A support structure for a heating disc or a heating resistance, a support system and an electric exhaust heater

Abstract

A support structure (70) for a heating disc or heating resistor (10) in an exhaust system, comprising: a multi-part housing (35); at least one first outer ring (40) made of a fibrous material; and at least one second inner ring (80) made of an electrically non-conductive and temperature-resistant material that differs from the fibrous material of the at least one first ring (40); wherein the at least one second inner ring (80) defines a receiving space for the heating disc or heating resistor (10).

Description

Field of invention

[0001] The present invention relates generally to support structures and systems for receiving a heating element with areas of application particularly in exhaust aftertreatment systems. Background of the invention (and prior art)

[0002] With an eye toward upcoming emissions regulations (e.g., Euro 7, CN 7, EU VII, CN VII), automotive manufacturers are constantly seeking technologies for the active thermal management of exhaust aftertreatment systems. The aim is to reduce cold-start emissions while simultaneously keeping the relevant exhaust system components at operating temperature. Electric exhaust heaters, also known as e-heaters, are considered a promising technology in this context, capable of not only meeting future emissions targets but also actively extending the service life of the underlying systems.

[0003] A promising approach here is the use of heating elements with a cellular structure, e.g. square or hexagonal, made of a high-temperature resistant material (e.g. Ni-Cr or Fe-Cr-Al alloy), which offer very good heating performance with a small installation space requirement.

[0004] One challenge, however, is the integration of such a heating element into a metal housing of an exhaust aftertreatment system with the following main requirements: The heating element, for example a heating disc or a heating resistor, must be robustly fixed within the housing for the entire vehicle lifespan, taking into account high exhaust gas temperatures and mass flows, as well as high vibration and acceleration values ​​in both axial and radial directions. Furthermore, electrical insulation must be provided to prevent short circuits or other malfunctions. In addition, thermal insulation from surrounding components and the use of the simplest possible manufacturing processes are required.

[0005] Up to now, a pair of pressed or pre-tensioned rings have been used to attach the heating disc, welded to a slotted tube on both sides of the heating disc.

[0006] However, internal tests of electric heaters constructed in this manner revealed abrasion and erosion, particularly in the pressed rings, during continuous thermoelectric operation. This led to deterioration of the associated support structure and the overall support system, as well as damage to the electric heater itself, and consequently, its failure. The cause of the observed abrasion is believed to lie primarily in the relative movement of the heating disc to the compressed rings. During the compression of the support structure in the electric heater assembly process, some fragments of the rings are pressed into a cellular structure of the heating disc. During operation of the electric heater—accompanied by the expansion and contraction of the heating disc—these fragments can break off and gradually protrude from the metal rings belonging to the housing.

[0007] In this context, reference is made to US 2022 / 0186647 A1, which discloses a heating device with stabilizing elements for an exhaust system, as well as an exhaust system. Furthermore, US 5,597,503 A discloses an axially mounted housing for electric heaters for heating an exhaust gas stream, with a peripheral pressure ring that generates a diametrically balanced force. A heating element is installed in the housing with a one-piece housing wall, the heating element being held between a circumferential support element and a circumferential pressure ring attached to the housing wall. US 6,025,578 A also discloses an electrically insulating bushing with an electrostatic corrosion protection device. Object of the invention

[0008] The object of the present invention is to overcome one or more of the problems or disadvantages associated with the prior art. Summary of the invention

[0009] The aforementioned problem and further problems are solved by a support structure for a heating disc or a heating resistor, a support system, and an electric exhaust gas heater according to the main claims. The dependent claims relate to preferred embodiments of the invention.

[0010] The present invention relates to a support structure for a heating disc or heating element in an exhaust system, comprising: a multi-part housing, at least one first outer ring made of a fibrous material, and at least one second inner ring made of an electrically non-conductive material that differs from the fibrous material of the at least one first ring. The at least one second inner ring defines a receiving space for the heating disc or heating element. The aforementioned arrangement of the support structure has, among other advantages, the structural separation of the at least one first outer ring from the heating disc or heating element in the exhaust system. Such separation helps to reduce wear of the support structure due to thermal and / or mechanical stress during use in the exhaust system.

[0011] The support structure is optionally designed such that the at least one first ring consists of two rings and / or that the at least one second ring consists of two rings, with the receiving space for the heating disc or heating element preferably defined between the two second rings. Such a design can simplify assembly of the support structure as well as its integration into a higher-level structure, depending on the application.

[0012] The multi-part housing in the support structure optionally comprises at least two metal rings or two metal halves, preferably configured to apply a predefined clamping pressure of up to approximately 15 bar to the first and second rings. This pressure is particularly preferably between approximately 2 and 4 bar, depending on the specific application and / or the underlying installation size. The stated values ​​are subject to generally applicable tolerances for components in exhaust system construction, both for metallic housing parts and for ceramic fiber materials in catalyst bearings.

[0013] The fiber material of the at least one first ring of the support structure is optionally a ceramic material, preferably Al2O3, SiO2 or a mullite ceramic material, the latter being a mixture of Al2O3 and SiO2 and more precisely Al2Al 2+2x Si 2-2x O 10-x where x = oxygen vacancies per unit cell.

[0014] The fiber material of at least one first ring of the support structure optionally comprises fibers with a diameter in the range of approximately 3 to 12 µm, preferably 5 to 10 µm. Additionally or alternatively, the fibers of the fiber material are arranged in a length-to-diameter ratio greater than 3:1.

[0015] Furthermore, the at least one first ring or the two first rings of the support structure are optionally compressible, preferably by a factor in the range of 2 to 5 in the installed state.

[0016] The material of the at least one second ring or the two second rings optionally has at least one of the following properties: It is temperature-resistant up to 1100 °C, preferably in a temperature range between -40 °C and 1100 °C. Furthermore, or alternatively, it is compressible, flexible, and / or bendable, wherein the compressibility is preferably lower than that of the material of the at least one first ring and is in the low percentage range, particularly preferably at a maximum of 20%. Furthermore, or alternatively, it is formable, preferably in a ring, oval, or elliptical shape. Optionally, it also exhibits erosion resistance and / or resistance to exhaust gases and / or chemical resistance, preferably to substances that may occur in exhaust aftertreatment systems.

[0017] The material of the at least one or two second rings of the support structure is optionally mica. Preferably, the material of the at least one or two second rings of the support structure is a layered silicate, particularly preferably phlogopite, muscovite, a potassium-magnesium aluminosilicate with optional fluorine or hydroxide ions, a non-organic binder, or a combination thereof. The material can be selected according to the application: Phlogopite, in particular, is especially suitable for applications with extremely hot exhaust gases, for example, in connection with gasoline applications or internal combustion engines, due to its high temperature resistance. Muscovite, in comparison, is suitable for somewhat lower temperature ranges, such as those that can occur in diesel applications.

[0018] At least one of the first and / or second rings of the support structure can optionally be at least two-part in the circumferential direction. Depending on the application, available space, and / or the need for corresponding pre-assembly of the support structure, a symmetrical division, for example at 180° intervals, is preferred. Alternatively, however, an asymmetrical or uneven division is conceivable, whereby only one of the aforementioned rings can be subdivided once or multiple times. A potential influencing factor in this context is, for example, the number and / or arrangement of electrodes on the heating disc or heating resistor used. An independent influencing factor, and thus a technical advantage, can be that retrofitting the support structure according to the invention into an existing support system is also possible due to the appropriately adapted division of the rings.

[0019] Simultaneously or alternatively, at least one of the first and / or second rings can optionally have an L-shaped, U-shaped, round, or rectangular cross-section. This includes any combination of rings and cross-sections that have a corresponding influence on aspects such as the installability or retrofitting of the support structure according to the invention, as well as on economic aspects, for example, with regard to the availability of the raw materials used.

[0020] The at least one second ring or the two second rings of the support structure can optionally be provided as a coating on a corresponding side of the at least one first ring or the respective first ring. Simultaneously or alternatively, the at least one second ring or the two second rings can optionally have a thickness of about 0.1 mm to 1.5 mm, preferably about 0.1 mm to 0.8 mm.

[0021] Furthermore, at least one second ring, or at least one of the two second rings, may optionally have a metal mesh insert.

[0022] In addition, at least one first ring or at least two first rings of the support structure may optionally have a continuous outer contour or alternating circumferential depressions and / or elevations.

[0023] The present invention further relates to a support system for an electric heating device, comprising the following: the support structure according to the invention and a heating disc or heating resistor, preferably with two sides, a cellular structure and / or a plurality of slots. The heating disc or heating resistor is arranged in the receiving space of the at least one second ring or between the two second rings.

[0024] In the support structure or support system according to the invention, the respective first and second rings are optionally pre-assembled, preferably glued or sewn together. Alternatively or simultaneously, the heating disc or heating element is optionally pre-assembled on both sides to the corresponding side of the respective second ring, preferably glued or sewn together. Accordingly, aspects such as dimensional stability and assembly accuracy can be improved in the assembled state. Furthermore, optional pre-assembly of individual components can facilitate the assembly of the support structure or support system according to the invention.

[0025] The support structure or support system can optionally include a plurality of pins for positioning, supporting, and holding the heating disc or heating element, and / or for electrical insulation between sections of the heating disc or heating element (10). The plurality of pins are preferably spacers, and a portion of the spacers is particularly preferably designed as a retaining element positioned in a corresponding recess in the housing, with at least one end of the retaining element being directly mechanically connectable to the housing. Furthermore, at least a portion of the spacers is positioned, preferably clamped, between the two second rings (80). The pins can optionally provide electrical insulation between the sections (meandering heating loops) of the heating disc.

[0026] Furthermore, the at least one second ring or the two second rings of the support system optionally contact only an edge region of the heating disc or heating resistor in the circumferential direction, whereby the edge region is not actively heated. Such a mounting of the heating disc or heating resistor simultaneously allows the heating disc or heating resistor to be slidably mounted or in a sliding fit within the support system during a heating or cooling process.

[0027] The present invention also relates to an electric exhaust gas heater comprising a support system according to the invention and a heater housing, preferably made of metal, which is positioned in an exhaust gas line of an exhaust gas aftertreatment system and is equipped to receive the support system. Brief description of the drawings

[0028] The invention, as well as further details and advantages thereof, are explained below with reference to preferred embodiments and the figures, where identical designations denote identical elements. The figures show: Fig. 1 an isometric view of an electric exhaust heater with two electrodes; Fig. 2 a partially cut-out side view and a top view of an electric exhaust heater; Fig. 3 a sectional view of an electric exhaust gas heater according to a section AA from Fig. 2, as well as a detail view B from this section view; Fig. 4 an assembly according to the invention consisting of an L-shaped first ring and a flat second ring in different views; Fig. 5 a sectional view of the electric exhaust heater according to a section AA from Fig. 2 as well as a detailed view from the section view; Fig.6 a flat second ring according to the invention in two views; Fig. 7 a sectional view of the electric exhaust heater according to a section AA from Fig. 2 as well as a detailed view from the section view. Detailed description of the invention

[0029] In this description, the terms top, bottom, right, and left, as well as similar terms, refer to the orientations or arrangements shown in the figures and serve only to describe the exemplary embodiments. These terms may indicate preferred arrangements but are not to be understood in a restrictive sense.

[0030] Furthermore, the terms “essentially”, “approximately”, “about”, and similar expressions mean that deviations of + / -10%, preferably + / -5%, from the stated value are permissible.

[0031] The following describes the use of multiple rings, for example, at least one first ring, at least one second ring, or metal rings. The term "ring" is a generic term for any component that does not necessarily have to be round. Rather, geometric adaptability to other design parameters is possible and inherent in the term, with particular consideration given to the shape of the housing and / or the heating element used.

[0032] The present description names and the accompanying figures show the use or installation of a heating element in various embodiments of the present invention. The properties mentioned below apply equally to all embodiments, even if they are only shown, illustrated, or specifically described in a round and / or disc-shaped form.

[0033] Fig. Figure 1 shows an isometric view of an electric exhaust gas heater 1, 2, 3 with two electrodes. The illustration also shows a heating element, specifically a heating disc 10, and a multi-part heater housing, although initially only an outer surface 20 is visible. The heating disc 10 has an exemplary configuration with a plurality of slots and two electrodes for power supply, which are preferably attached directly to the heating disc 10, for example by laser welding.

[0034] A heating element, more precisely a heating disc or heating resistor, as used in the present invention, preferably consists of a regular cell or honeycomb structure having differently shaped cells, for example square or hexagonal cells, and / or is made of a high-temperature-resistant material (e.g., Ni-Cr or Fe-Cr-Al alloy) and / or exhibits very good heating performance with a small installation space requirement. The heating element can have a round cross-section and / or be in disc form.

[0035] The heating element can have a plurality of slots, preferably wider than 1 mm, with a width particularly preferably between 1 and 5 mm. Between individual slots of the plurality of slots, there are optionally 2 to 10, preferably 4 to 5, and particularly preferably 3 or even only 2 cells arranged side by side, this number being variable depending on the application, the positioning of the plurality of slots, and / or the required electrical resistance. The individual cells are optionally between 1.2 and 1.3 mm, preferably 1.27 mm, wide. Their wall thickness is in the range of 150 µm. A cell structure used within the scope of the present invention particularly preferably has a cell density between 50 and 400 CPSI (CPSI = cells per square inch), i.e., between 8 and 62 cells per cm². 2Depending on the arrangement of the individual slots on the heating disc, this results, for example, in an arrangement of interconnected cells in meandering heating loops, which are connected to each other at their respective ends and are arranged between the adjacent slots. Such heating loops serve in particular to prevent an electrical short circuit.

[0036] Due to manufacturing processes and / or shape-related factors, depending on the cell and slot structure, the heating discs used in the present invention typically have sharp edges, for example, circumferential sharp edges. Preferred manufacturing methods fall within the field of additive manufacturing techniques, generative manufacturing techniques, and rapid technologies, which are hereinafter also referred to generally as 3D printing processes. However, the support structures, support systems, and / or electric exhaust heaters of the present invention are also compatible with heating discs or resistors manufactured by other means, which makes the present invention also suitable for retrofit systems. Examples of alternative manufacturing methods include extruded heating discs or heating discs made from soldered, welded, or formed thin sheets, as well as cast or stamped heating discs.The thickness of a heating disc used within the scope of the present invention is preferably between 3 and 15 mm, particularly preferably between 4 and 8 mm, although other dimensions are also conceivable depending on the application.

[0037] Fig. Figure 2 is a partially cutaway side view and a top view of an electric exhaust heater 1, 2, 3 with a basic configuration as shown in Fig. 1. Electric exhaust heater 1, 2, 3 shown. In the upper right partial section of the electric exhaust heater 1, 2, 3 of the Fig.Figure 2 shows a pin or pin 60 embedded in the heating disc 10, consisting of a plurality of pins 60. The pins 60 serve to position, support, and / or retain the heating disc or heating resistor 10 in a housing of a support structure (not shown in detail here). The pins 60 are preferably spacers, optionally with a metal core and preferably ceramic-coated, configured to keep sections of the heating disc 10 at a distance. Particularly preferably, at least some of the spacers are designed as retaining elements positioned in a corresponding recess in the housing, with at least one end of the retaining elements being directly mechanically connectable to the housing. They can also fulfill the aforementioned function as spacers by maintaining constant distances between individual segments of the overall arrangement and thereby preventing potential short circuits.

[0038] The top view of the electric exhaust heater 1, 2, 3, shown below the sectional view, again shows the outer surface 20 of the heater housing as well as a cover 50 belonging to the heater housing. Together with an inner surface (not yet shown here), this results in a purely exemplary arrangement that can be adapted depending on the application.

[0039] Fig. Figure 3 shows a sectional view of an electric exhaust gas heater 1 according to a section AA from Fig. 2, as well as a detailed view B from this sectional view. The electric exhaust heater 1 of the Fig. 3 features the heating disc 10. Furthermore, additional housing parts or corresponding divisions may be required, for example, due to installation space, the type and sequence of assembly of the overall arrangement, etc.

[0040] The electric exhaust heater 1 of the Fig.Figure 3 has a support structure 70 according to the invention for the heating disc 10, wherein the support structure 70 comprises the following elements: A multi-part housing 35, shown here in two-part form and preferably made of rings and / or metal. The multi-part housing 35 of the support structure 70, as shown in Fig. 3 shown, can be part of the heating housing of the electric exhaust heater 1, 2, 3 according to Fig. 1. Accordingly, it falls in Fig. 3 an inner side 30 of the heating housing with a side of the housing 35 of the support structure 70 together.

[0041] The support structure 70 from Fig.3 further comprises two first outer rings 40 made of a fibrous material and two second inner rings 80 made of an electrically non-conductive material that differs from the fibrous material of at least the first rings 40. The two inner rings 80 define a receiving space for the heating disc 10. The heating disc 10 is arranged between the two second inner rings 80 in the receiving space of the support structure 70 of the electric exhaust gas heater 1. The two second inner rings 80 are presented here in a flat embodiment. Together with the heating disc 10 and the two outer rings 40, shown here in an L-shape, as well as the two-part housing 35, they form a support system according to the invention for an electric heating device, here by way of example including the heating disc 10. The support structure 70 clamps the heating disc 10 in an edge region of the heating disc 10 that is not actively heated.

[0042] Even if they are not in the section plane of detail view B of the Fig. 3, then a large number of pins 60 can optionally be installed at this point in the support structure 70 or in the support system, as are used in connection with Fig. 2 was described. These pins 60 can then optionally be seated with one end in the metal rings of the support structure 70 or alternatively be pre-tensioned between the second ring(s), as in Fig.Figure 3 shows that the pins are held in position axially by means of the first and second rings 40, 80. At their opposite ends, they are clamped between conductor track sections of the heating disk 10 and the second rings 80 under axial contact. An optional combination of the support structure 70 according to the invention with the plurality of pins 60 can synergistically contribute to improving the durability of the entire arrangement against external influences. Aspects of dimensional stability, wear resistance, and temperature resistance are mentioned here as purely examples.

[0043] Fig. Figure 4 shows an assembly consisting of an L-shaped first ring 40 and a flat second ring 80 in various views. On the right side of the ring combination, one half of the receiving space for the heating disk 10 is indicated.

[0044] Fig.Figure 5 shows a sectional view of a second electric exhaust heater 2 with a basic configuration as shown in Fig. 1, also according to a section AA from Fig. 2. In addition, a detailed view B from the section view is shown.

[0045] In detail, the second electric exhaust heater 2 differs from the Fig. 5 of the first electric exhaust heater 1 of the Fig.3 by the respective shapes of the components of the support structure 70 for the heating disc 10. First, the multi-part housing 35 is also part of the heating housing 20, 30, 50 of the electric exhaust heater 2, although other variants not shown are also possible in which the housing 35 is separate from the heating housing 20, 30, 50. Furthermore, the two first outer rings 40 are not L-shaped, but I-shaped in cross-section. In addition, the two second inner rings 80 are L-shaped in cross-section, with the L opening outwards towards the first ring 40 of each, with which it forms a corresponding assembly. Accordingly, in the electric exhaust heater 2, the receiving space for the heating disc 10 is formed between the two second inner rings 80, into which a heating disc 10 is inserted.

[0046] Fig.Figure 6 shows a second inner ring 80 according to the invention. The ring shown here is flat compared, for example, to a corresponding (not shown) outer ring 40. The ring 80 has a circular outer circumferential edge. It also has an inner circumferential edge with varying diameters, i.e., with oval to ellipsoidal portions. The ring 80 shown is point-symmetrical about the center of the outer circular circumferential edge. As the accompanying detail views A and B show, the ring 80 has a rectangular cross-section and an optional recess in its outer circumference for circumferential positioning. However, such a positioning aid would be unnecessary if the ring 80 also had a circular inner circumferential edge with the same radius at all points. Although such an inner circumferential edge is not shown here, it represents an alternative embodiment of the ring 80 according to the invention.

[0047] Fig.Figure 7 shows a sectional view of a third electric exhaust heater 3 with a basic configuration as shown in Fig. 1, also according to a section AA from Fig. 2. In addition, a detailed view B from the section view is shown.

[0048] In detail, the third electric exhaust heater 3 differs from the Fig. 7 of the first and the second electric exhaust heater 1, 2 of the Fig. 3 and Fig. 5 partly by the shapes, number and arrangement of the components of the support structure 70 for the heating disc 10. In particular, here again, similar to the Fig. 3, two flat second inner rings 80 shown. Between the two second inner rings 80 and the two first outer rings 40, the Fig.7 now describes an embodiment with optional L-shaped rings 90, which are preferably made of metal. An advantage of such a design is that it prevents fibers from escaping the first rings 40 into the heated area of ​​the heating disc 10. Furthermore, such L-shaped rings 90 can be manufactured cost-effectively using common manufacturing processes in the metalworking industry. Generally applicable or not shown features

[0049] Regarding the in the Fig. 3, Fig. 5 and Fig.With regard to the seven variants of the housing 35 shown, as well as the number and shapes of the inner rings 40 and the outer rings 80, it should be noted that other embodiments are conceivable in which any combination of a one-piece or multi-piece housing, a one-piece or multi-piece first ring 40, and a one-piece or multi-piece second ring 80 is possible. The cross-sections and shapes of the individual rings can also vary in this context; for example, ring-shaped outer edges and simultaneously oval inner edges, or vice versa, are possible. Furthermore, the rings do not necessarily have to be round, especially if the inner heating element or the outer heating housing is not round or oval.

[0050] The at least one or the first two rings used in the present invention are made of a fibrous material, preferably a ceramic material. This ceramic material is particularly preferably Al₂O₃, SiO₂, or a mullite ceramic material based on a mixture of Al₂O₃ and SiO₂. The at least one or the first two rings are used, among other things, for positioning or centering the heating disc and preferably have at least one flat surface which, in the assembly described below with at least one second ring, preferably exhibits adequate static friction properties, with a corresponding coefficient of friction in the range between 0.1 and 0.8. The material used is ideally characterized by good compressibility.Depending on the application, a fiber ring can be compressed after installation to half (factor 2) to one-fifth (factor 5), preferably to one-third (factor 3) of its original thickness. For example, a preferred fiber ring has a thickness of approximately 10 to 12 mm before installation, which is compressed, prestressed, pressed together and / or compressed to a thickness of approximately 4 mm during installation.

[0051] Furthermore, only one or the first two outer rings are usually necessary to keep the heating element in its original position despite external influences, such as exhaust gases in the exhaust pipe of an exhaust aftertreatment system. Such influences include, in particular, high operating temperatures, typically between 900 and 1100 °C, and high gas pressure, which can sometimes lead to accelerations of approximately 60 to 70 g, where 1 g = 9.80665 m / s². 2Furthermore, due to their specific material, they act as an insulator between the heating disc and the housing, which helps not only to protect the housing from heat exposure by the heating disc, but also to reduce thermally induced relative movement between individual components. In particular, relative movement between the heating disc and the bearing area is deliberately permitted, despite axial preload. In this context, it is preferred that the heating disc does not come into contact with the housing by using at least one first or the first two outer rings.

[0052] In applications of carrier systems for a heating disc, where the at least one first ring or the first two rings are in direct contact with the heating disc over time, the underlying fibers begin to wear down and / or break, leading to corresponding damage to the at least one first or the first two outer rings and thus, in the long term, to the entire system due to abrasion and / or erosion. This wear can be caused by thermal abrasion, as the heating disc expands and contracts during numerous heating and cooling cycles throughout its use. In particular, an expansion of the heating disc in the radial direction of up to 1.5 mm, measured from the center of the heating disc, is to be expected, given the parameters described above for heating discs usable within the scope of the present invention.A potential expansion of the heating disc in the direction of thickness can therefore be neglected.

[0053] The wear of at least one of the first or the first two outer rings can also be caused by the shape of the heating disc. For example, sharp edges around the perimeter and / or particularly thin wall elements, such as the individual cell walls of the heating structure, contribute to the wear of the first two rings.

[0054] To counteract premature wear and / or destruction of the overall system at this point, the present invention provides for the incorporation of at least one or two additional second inner rings, the material of which differs from that of the at least one first outer ring or the two first outer rings. Preferably, the at least one second or the two second inner rings have a thickness of approximately 0.1 to 0.8 mm. The material of the at least one second or the two second inner rings fulfills the criteria of an electrical insulator, for example, to prevent electrical short circuits. Furthermore, it optionally exhibits high temperature resistance up to approximately 1100 °C, preferably from approximately -40 °C to approximately 1100 °C.In particular, the range of 900 to 1100 °C is especially relevant in the context of high-temperature applications, for example when using a support structure according to the invention installed in electric exhaust heaters for gasoline engines.

[0055] In addition, there is increased mechanical resistance to wear. This increased resistance can be ten times greater or more compared to applications without at least one or two inner rings. Internal comparative tests showed that electric exhaust heaters without an inner ring or with inner rings failed after approximately 3,000 test cycles, while electric exhaust heaters with an inner ring or with inner rings failed after approximately 50,000 test cycles.

[0056] Furthermore, it should exhibit resistance to exhaust gases in general and / or chemical resistance, preferably to substances that may occur in exhaust aftertreatment systems. It should also optionally be easily formable, preferably in ring, oval or elliptical shapes, and / or erosion-resistant.

[0057] The material used for one or the two second inner rings can be, for example, mica (also known as mica in international terminology), preferably a layered silicate, particularly preferably phlogopite, muscovite, a potassium magnesium aluminosilicate with optional fluorine or hydroxide ions, a non-organic binder, or a combination thereof. The material used can be of natural origin or artificially produced using suitable processes. The advantage of artificially produced materials is, for example, that desired material properties can be achieved in a targeted manner while simultaneously avoiding impurities. Of particular note in this context is the improved temperature resistance of synthetic mica material compared to naturally derived mica, i.e., at temperatures up to 1000°C during long-term operation.

[0058] In this context, Table 1 shows, using an example, various criteria, standards to be met, and some corresponding value ranges: Table 1 Material properties basic material structure Phlogopit Temperature range during continuous operation IEC 60371-2 [°C] < 1000 °C Temperature range during intermittent Operation IEC 60371-2 [°C] Density DIN 28090-2 [g / cm 3 ] 1,8 Pressure resistance at 300 °C DIN 52913 [N / mm 2 ] 32 Compression ASTM F 36 J [%] 20 Rebound [%] 35 Cold compression coefficient εKSW DIN 28090-2 [%] 12 Cold recovery value εKRW [%] 3 Warm setpoint εWSW / 300 [%] 10 Hot reshaping value εWRW / 300 [%] 2 Tensile strength transverse DIN 52910 [N / mm 2 ] 25 Flexural strength ISO 178 [N / mm 2 ] Dielectric strength at 23 °C IEC 243 [kV / mm] 19 Electrical conductivity [S / cm] 1,0 × 10 -14 Insulation resistance at 550°C IEC 60093 [Ohm / cm] Thermal conductivity (vertical) at 23 °C [W / (m K)] 0,07 Thermal expansion (perpendicular to the layer) [1 / 10 6 K] Thermal expansion (horizontal to the layer) [1 / 10 6 K] Burn test ASTM SAE J369 non-flammable Mica content IEC 60371-2 [%] Binder content IEC 60371-2, e.g. silicone resin [%] Weight reduction according to DIN 52911 [%] Heat resistance for 2 hours up to 800°C (Thickness swelling) Maximum pressure bear Absorbency ISO 62 [%] Tolerances according to DIN 28091-1 Formats [mm] 1200 × 1000 0,5 / 0,8 / 1,0 / 1,5 / 2,0 / 3,0 / 4,0 Thickness [mm] / 5,0

[0059] While Table 1 shows a specific example of material for at least one or the two second inner rings, other materials are also conceivable, especially when it comes to the aspect of temperature resistance above 1000 °C, particularly in continuous operation.

[0060] Due to their specific positioning, where, for example, a first outer ring or ring part is arranged between an outer part of the housing and a second inner ring or ring part, the second ring or its ring part(s) interact with the heating disc and the two first ring(s) in the support structure according to the invention, acting as a separating layer or separating structural elements to improve the abrasion resistance of the overall assembly. Increased abrasion resistance of the support structure reduces wear on the overall assembly, which in turn extends its service life and thus its usability.

[0061] Alternatively, the two second rings can be provided not as separate components, but as a coating on the corresponding side of the two first rings. Furthermore, all rings—whether one, two, three, or all four—can optionally be multi-part. Additionally, all rings, or even just some of the rings used, can optionally have an L-shaped, U-shaped, round, or rectangular cross-section instead of a true ring. This includes all combinations of rings and cross-sections that have a corresponding influence on aspects such as the ease of installation or retrofitting of the support structure according to the invention, as well as on economic aspects, for example, with regard to the availability of the raw materials used.The choice of ring shape can depend, for example, on whether the edges of the first rings should also be protected by the second rings, and / or whether edges of the heating disc come into contact with areas or parts of the first rings and should be protected from abrasion / heat by the second rings. In addition to the already described and shown shapes, another variant should be mentioned in which the first outer ring is U-shaped and a single piece. This allows for combination with either two inner rings, of which different shapes are possible, or with just one U-shaped, single-piece inner ring.

[0062] During the assembly process, the first and second rings can be installed as separate components. Alternatively, the respective first and second rings can be pre-assembled, preferably by gluing or sewing. Alternatively or additionally, the second rings can also be pre-assembled to the corresponding side of the heating element, preferably by gluing or sewing.

[0063] In all the aforementioned embodiments, the rings, in particular the at least one first ring and the two first outer rings, are optionally pre-tensioned or compressed axially to a predefined degree in order to withstand the external operating conditions. In this context, homogeneous compression and / or fixation of the heating disc over its entire circumference must be ensured. The pressure applied here preferably reaches up to 15 bar. Particularly preferably, this pressure is approximately 2 to 4 bar, depending on the specific application and / or the underlying installation size, plus generally applicable tolerances.

[0064] In addition to the wear mechanisms already mentioned, fiber creep of the first two rings was also observed, caused by swelling and expansion towards the center of the heating disc. To further reduce this creep risk, the outer contour of the first two rings can be modified to create more clearance between the housing and the support structure. Instead of a constant outer diameter, the first two rings can, for example, have alternating circumferential depressions and protrusions. The number of protrusions can optionally vary and depend on the size of the heating disc or its diameter. Such a design optionally results in even further improved durability compared to known solutions, thereby increasing product lifespan and preventing customer complaints.

[0065] The invention has been described with reference to preferred embodiments, whereby the individual features of the described embodiments can be freely combined and / or exchanged, provided they are compatible. Likewise, individual features of the described embodiments can be omitted if they are not essential. Numerous modifications and embodiments are possible and obvious to a person skilled in the art without departing from the inventive concept. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2022 / 0 186 647 A1

[0007] US 5 597 503 A

[0007] US 6 025 578 A

[0007]

Claims

[1] A support structure (70) for a heating disc or a heating resistor (10) in an exhaust system, comprising: a multi-part housing (35); at least one first outer ring (40) made of a fiber material; and at least one second inner ring (80) made of an electrically non-conductive and temperature-resistant material which is different from the fiber material of the at least one first ring (40); wherein the at least one second inner ring (80) defines a receiving space for the heating disc or the heating resistor (10). [2] The support structure (70) according to claim 1, wherein the at least one first ring (40) is two rings and / or wherein the at least one second ring (80) is two rings; wherein the receiving space for the heating disc or the heating resistor (10) is preferably defined between the two second rings (80). [3] The support structure (70) according to claim 1 or 2, wherein the multi-part housing (35) comprises at least two metal rings or two metal halves, which are preferably configured to apply a predefined clamping pressure of up to about 15 bar to the first and second rings (40, 80). [4] The support structure (70) according to any one of the preceding claims, wherein the fiber material is a ceramic material, preferably Al2O3, SiO2 or a mullite ceramic material made of Al2O3 and SiO2. [5] The support structure (70) according to any one of the preceding claims, wherein the fiber material comprises fibers having a diameter in the range of approximately 3 to 12 µm, preferably 5 to 10 µm; and / or wherein the fibers of the fiber material are present in a length to diameter ratio of > 3 to 1. [6] The support structure (70) according to any one of the preceding claims, wherein the at least one first ring (40) is compressible or the two first rings (40) are compressible, preferably by a factor in the range of 2 to 5 in the installed state. [7] The support structure (70) according to any one of the preceding claims, wherein the material of the at least one second ring (80) or the two second rings (80) has at least one of the following properties: temperature resistant up to 1100 °C, preferably in a temperature range between -40 °C and 1100 °C; compressible, flexible and / or pliable; malleable, preferably in ring, oval or elliptical shape; erosion-resistant; resistant to exhaust gases; and chemically resistant, preferably against substances that can occur in exhaust aftertreatment systems. [8] The support structure (70) according to any one of the preceding claims, wherein the material of the at least one second ring (80) or the two second rings (80) is mica, preferably a layered silicate, particularly preferably phlogopite, muscovite, a potassium magnesium aluminosilicate with optional fluorine or hydroxide ions, a non-organic binder or a combination thereof. [9] The support structure (70) according to any one of the preceding claims, wherein at least one of the first and / or second rings (40, 80) is at least two-part in the circumferential direction; and / or wherein at least one of the first and / or second rings (40, 80) has an L-shaped, U-shaped, round or rectangular cross-section. [10] The support structure (70) according to one of the preceding claims, wherein the at least one second ring (80) or the two second rings (80) are present as a coating on a corresponding side of the at least one first ring (40) or the respective first ring (40); and / or wherein the at least one second ring (80) or the two second rings (80) have a thickness of approximately 0.1 mm to 1.5 mm, preferably approximately 0.1 mm to 0.8 mm. [11] The support structure (70) according to any one of the preceding claims, wherein the at least one second ring (80) or at least one of the two second rings (80) comprises a metal mesh insert. [12] The support structure (70) according to one of the preceding claims, wherein the at least one first ring (40) or the at least two first rings (40) have a continuous outer contour; or wherein the at least one first ring (40) or the two first rings (40) have alternating circumferential depressions and / or elevations. [13] A support system for an electric heating device comprising: the support structure (70) according to one of the preceding claims; and a heating disc or a heating resistor (10), preferably with two sides, a cellular structure and / or a plurality of slots; wherein the heating disc or the heating resistor (10) is arranged in the receiving space of the at least one second ring (80) or between the two second rings (80). [14] The support structure (70) according to any one of claims 1 to 12 or the support system according to claim 13, wherein the respective first and second rings (40, 80) are pre-assembled, preferably glued or sewn together; and / or wherein the heating disc or the heating resistor (10) is pre-assembled on both sides to the corresponding side of the respective second ring (80), preferably glued or sewn. [15] The support structure (70) according to any one of claims 1 to 12 or 14, or the support system according to any one of claims 13 or 14, further comprising: a plurality of pins (60) arranged for positioning, supporting, holding the heating disc or the heating resistor (10) and / or for electrical insulation between partial regions of the heating disc or the heating resistor (10); wherein the plurality of pins (10) are preferably spacer elements; wherein particularly preferably a part of the spacer elements is designed as holding means which are positioned in a corresponding recess in the housing (35), wherein at least one end of the holding means is mechanically connectable directly to the housing (35); and / or wherein at least some of the spacer elements are positioned, preferably clamped, between the two second rings (80). [16] The carrier system according to one of claims 12 to 15, wherein the at least one second ring (80) or the two second rings (80) contact only an edge region of the heating disc or the heating resistor (80) in the circumferential direction, wherein the edge region is not actively heated. [17] An electric exhaust gas heater comprising: the carrier system according to one of claims 12 to 16; a heater housing (20, 30, 50), preferably made of metal, which is positioned in an exhaust line of an exhaust gas aftertreatment system and is adapted to receive the carrier system (70).

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