in the vacuum container 6 by activating the vacuum pump 7 or by opening a valve (not shown) in the extraction system 33 during an extraction process, a negative pressure is created directly below the lower end face of the substrate body 2 in the region of the holder 31, which leads to a pressure difference between the upper end face of the substrate body 2 and the lower end face of the substrate body 2. This negative pressure causes the coating suspension 41 to be sucked into / infiltrated into the through-channels 21 of the substrate body 2.

[0051] To control the coating process, a pressure sensor 8 is provided in the area of ​​the holder 31 between the lower end face of the substrate body 2 and the holder 31 or at the connection of the holder 31 to the extraction system 33 to measure a profile during the coating process. The pressure sensor 8 can be provided as an absolute pressure sensor or as a differential pressure sensor for measuring a differential pressure with respect to a pressure in the area of ​​the upper end face of the substrate body 2 or with respect to an ambient pressure.

[0052] The pressure sensor 8 can be mounted at a distance of 0.1 cm to 50 cm from the underside of the inserted substrate body 2. One or more pressure sensors mounted around the circumference of the holder 31 can be used, or several pressure sensors can be mounted along the flow direction at different distances from the underside of the substrate body 2.

[0053] Figure 2 shows, by way of example, the pressure curve in the region of the lower end face of the substrate body 2. It can be seen that after the suction process is activated, the pressure initially drops (P3) until a pressure minimum M is reached, since the flow of air (or another inert gas) through the through-channels 21 is prevented by the coating suspension 41 located therein. As the through-channels 21 become increasingly free, air flows through the through-channels 21, so that the pressure in the region of the lower end face slowly increases (P1). If all through-channels 21 are free of excess coating suspension 41, no significant pressure change (P2) occurs and the suction process of removing the unnecessary coating suspension 41 is terminated.

[0054] The pressure progression phase P2 can be used to control the coating process. If it is determined that no pressure change above a specified threshold occurs within a specified time window, it can be assumed that all of the coating material has been deposited on the inner walls of the through-channels 21 or has been suctioned off via the underside, and that the through-channels 21 are completely free of coating suspension 41. The coating process can then be terminated. Upon completion of the coating process, the suction process is terminated.

[0055] Furthermore, the minimum pressure and an average value of the measured pressure can be monitored within the specified time window before the extraction process is switched off. If it is determined that the minimum pressure and the average pressure are outside predetermined limits, the coated substrate body 2 can be treated as scrap and discarded. In particular, an excessively low minimum pressure indicates passage channels 21 that are not filled with coating suspension 41, while an excessively low average value indicates passage channels 21 from which the coating suspension 41 cannot be removed and which therefore remain closed. This results in a back pressure that is too high for the intended application as an exhaust gas catalyst.

[0056] Furthermore, the control unit 10 can evaluate the pressure curve in phase P3, which corresponds to an initial pressure drop down to a pressure minimum. Here, a zone length of coating suspension 41 introduced into the through-openings can be determined based on the detection of a minimum in the pressure curve and a time period between the start of suspension infiltration and the time at which the minimum is reached.

[0057] By comparing the determined zone length with a desired zone length, the quality of the coated substrate body can be determined.

[0058] Alternatively or additionally, the control unit 10 can determine a pressure value of a plateau of the pressure curve after reaching the minimum of the pressure curve. The quality of the coating of the through-channels of the substrate body with the coating suspension can be determined depending on the pressure value of the plateau of the pressure curve. In particular, the pressure value of the plateau can be compared with a predetermined target value, whereby the result of the comparison indicates the quality of the coated substrate body. The target value can be determined from previous test measurements. Finally, the control unit can signal the quality of the substrate body and / or reject the coated substrate body if the quality requirements are not met.

[0059] Furthermore, the control unit can operate the extraction process in such a way that the coating suspension in the passageways is either deposited as a wall coating on the interior walls or removed. The extraction process can be stopped at a certain time, whereby the stop time is determined after reaching a minimum of the pressure curve by detecting a plateau in the pressure curve for a predetermined period of time. The predetermined period of time can, for example, be between 50 ms and 10 s. A plateau can be detected if the pressure value fluctuates by no more than 5% within the observed period.

[0060] Figure 3 shows a schematic representation of a further embodiment of a coating device 51 for applying a coating in the substrate body 2 using a pump-suction coating process.

[0061] The coating device 51 comprises a coating chamber 53 in which the substrate body 2 is held in a holder 531. When the substrate body 2 is received, a discharge cover 534 is placed on an upper end face of the substrate body 2 to collect escaping coating suspension 541.

[0062] The holder 531 is connected to a reservoir 54 via a pump 55. The reservoir 54 contains coating suspension 541 for introduction into the through-channels 21 of the substrate body 2. The holder 531 has a chamber 535 into which the substrate body 2 is inserted, at least with its lower end face, prior to a coating process. When the substrate body 2 is accommodated, the chamber 535 can be sealed at its upper opening to the substrate body 2, so that upon filling, the coating suspension only rises through the through-channels 21.

[0063] Subsequently, the chamber 535 is filled with coating suspension 541 by activating the pump 55. By selecting the amount of coating suspension 541 introduced into the chamber 535, the fill level can be determined and thus the height or length of the coating in the through-channels 21 can be determined. The penetration of the coating suspension 541 into the through-channels 21 can occur through a capillary effect or through the pressure of the coating suspension.

[0064] The holder 531 has one or more discharge channels 532, which are connected to a vacuum container 56 and a vacuum pump 57 via an extraction system 533. The holder 531 can enclose the substrate body 2 such that the substrate body 2 is connected to the extraction system 533 in a pressure-tight manner.

[0065] By activating the vacuum pump 57, a negative pressure is generated in the suction system 533, through which the introduced coating suspension is sucked out of the through-channels 21 of the substrate body 2 due to the differential pressure between the upper end face and the lower end face, so that a layer of the coating suspension remains on the inner surfaces of the through-channels 21. Excess coating suspension is removed via the suction system 533 and deposited in the vacuum container 56.

[0066] Since the coating suspension 54 cannot be introduced uniformly into the chamber 535, turbulence occurs when the coating suspension 541 is introduced into the chamber. These turbulences lead to pressure variations in the introduced coating suspension 541 at the lower end face of the substrate body 21, which can result in different coating qualities within the through-channels 21.

[0067] Therefore, an arrangement of several pressure sensors 58 is provided within the chamber 535 to evaluate a pressure distribution of the coating suspension 541 during the filling process of the chamber 535. The pressure sensors 58 can be provided as absolute pressure sensors or as differential pressure sensors for measuring a differential pressure with respect to a pressure in the region of the upper end face of the substrate body 2.

[0068] It can be provided that the control unit controls the feed so that the coating suspension is fed into the chamber at a set mass flow. After the feed has begun, the pressure profile is monitored using the at least one pressure sensor, and a point in time at which the measured pressure exceeds a predefined threshold is determined. Depending on a predefined zone length, a time period is determined, which is determined by a predefined zone length based on the set mass flow. The feed is carried out for the period following the determined point in time and is switched off after the time period has elapsed.

[0069] Furthermore, in the embodiment of Figure 3, the control unit can operate the suction process in such a way that the coating suspension located in the through-channels is removed. The suction process can be stopped at a stop time, whereby the stop time is determined after reaching a minimum of the pressure curve by detecting a plateau in the pressure curve for a predetermined period of time. The predetermined period of time can be, for example, between 50 ms and 150 ms. A plateau can be detected if the pressure value fluctuates by no more than 5% within the observed period.

[0070] Figure 4 shows a plan view of the holder 531 with a plurality of pressure sensors 58 arranged distributed in the circumferential direction on an inner wall of the chamber 535. Furthermore, Figure 5 shows a cross-sectional view through the holder 531 with a plurality of pressure sensors 58 arranged offset in the axial direction, ie in the height direction.

[0071] A control unit 60 is provided to control the coating process. After inserting the substrate body 2 into the holder 531, the pump 55 is first activated to introduce coating suspension into the chamber 535. The amount of coating suspension 541 is measured by controlling the pump 55 or by evaluating the pressure values ​​of the pressure sensors 58, so that a predetermined amount of coating suspension 41 is present in the chamber 535.

[0072] By setting a negative pressure in the extraction system 533 by activating the vacuum pump 57 or by opening a valve (not shown) in the extraction system 533 during an extraction process, a negative pressure is created directly below the lower end face of the substrate body 2 in the region of the holder 531, which leads to a pressure difference between the upper end face of the substrate body 2 and the lower end face of the substrate body 2. This negative pressure causes the coating suspension 41 to be extracted from the through-channels 21 of the substrate body 2.

[0073] In addition to the functions described above for controlling the coating process by regulated adjustment of the cycle time and quality control, the process of introducing the coating suspension 541 into the chamber 535 can also be monitored and, if necessary, controlled.

[0074] The control unit 60 can variably control the pump 55 to deliver a variable, adjustable suspension mass flow into the chamber 535. The suspension mass flow can be adjusted depending on the pressure profiles measured by the pressure sensors 58. In particular, the suspension mass flow can be reduced if excessive pressure differences arise between the pressure sensors 58 arranged on the same horizontal plane. This indicates strong turbulence, which can lead to varying inputs of coating suspension into the through-channels 21.

[0075] Alternatively or additionally, excessive pressure differences can also be indicated by an appropriate alarm or other signaling. Furthermore, excessive pressure differences can also lead to the termination of the coating process and the rejection of the substrate body.

[0076] Furthermore, the filling process into the chamber 535 can be controlled based on pressure sensors 58 arranged in various horizontal planes. These allow the level of the coating suspension in the chamber 535 to be detected, so that the coating length within the through-channels 21 can be adjusted and / or so that an excessive amount of coating suspension can be prevented from escaping from the upper end face of the substrate body 2.

Claims

Patent claims 1. Coating device (1; 51) for coating through-channels (21) of a substrate body (2) with a catalytically active coating suspension (41; 541), comprising: a holder (31; 531) for receiving the substrate body (2), a feed which is designed to feed the coating suspension (41; 541), a suction system (33; 533) for providing a negative pressure in the region of a lower end face of the substrate body (2) in a suction process, wherein the suction system (33; 533) is designed to infiltrate the supplied coating suspension (41) into the through-channels (21) and / or to remove coating suspension (41; 541) located in the through-channels (21); and at least one pressure sensor (8; 58) arranged on the holder (31; 531) to measure a pressure directly in the region of the lower end face of the substrate body (2).

2. Coating device (1; 51) according to claim 1 with a control unit (10; 60) which is designed to evaluate a pressure curve of the pressure values ​​of the at least one pressure sensor (8; 58) and, depending on the evaluation result, to control the coating process, to carry out a quality control and / or to signal the evaluation result.

3. Coating device (1; 51) according to claim 2, wherein the control unit (10; 60) is designed to terminate the suction process depending on a pressure curve of the pressure values ​​of the measured pressure.

4. Coating device (1; 51) according to claim 3, wherein the control unit (10; 60) is designed to operate the suction process by the suction system (33; 533) so that the supplied coating suspension (41) is drawn into the through-channels (21) is infiltrated or the coating suspension (41; 541) located in the through-channels (21) is removed, and to stop the suction process at a stop time, wherein the stop time is determined after reaching a minimum of the pressure curve by detecting a plateau of the pressure curve for a predetermined period of time.

5. Coating device (1; 51) according to one of claims 2 to 4, wherein the control unit (10; 60) is designed to determine a minimum pressure and / or a pressure gradient and / or an average value of the pressure values ​​within a predetermined time window from the pressure curve of the pressure values ​​of the measured pressure, wherein depending on the minimum pressure and / or a pressure gradient and / or the average value, a quality of the coated substrate body (2) is determined and signaled and / or the coated substrate body (2) is discarded.

6. Coating device (1; 51) according to one of claims 2 to 5, wherein the holder (31; 531) has a chamber (535) for receiving at least the lower end face of the substrate body (2), wherein the feed for the coating suspension (41; 541) is connected to the chamber (535) in such a way that the coating suspension (41; 541) is fed to the lower end face of the substrate body (2) so that it reaches the through-channels (21), wherein the at least one pressure sensor (8; 58) is arranged in the chamber.

7. Coating device (1; 51) according to claim 6, wherein the control unit (10; 60) is designed to control the feed so that the coating suspension (41; 541) is fed to the chamber at a set mass flow, to monitor the pressure curve after the start of the feed using the at least one pressure sensor (8; 58) and to determine a time at which the measured pressure exceeds a predetermined threshold value, in order to determine a time period depending on a predetermined zone length, which time period is determined depending on the set mass flow by a predetermined zone length; and to carry out the supply for the period of time after the determined time and to switch off after the period of time has elapsed.

8. Coating device (1; 51) according to one of claims 2 to 5, wherein the Holder (31; 531) has a chamber for receiving at least the lower end face of the substrate body (2), wherein the feed for the Coating suspension (41; 541) is arranged so that the Coating suspension (41; 541) is supplied to the upper end face of the substrate body (2) so that it reaches the through-channels (21) as a result of the suction process, wherein the at least one pressure sensor (8; 58) is arranged in the chamber (535).

9. Coating device (1; 51) according to claim 8, wherein the control unit (10; 60) is designed to determine a zone length of coating suspension (41; 541) introduced into the through-openings as a function of a minimum of the pressure profile and the time period between a start of the suspension infiltration and the time at which the minimum is reached and / or to determine a pressure value of a plateau of the pressure profile after the minimum of the pressure profile has been reached, and to determine and signal a quality of the coating of the through-channels (21) of the substrate body (2) with the coating suspension (41; 541) as a function of the zone length or the pressure value of the plateau of the pressure profile and / or to discard the coated substrate body (2).

10. Coating device (1; 51) according to one of claims 6 to 9, wherein the control unit (10; 60) is designed to operate the suction process by the suction system (33; 533) so that the coating suspension (41; 541) located in the through-channels (21) is removed or so that the supplied coating suspension (41) is infiltrated into the through-channels (21), and to stop the suction process at a stop time, wherein the stop time is determined after reaching a minimum of the pressure curve by detecting a plateau of the pressure curve for a predetermined period of time.

11. Coating device (1; 51) according to one of claims 6 to 10, wherein a plurality of pressure sensors (8; 58) are arranged distributed on a floor and / or distributed in the circumferential direction on the inner wall of the chamber, wherein the control unit (10; 60) is designed to evaluate a pressure curve of the pressure values ​​of the plurality of pressure sensors (8; 58).

12. Coating device (1; 51) according to claim 11, wherein a plurality of pressure sensors are arranged distributed on a floor and / or distributed in the circumferential direction on an inner wall of the chamber, wherein the control unit (10; 60) is designed to variably control the feed in order to convey a variable, adjustable suspension mass flow into the chamber depending on the pressure profiles measured by the pressure sensors (8; 58).

13. Coating device (1; 51) according to claim 12, wherein the control unit (10; 60) is designed to reduce the suspension mass flow if excessive pressure differences occur between the pressure sensors (8; 58) arranged on the same horizontal plane.

14. Coating device (1; 51) according to claim 12 or 13, wherein the control unit (10; 60) is designed to signal or to reject the substrate body (2) if excessive pressure differences occur between the pressure sensors (8; 58) arranged on the same horizontal plane.

15. Coating device (1; 51) according to one of claims 6 to 14, wherein a plurality of pressure sensors (8; 58) are arranged in different horizontal planes on an inner wall of the chamber (535), wherein the control unit (10; 60) is designed to variably control the feed in order to convey a variable, adjustable suspension mass flow into the chamber (535) depending on the pressure profiles measured by the pressure sensors (8; 58) arranged in different horizontal planes, in particular to set a filling level.

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