Method and device for partial removal of catalytic coatings on electric heating elements - Patents.com

Abstract

To provide a method and a device for removing an unwanted catalyst coating.SOLUTION: A method for partially removing a catalyst coating of an electric heating element includes the steps of: providing an electric heating element 1 coated with a catalyst coating; positioning the heating element between a first holding element 101 and a second holding element 102, thereby making a first end face 10 of the heating element face the first holding element, making a second end face 11 of the heating element face the second holding element, and fixing the heating element by the two holding elements; covering the two end faces with the holding elements, and thereby keeping outside regions 20, 21 and 22 formed into delayers uncovered; rotating the two holding elements and the heating elements positioned therebetween around a rotary shaft 105, and applying a delayer medium in a region formed in the delayers; and stopping the application of the delayer medium and the rotation of the heating element, and releasing the heating element when the coating is removed in the region formed into the delayers.SELECTED DRAWING: Figure 2c

Description

[Technical field]

[0001] The present invention relates to a catalyst for electric heating elements. film Partial Demembrance The present invention relates to a method and device for [Background technology]

[0002] In motor vehicles with combustion engines, exhaust gas aftertreatment is necessary to comply with legally mandated exhaust gas standards. The components of the exhaust gas aftertreatment device provided for the aftertreatment of the exhaust gases, such as catalytic converters and particle filters, should reach the so-called "light-off" temperature (= the "light-off" temperature of the components of the exhaust gas aftertreatment device) as soon as possible after a cold start of the engine in order to ensure effective aftertreatment of the emission-heavy exhaust gases.

[0003] In order to provide the fastest possible heating of the components of the exhaust aftertreatment device after a cold start of the combustion engine, in particular the at least one catalytic converter and the at least one particulate filter, one or more electric heating elements arranged in the direction of the exhaust flow can be arranged upstream of the exhaust aftertreatment components, which can transfer thermal energy converted from electrical energy to the exhaust flow, thereby heating the downstream exhaust aftertreatment components.

[0004] Alternatively, the electric heating element itself may be provided with a catalyst made of a ceramic material. film This catalyst can be provided. film makes the electric heating element a self-heating exhaust after-treatment component during operation, such as a heated catalytic converter of an exhaust after-treatment device.

[0005] Metal housings surrounding the heating elements, especially sheet metal housings, are often used to hold catalysts. film To accommodate an electric heating element having a ceramic catalyst coatingCorresponding contact surfaces are required that do not include, for example, those that allow the electric heating element to expand without stress during heating in its "floating" bearing in the housing. However, film If residues are present at these contact locations, they increase the friction of the "floating" bearings in an undefined manner, such that the heating element may jam under certain circumstances due to blocked thermal expansion in the metal housing. In a worst case scenario, this may lead to an electrical short circuit, which may break down and thus disable the electric heating element.

[0006] Therefore, in general, the catalyst is already present during the manufacturing process of the electric heating element. film By appropriately masking the areas to be excluded from film During the process Covering However, attempts are made to prevent this. Covering Depending on the geometry of the components to be masked, this is not always possible. Particularly in the edge regions of the masking, e.g. film The material also enters the fluid flow channels or fluid flow cells located therein, which are only partially masked. Covered For example, if a tortuous slit in the heating element or other mask irregularities are present along the masking edge, the remaining liquid located there may be lost. film The material penetrates beneath the masking.

[0007] film After drying, the catalyst was infiltrated under the masking. film The material must be removed very precisely mechanically using grinding devices or wire brushes. From an economic point of view, in this case film should only be fully exposed in easily accessible areas of the electric heating element. Demembrance It is possible. film Most of the catalyst remains on the components in less easily accessible areas of the heating element. film is conductive and unacceptable filmThis is disadvantageous in electric heating elements used in exhaust aftertreatment devices in that it can result in an electrical short circuit between the electrical contacts and the heating area of ​​the electric heating element. Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a method for the preparation of a catalytic converter for an electric heating element. film of Demembrance and providing a method and device for heating a heating element that is not required for a particular region of the heating element. film in a particularly simple and effective way. Demembrance It is possible. [Means for solving the problem]

[0009] The solution to this task is a catalyst for an electric heating element having the features according to claim 1. coating Partial Demembrance With regard to the device, the object is to provide a method for the catalytic conversion of an electric heating element having the features of claim 7. film Partially Demembrance This is achieved by a device for determining whether a signal is received from a sensor or a sensor array.

[0010] Catalysis of electric heating elements film Partial Demembrance The method of the present invention for -catalyst film in Covering providing an electrically heated element; - positioning the heating element between a first holding element and a second holding element such that a first end surface of the heating element faces the first holding element and a second end surface of the heating element faces the second holding element and fixing the heating element by means of the two holding elements, the holding elements holding the two end surfaces together cover So, Demembrance Only the outer area is Not covered Steps remain the same, - rotating two holding elements and a heating element positioned between the two holding elements about a first axis of rotation; Demembrance In the area Demembrance applying a medium; - Demembrance Stop application of media and rotation of heating element; film but Demembrance and releasing the heating element when the heating element is removed from the area to be treated.

[0011] The method of the present invention comprises providing a heating element having a plurality of electrodes, each of which is located at an outer edge region of two opposite ends of the electric heating element; Demembrance Catalyst for electric heating elements in the area to be heated film This allows for the direct partial removal of

[0012] To fix the heating element, the preferred embodiment proposes that the holding elements move towards the heating element located between them and fix the centrally located heating element with a defined force. In particular, this allows a clamp-activated, central fixing of the electric heating element between two holding elements with a defined force, which fixing can be advantageously achieved without additional tools.

[0013] In one embodiment, the jet nozzle Demembrance in the area of ​​the heating element that will be Demembrance In particular, such a jet nozzle provides the ability for a medium to be applied. Demembrance In the area of ​​the electric heating element film This gives rise to the ability to precisely remove

[0014] A preferred embodiment can provide that the jet nozzle is moved in a defined pivot range around a pivot axis extending perpendicular to the common axis of rotation of the two holding elements. This allows Demembrance Catalyst in the area of ​​the heating element to be heated film A uniform removal of the

[0015] In a particularly preferred embodiment, the dry ice is DemembranceThe use of dry ice, which is solid carbon dioxide (or CO2 for short), is proposed as a medium for Demembrance In the area of ​​the electric heating element coating The localized removal of the SiO2 layer is therefore abrasive and by thermal shock embrittlement, i.e. film This is particularly advantageous since both can occur due to thermal stresses between the heating element and the heating element. Demembrance After handling, dry ice changes directly from a solid to a gaseous state by sublimation, and therefore does not adopt a liquid phase state between these two phases. Demembrance The use of dry ice as a medium is Demembrance The heating element in the area to be removed coating It has the further advantage of being free of impurities.

[0016] Preferably, the method can be partially automated or fully automated in particularly advantageous embodiments.

[0017] Catalyst in the area of ​​the electric heating element film of Demembrance A device according to the invention for carrying out the method, in particular for carrying out the method according to any of claims 1 to 6, a first holding element and a second holding element, between which a heating element can be placed, the holding elements fixing the heating element positioned between the holding elements and holding two opposite end faces of the heating element; cover So, Demembrance Only the outer area is Not covered a first retaining element and a second retaining element, a drive device adapted to drive a common rotational movement of the two holding elements and of a heating element fixed by the two holding elements around an axis of rotation; -For heating elements Demembrance and a means for applying the medium.

[0018] The method of the present invention comprises providing a heating element having a plurality of electrodes, each of which is located at an outer edge region of two opposite ends of the electric heating element; Demembrance Catalyst for electric heating elements in the area to be heated filmThe device can in particular be adapted for partially automated operation or, in a particularly advantageous embodiment, can be fully automated.

[0019] One embodiment comprises: Demembrance A means for applying a medium to the heating element, Demembrance In the area Demembrance It is proposed that the dry ice be adapted for use as a medium. Demembrance The advantages of using it as a medium have already been explained above.

[0020] One embodiment comprises: Demembrance The means for applying the medium to the heating element provides the ability to include a jet nozzle. In particular, the jet nozzle comprises: Demembrance In the area of ​​the electric heating element film This gives rise to the ability to precisely remove

[0021] A preferred embodiment proposes that the jet nozzle is adapted such that it is movable in a defined rotational range around an axis of rotation that extends perpendicular to the common axis of rotation of the two holding elements. As a result, the catalytic converter is heated in the region of the electric heating element. coating By removing the smallest areas, Demembrance It can be done.

[0022] Further characteristics and advantages of the present invention will become apparent from the following description of examples of preferred embodiments with reference to the attached drawings, which are shown below. [Brief description of the drawings]

[0023] [Figure 1a] FIG. 1 is a schematic highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a plan view. [Figure 1b] FIG. 1 is a schematic highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a plan view. [Figure 1c] FIG. 1 is a schematic highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a plan view. [Figure 1d] FIG. 1 is a schematic highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a plan view. [Figure 2a] FIG. 1b shows a schematic and highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a side view rotated by 90° with respect to FIG. 1a. [Figure 2b] FIG. 1b shows a schematic and highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a side view rotated by 90° with respect to FIG. [Figure 2c] FIG. 1c shows a schematic and highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a side view rotated by 90° with respect to FIG. [Figure 2d] FIG. 1c shows a schematic and highly simplified representation of a method and device for partial stripping of a catalytic coating of an electric heating element in a side view rotated by 90° with respect to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 1a and 2a, in a first method step S1 an electric heating element 1 intended for use in an exhaust aftertreatment device of a combustion engine is provided. This electric heating element 1 is substantially cylindrical in shape and has a ceramic catalyst film 2. FIG. 1a shows the catalyst film Figure 2a shows an electric heating element 1 in plan view having square shaped individual fluid flow passages or fluid flow cells through which the hot exhaust gases of an internal combustion engine flow during operation. Figure 2a shows the electric heating element 1 in a side view rotated by 90° with respect to Figure 1.

[0025] In order to accommodate this electric heating element 1 in a metal housing, in particular a sheet metal housing, which surrounds the heating element 1, a ceramic catalyst film2. These contact surfaces, for example, allow stress-free expansion of the electric heating element 1 during heating in its "floating" bearing. However, coating If residues are present at these contact locations, they increase the friction of the "floating" bearings in an undefined manner, such that the heating element 1 may, under certain circumstances, become jammed due to blocked thermal expansion in the metal housing. In a worst case scenario, this could lead to an electrical short circuit, which would be destroyed, thus rendering the electric heating element 1 unusable.

[0026] This catalyst for electric heating element 1 film 2 is a partial heat exchanger of the electric heating element 1 Demembrance occurs, the device 100 being provided and adapted for this purpose in a manner described below.

[0027] Catalyst for electric heating element 1 film Partial removal of 2 ( Demembrance The device 100 for the heating element 1 comprises a first holding element 101 and a second holding element 102, between which the heating element 1 is positioned in a second method step S2 (FIGS. 1b and 2b) so that a first end face 10 of the heating element 1 faces the first holding element 101 and a second end face 11 of the heating element 1 faces the second holding element 102. The two end faces 10, 11 of the heating element 1 have a substantially circular shape. The holding elements 101, 102 Demembrance Only the outer regions 20, 21, 22 are Not covered One of the two end faces 10, 11 of the heating element 1 is cover Therefore, DemembranceThe areas 20, 21, 22 to be clamped are located on the outer edges of the two end faces 10, 11 of the heating element 1. The holding elements 101, 102 are moved towards the heating element 1 positioned between them and clamp the centrally positioned heating element 1 by a defined force F. The heating element 1 is thus clamped by clamping between the two holding elements 101, 102 with circular clamping surfaces. film The two regions are protected under retaining elements 101, 102 respectively.

[0028] In method step S3 (figures 1c and 2c), the device 100 further comprises a drive device 103 adapted to drive a common rotational movement of the two holding elements 101, 102 and thus of the heating element 1 fixed by and positioned between the latter. The rotation axis 105 extends orthogonally to the end faces 10, 11 of the heating element 1.

[0029] The device 100 also rotates the electric heating element 1 during its rotational movement. Demembrance The areas 20, 21, and 22 film 2. For removing Demembrance It comprises a jet nozzle 104 adapted to apply the medium. As can be seen in particular in Fig. 2c, the jet nozzle 104 can be moved in a pivoting range from a first position to a second position (and vice versa) about a pivoting axis extending perpendicular to the common rotation axis 105 of the two holding elements 101, 102.

[0030] The jet nozzle 104 is directed towards the heating element 1 in a defined path of movement, Demembrance By applying the medium film Remove 2, Demembrance During processing, the heating element 1 gradually swings over the edge area. film 2 is reliably and easily removed in the areas 20, 21, 22 of the heating element 1, down to the smallest area Demembrance will be done.

[0031] Dry ice, i.e., solid carbon dioxide (CO2), is preferably Demembrance The regions 20, 21, 22 of the electric heating element 1 are film 2 by localized removal abrasively and by thermal shock embrittlement, i.e. film 2 and the heating element 1, it is generated by thermal stresses between Demembrance After the jet stripping operation, dry ice changes directly from the solid to the gas phase state by sublimation, and therefore does not adopt a liquid phase state between these two phases. Demembrance The use of dry ice as a medium is Demembrance The heating element 1 is removed in the areas 20, 21, 22. film 2 has the further advantage of being free of impurities.

[0032] The jet nozzle 104 is Demembrance The regions 20, 21, 22 of the electric heating element 1 are film After the holding elements 101, 102 have been completely removed, the rotation is stopped. Similarly, the rotation of the holding elements 101, 102 is stopped. The holding elements 101, 102 then move apart, releasing the heating element 1 positioned between them so that the heating element 1 can be removed from the device (method step S4).

[0033] Completely after the end of the method Demembrance The separated areas 20, 21, 22 allow a defined and reproducible mounting of the heating element 1 in particular in a metal housing, in particular a housing made of sheet metal.

[0034] The device 100 is preferably adapted such that the insertion and removal of the heating element 1 and the movement movements of the holding elements 101, 102 are at least performed automatically. The common rotational movement of the two holding elements 101, 102 and the control of the movement and the pivoting movement of the jet nozzle 104 can also advantageously be automated. The method presented here can therefore be partly automated or, particularly advantageously, fully automated.

Claims

1. A method for partial stripping of a catalytic coating (2) of an electric heating element (1) for use in an exhaust aftertreatment device of a combustion engine, comprising: The electric heating element (1) has a substantially cylindrical shape and has a first end face (10) and a second end face (11) having a substantially circular shape; - providing said electric heating element (1) coated with said catalytic coating (2); - positioning said heating element (1) between a first retaining element (101) and a second retaining element (102), said first end face (10) facing said first retaining element (101) and said second end face (11) facing said second retaining element (102), and fixing said heating element (1) by said two retaining elements (101, 102), said retaining elements (101, 102) covering said two end faces (10, 11) so that only the outer areas (20, 21, 22) to be stripped remain uncovered; - rotating the two holding elements (101, 102) and the heating element (1) positioned between them about an axis of rotation (105) and applying a decoating medium to the outer areas (20, 21, 22) to be decoated; - stopping the application of the decoating medium and the rotation of the heating element (1) and releasing the heating element (1) when the catalytic coating (2) has been decoated in the outer regions (20, 21, 22).

2. 2. The method according to claim 1, characterized in that the holding elements (101, 102) fix the heating element (1) by moving towards the heating element (1) positioned between them and fix the heating element (1) in a central position with a defined force (F).

3. 3. The method according to claim 1 or 2, characterized in that the decoating medium is applied to the outer area (20, 21, 22) to be decoated by means of a jet nozzle (104).

4. 4. The method according to claim 3, characterized in that the jet nozzle (104) is moved in a defined pivot range around a pivot axis extending perpendicular to the rotation axis (105) of the two holding elements (101, 102).

5. 2. The method of claim 1, wherein dry ice is used as the stripping medium.

6. 2. The method according to claim 1, characterized in that the method is partially automated or fully automated.

7. A device (100) for carrying out the method according to claim 1, comprising: a first holding element (101) and a second holding element (102) between which the heating element (1) can be placed, the first holding element (101, 102) fixing the heating element (1) positioned between them and covering two opposite end faces (10, 11) of the heating element (1) so that only the outer areas (20, 21, 22) to be delaminated remain uncovered, a drive device (103) adapted to drive a common rotational movement of said two holding elements (101, 102) and of said heating element (1) fixed by said two holding elements (101, 102) around an axis of rotation (105); - means for applying a descaling medium to said heating element (1).

8. 8. The device (100) according to claim 7, characterized in that the means for applying a descaling medium to the heating element (1) are adapted to apply dry ice as a descaling medium to the outer areas (20, 21, 22) to be descaled.

9. 8. The device (100) according to claim 7, characterized in that the means for applying a decoating medium to the heating element (1) comprise a jet nozzle (104).

10. 10. The device (100) according to claim 9, characterized in that the jet nozzle (104) is adapted to be movable in a defined pivot range around a pivot axis extending perpendicular to the rotation axis (105) of the two holding elements (101, 102).

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