Electric heating device for heating an exhaust gas stream

Abstract

An electric heating device (1) for heating an exhaust gas stream is proposed, comprising a housing (2) containing an electric heating element (100; 200) and at least one support rod (20) connected to the heating element (100; 200), the support rod having two opposing ends arranged on the housing (2). The support rod (20) is movably mounted at at least one of its ends in a sliding bearing (30) to compensate for thermally induced deformation of the support rod (20), the sliding bearing (30) being rigidly connected to the housing (2). The heating device (1) can be used in an exhaust system, e.g., the exhaust system of a motor vehicle, which must be able to handle mass flows exceeding 600 kg / h.

Description

[0001] The present patent relates to an electric heating device for heating an exhaust gas stream. The heating device can be intended for use in an exhaust system, e.g., the exhaust system of a motor vehicle, which must, in particular, be able to handle mass flows of over 600 kg / h.

[0002] Such exhaust systems can be used in motor vehicles with internal combustion engines to purify the exhaust gases released into the environment by the engine. These systems are known as vehicle catalysts. For this purpose, the exhaust gases to be purified must be brought to a working temperature, which is typically achieved by using a heating device located in the exhaust system. The heating device can be an electric heating device, i.e., a heating device in which, by applying an electrical voltage to an electrically conductive heating element, the heating element converts the electrical energy into heat and transfers this heat, for example, to the exhaust gas flowing around and / or through the heating element.

[0003] A particular challenge in the design of heating devices for heating an exhaust gas flow is that, on the one hand, they must transfer heat to the exhaust gas flow particularly efficiently and, on the other hand, they must withstand mechanical stresses such as thermal expansion, vehicle vibrations and / or the flow pressure of the exhaust gas flow, especially at high mass flows.

[0004] The present invention is based on the object of proposing an alternative and / or improved electric heating device, wherein the improvement lies in particular in addressing at least one of the aforementioned challenges.

[0005] According to the invention, this object is achieved by an electric heating device having the features of the main claim. Possible embodiments and further developments are set out in the subclaims and the following description.

[0006] The proposed electric heating device for heating an exhaust gas stream comprises a housing, an electric heating element accommodated in the housing, and at least one support rod connected to the heating element, having two opposite ends arranged on the housing. The support rod is movably mounted at at least one of its ends in a sliding bearing to compensate for a thermally induced deformation of the support rod, with the sliding bearing being rigidly connected to the housing.

[0007] The arrangement of the support rod and plain bearing in the housing can provide thermally compensating support for the heating element, so that the heating element is supported particularly efficiently and the exhaust gas flow and its heating are disrupted as little as possible. During operation, the heating device is usually subject to thermally induced deformations, in particular of the heating element and the support rod connected to the heating element. In particular, the arrangement of the support rod and plain bearing can compensate for thermally induced expansion, contraction, or any other movement of the support rod, especially in its longitudinal direction, since a surface of the support rod and an inner surface of the plain bearing firmly connected to the housing, for example, resting on the surface of the support rod, can be displaced relative to one another. This can reduce undesirable thermally induced movement of the heating element in the housing.

[0008] In the housing, the exhaust gas flow can be directed from an inlet, in particular a housing inlet, to an outlet, in particular a housing outlet. An axial direction in which the exhaust gas flow flows through the housing can be defined between the inlet and outlet.

[0009] The support rod can be mounted at each end in a sliding bearing to compensate for thermally induced deformation of the support rod, with both sliding bearings being rigidly connected to the housing. The sliding bearings can be constructed and arranged identically. By having sliding bearings at both ends of the support rod, thermally induced deformation of the support rod can be compensated more evenly, thus minimizing warping of the heating element in the housing.

[0010] The support rod can extend transversely and in particular orthogonally to an axial direction of the housing in which the exhaust gas flow flows through the housing. The support rod can extend between two opposite sides of the housing and in particular through the housing. The support rod can be arranged parallel to the heating element. The support rod can be arranged in the direction of the exhaust gas flow, i.e. downstream, in front of or behind the heating element. In particular, its arrangement downstream of the heating element can be advantageous, since this reduces heat outflow of the exhaust gas that has not yet passed through the heating element and is therefore relatively cold, and increases the durability and stability of the heating device.The support rod can have a round, in particular circular, or a rectangular cross-section, in particular with two long and two short sides, wherein the long sides can extend along the axial direction of the housing. The support rod can be straight, in particular continuously straight, or curved. The curvature can be concave relative to the housing, i.e. the support rod can be curved in a direction orthogonal to the exhaust gas flow towards the center of the housing. Such a curvature can, for example, improve the mechanical stability of the support rod and heating element. It should be selected such that problem-free mobility of the support rod in the plain bearing is possible, in particular without wedging.

[0011] In principle, several support bars can be provided, i.e. at least two and / or a maximum of six or a maximum of four, in particular identically constructed, support bars. The number, shape, and / or dimensions of the support bars can be selected such that a sufficient support structure is formed for the heating element, e.g., one that is mechanically resistant to the mass flow of the exhaust gas, while at the same time shielding the heating element as little as possible from the exhaust gas flow, as is the case, for example, for a support bar with a circular or rectangular cross-section with two long sides running in the axial direction and two short sides orthogonal to them. If several support bars are provided, they should be spaced apart from one another in such a way that a direct current flow - even through arcing - between the support bars is not possible. The support bars can also be arranged parallel to one another and / or at the same distance from the heating element.

[0012] The support rod can be electrically and / or thermally insulated from the housing, particularly by means of the plain bearing. This prevents unwanted current leakage (bypass) or heat loss. In particular, the heating element can be heated in a targeted and efficient manner.

[0013] The support rod can be arranged in the sliding bearing by means of a clamp, wherein a resulting clamping force exerted on the support rod by the clamp is designed to prevent unintentional displacement and / or vibration of the support rod in the sliding bearing during intended use of the electric heating device, e.g., when the heating device is installed as part of an exhaust system in a vehicle. In other words, the support rod can be non-positively connected to the sliding bearing. The clamping force or non-positive connection can be selected such that, on the one hand, a thermally induced relative movement between the support rod and the sliding element is possible, and, on the other hand, vibration or unintentional displacement of the support rod as a whole is avoided.

[0014] The plain bearing can comprise an outer casing that surrounds the support rod, in particular completely circumferentially. The support rod can therefore be received at its corresponding end in a recess of the plain bearing that is defined by the outer casing. The recess and support rod can be arranged in alignment with one another. In other words, the recess can extend in the same direction as the support rod received therein and thereby form a sliding fit receptacle for the support rod, so that the most uniform compensation possible can be provided without wedging of the support rod and the plain bearing. The outer casing can comprise or consist of two opposing casing halves. The two casing halves allow the required clamping force to be adjusted particularly easily. The plain bearing can comprise an electrically and / or thermally insulating layer arranged between the outer casing and the support rod.For example, the insulating layer can provide electrical and / or thermal insulation between the support rod and the housing. The insulating layer can be elastic, which makes it easier to adjust the required clamping force. The insulating layer can comprise or consist of a needle-like polycrystalline fiber mat, a ceramic, particularly aluminum oxide ceramic, material, and / or a glass fiber-reinforced ceramic composite material. Optionally, one of the two jacket halves can at least partially overlap the other jacket half in the circumferential direction of the support rod. This can be particularly advantageous in combination with a support rod having a circular cross-section, as this makes it easier to adjust the compression of the insulating layer, particularly of an elastic insulating layer. On the other hand, the desired clamping force can also be adjusted by selecting the thickness of the insulating layer.Overlapping of the sheath halves is then unnecessary. The insulation layer can be arranged directly adjacent to the support rod and / or the outer sheath.

[0015] The support rod can be connected to the heating element at a single contact point. This can prevent unwanted current leakage. The support rod can be firmly connected to the heating element, particularly by a material bond. The connection should be as thermally resistant as possible when the heating device is used as intended. The connection can be a welded joint, particularly a laser-welded joint. The support rod can be made of metal or comprise a metal. The metal can, in particular, be or comprise a high-alloy stainless steel, such as 1.4301, or a NiCr alloy. These materials are particularly temperature-resistant and can withstand high mechanical stress.

[0016] The support rod can be spaced apart from the heating element. This allows shielding of the heating element from the exhaust gas flow by the support rod on the one hand and excessive heating of the support rod by the heating element on the other hand to be minimized. Furthermore, this can also prevent arcing between the support rod and the heating element, for example at very high operating voltages. The distance can be a maximum of 10 mm, 5 mm or 3 mm and a minimum of 0.5 mm or 1 mm. The support rod can have a projection extending in the direction of the heating element, at the end of which the support rod is connected to the heating element. In this way, the support rod can be spaced apart from the heating element and only connected to the heating element in the region of the projection. The projection should therefore be as limited as possible in its dimension in the longitudinal direction of the support rod and, for example,not exceed 1 / 10, 1 / 20 or 1 / 40 of a length of the support bar measured between the two ends.

[0017] The heating element can comprise a heating grid with current-carrying grid elements that have a minimum thickness of no more than 5 mm, 3 mm, or 1 mm, and no less than 0.5 mm, 0.3 mm, or 0.1 mm. Such a heating grid allows the exhaust gas flow to be heated particularly efficiently. At the same time, the heating grid represents a relatively delicate structure, for which a support structure with a carrier rod and sliding element, as disclosed herein, can be particularly advantageous. The heating grid can be designed in the form of a disk, in particular a circular disk, that is arranged concentrically with the housing. In particular, the disk can extend in a radial plane transversely and in particular orthogonally to the axial direction. The heating element can further comprise a support ring arranged between the carrier rod and the heating grid. The support ring can be circular. The support ring can be arranged coaxially and / or parallel to the heating grid.The support ring can be firmly and, in particular, materially connected to the heating grid.

[0018] The heating grid and the support ring can be designed as a single piece and in particular monolithic, i.e., for example, made from a single workpiece. The support rod can be firmly and in particular materially connected to the support ring, e.g. by means of a welded connection and in particular by means of a laser-welded connection. The support ring can provide the required connection between the support rod and the heating element, in particular between the support rod and the heating grid. The support ring can comprise a plurality of legs, each designed as a projection. The legs can act as thermal compensators, minimizing thermally induced mechanical stress on the support ring and components connected to it. The legs can extend in a radial plane of the support ring.

[0019] The electric heating device can comprise two, in particular exactly two, support rods. The support ring can then be arranged between the two support rods and, in particular, connected to them, optionally at a distance corresponding to a diameter of the support ring. In other words, the two support rods can be connected to the support ring at two diametrically opposed contact points. This can provide particularly uniform compensation.

[0020] As an alternative to an embodiment of the heating element with a heating grid, the heating element can be and / or comprise, for example, a heating foam made of current-conducting foam material of a predetermined density. A corresponding heating element is described, for example, in the document DE 10 2021 006 655 A1. The heating foam is heated by applying an electrical voltage and can be flowed through by the exhaust gas stream. Such a heating foam can heat the exhaust gas stream particularly efficiently. At the same time, the heating foam represents a relatively delicate structure, for which a support structure with a carrier rod and sliding element as disclosed here can be particularly advantageous. In a connection region in which the carrier rod is connected to the heating element, the heating element can have a region of increased density. This can increase the stability of the connection, in particular a material-locking connection, between the carrier rod and the heating element.The increased density can be at least 2 or 3 times, and at most 4, 6, or 10 times, the predetermined density of the remaining foam material. The densities depend in particular on the required heating output and stability of the heating device. The connection area can be located centrally in the heating element, particularly in a plane orthogonal to the exhaust gas flow. This will generally be the area of ​​the heating element subject to the greatest mechanical stresses in the heating device.

[0021] The heating foam can be divided by interruptions into sections which, viewed in cross-section, lie next to one another in such a way that a current path is predefined that extends from a current introduction point of the heating element to a current discharge point, for example from one side of the heating element to the other side. The sections can therefore be elongated sections that extend, for example, transversely and in particular orthogonally to the exhaust gas flow. In the case of a heating element designed, for example, as a circular disk, the length of the sections then increases towards the center of the disk, with their mechanical stability simultaneously decreasing. It can be advantageous to use the support rod or rods to support precisely those sections of the heating element that have lower mechanical stability. The heating foam can, for example, be divided into at least five or N ≥ 5 sections, and the number of support rods can correspond to N - 4.In other words, two support bars can be provided for six sections, and four for eight sections. The support bars can be connected to sections that have the lowest mechanical stability, particularly depending on the geometry of the heating element. The number of sections can be a maximum of ten or a maximum of eight, although this can also be considered depending on the heating output and stability of the heating device, as well as the avoidance of hotspot formation. Alternatively, only three or four sections and, accordingly, one or two support bars can be provided.

[0022] The heating device can be designed for a maximum exhaust gas mass flow of at least 600 kg / h and a maximum operating temperature of at least 920 °C.

[0023] The support structure described here, consisting of a support rod and a sliding element, can be used particularly advantageously with a heating element comprising a heating grid or formed as a heating foam, but is of course not limited to this. The heating device can also, in principle, comprise standard electrical heating elements.

[0024] Several embodiments have been disclosed herein. From the following detailed description, which shows and describes three exemplary embodiments of the invention, further embodiments and advantageous combinations of individual features of the present invention will become apparent to those skilled in the art. Accordingly, the drawings and the detailed description are to be considered as exemplary and not restrictive. Recurring features are designated by the same reference numerals in the description of the figures.

[0025] It shows Fig. 1 is a schematic representation of a first embodiment of an electric heating device according to the invention in a sectional view, Fig. 2 a schematic representation of the embodiment of Fig. 1 in a section plane orthogonal to the section view of the Fig. 1, Fig. 3 a schematic detailed view of an exemplary support bar in a sectional view through a plain bearing, Fig. 4 a schematic detailed view of another exemplary support bar in a sectional view through a sliding bearing, Fig. 5 a schematic representation of a second embodiment of an electric heating device according to the invention in a sectional view, Fig. 6 a schematic representation of the embodiment of Fig. 5 in a section plane orthogonal to the section view of the Fig. 5, Fig. 7 a schematic detailed view of a connection between the support rod and the heating element of the heating device of the Fig. 5 and Fig. 8 a schematic representation of a third embodiment of an electric heating device according to the invention in a sectional view.

[0026] In the following, recurring features are described once for all figures. References to specific figures are made only when appropriate.

[0027] The proposed electric heating device 1 for heating an exhaust gas stream comprises a housing 10, an electric heating element 100; 200 accommodated in the housing 10, and at least one support rod 20 connected to the heating element 100; 200 and having two opposite ends arranged on the housing 10. The support rod 20 is movably mounted at at least one of its ends in a sliding bearing 30 to compensate for a thermally induced deformation of the support rod 20, wherein the sliding bearing 30 is fixedly connected to the housing 10.

[0028] In the housing 10, the exhaust gas flow can be guided from an inlet, in particular a housing inlet, to an outlet, in particular a housing outlet. Between the inlet and outlet, an axial direction can be defined in which the exhaust gas flow flows through the housing 10. According to the exemplary illustrations of the Fig. 1, Fig. 5 and Fig. 8, a corresponding exhaust gas flow would flow into the plane of the sheet and according to the illustrations of the Fig. 2, Fig. 3, Fig. 4, Fig. 6 and Fig. 7 move along the sheet planes, in the Fig. 2 and Fig. 6 indicated by dashed arrows.

[0029] In principle, several, i.e. at least two and / or a maximum of six or a maximum of four, in particular identical, support bars 20 can be provided. Thus, in the embodiments according to Fig. 1 and Fig. 5 two each and according to the embodiment of the Fig. 8, four essentially identical support bars 20 are provided, which is why the following description always refers to several support bars 20. The support bars 20 are spaced apart from one another and arranged essentially parallel to one another and at the same distance from the heating element 10.

[0030] In this case, each of the support rods 20 is movably mounted at both ends in a respective sliding bearing 30 to compensate for a thermally induced deformation of the support rod 20, with both sliding bearings 30 being rigidly connected to the housing 10. The sliding bearings 30 are constructed and arranged identically. The following description therefore always refers to multiple sliding bearings 30.

[0031] Each of the support rods 20 extends transversely, in this case orthogonally, to the axial direction of the housing 10 in which the exhaust gas flow flows through the housing 10. Each of the support rods 20 extends between two opposite sides of the housing 10 and through the housing 10. Each of the support rods 20 is arranged parallel to the heating element 100; 200. In the present case, the support rods 20 are arranged in the direction of the exhaust gas flow, ie downstream, in front of the heating element 10. In principle, however, they can also be arranged behind it. The support rods 20 can have a round, in particular a circular (as in Fig. 4), or a rectangular cross-section, in particular with two long and two short sides (as in Fig. 3), wherein the long sides extend along the axial direction of the housing 10. The support rods 20 can be straight, in particular continuously straight, or curved. In the present case, all support rods 20 are curved. The curvature is concave relative to the housing 10, ie, the support rods 20 are curved in a direction orthogonal to the exhaust gas flow toward the center of the housing 10.

[0032] Each of the support rods 20 is arranged at both of its ends by means of a clamp in the respective plain bearing 30, wherein a resulting clamping force exerted by the clamps on the support rods 20 is designed to prevent unwanted displacement and / or shaking of the support rods 20 in the plain bearings 30 during intended use of the electric heating device 1, e.g., when the heating device 1 is installed as part of an exhaust system in a vehicle. In other words, the support rods 20 are non-positively connected to the plain bearings 30. Each of the plain bearings 30 comprises an outer casing 31 that completely surrounds the respective support rod 20. The respective support rod 20 is thus received at its corresponding end in a recess of the corresponding plain bearing 30, which is defined by the outer casing 31, as can be seen particularly from the Fig. 3 and Fig. 4. The recess and support rod 30 are arranged in alignment with one another. In other words, the recess extends in the same direction as the support rod 20 received therein and thereby forms a sliding seat for the respective support rod 30. The outer casing 31 comprises two opposing casing halves 31a, 31b. Each of the plain bearings 30 comprises an electrically and thermally insulating layer 32 arranged between the outer casing 31 and the support rod 30. Thus, in the present case, the support rods 20 are electrically and thermally insulated from the housing 10 at least by means of the plain bearings 30. The insulating layer 32 can be elastic, which makes it easier to adjust, for example, a required clamping force.The insulating layer 32 can comprise or consist of a needle-like polycrystalline fiber mat, a ceramic, in particular aluminum oxide ceramic, material, and / or a glass fiber-reinforced ceramic composite material. According to the example of . Fig. 4, one of the two jacket halves 31a partially overlaps the other jacket half 31b in the circumferential direction of the support rod 30. The insulating layer 32 is arranged directly adjacent to the support rod 20 and the outer jacket 31. If appropriate, however, additional insulating intermediate layers can also be provided, which are, for example, electrically and / or thermally insulating layers.

[0033] Each of the support bars 20 is connected to the heating element 100; 200 at a single contact point, which may also be referred to herein as connection 40. Each of the support bars is firmly and materially connected to the heating element 100; 200. The connection 40 may be a welded connection, and in particular a laser-welded connection, as shown in the Fig. 2, Fig. 6 and Fig. 7. The support rods 20 can be made of metal or comprise a metal. The metal can be or comprise, in particular, a high-alloy stainless steel, such as 1.4301, or a NiCr alloy. These materials are particularly temperature-resistant and can withstand high mechanical stresses.

[0034] Each of the support rods is spaced apart from the heating element 100; 200. The distance d can be at most 10 mm, 5 mm, or 3 mm and at least 0.5 mm or 1 mm. Each of the support rods 20 has a projection 21 extending in the direction of the heating element 100; 200, at the end of which the respective support rod 20 is connected to the heating element 100; 200. The projection 21 is limited in its dimension in the longitudinal direction of the respective support rod 20 and amounts, for example, to no more than 1 / 10, 1 / 20, or 1 / 40 of a length of the respective support rod 20 measured between the two ends.

[0035] According to the embodiment of the Fig. 1, the heating element 100 comprises a heating grid 110 with current-carrying grid elements. Electrodes for applying an electrical voltage required for the heating process to the heating element 100 are not shown here. The grid elements can have a minimum thickness of no more than 5 mm, 3 mm, or 1 mm, and no less than 0.5 mm, 0.3 mm, or 0.1 mm. The heating grid 110 is designed in the form of a circular disk that is arranged concentrically with the housing 10. The heating grid 110 extends in a radial plane orthogonal to the axial direction. A minimum thickness or dimension can be, for example, 1 mm in the axial direction and 0.1 mm in a radial direction. The heating element 100 further comprises a support ring 120 arranged between each of the support bars 20 and the heating grid 110. The support ring 120 is circular and arranged parallel to the heating grid 110.The support ring 120 is firmly and materially connected to the heating grid 110. The heating grid 110 and the support ring 120 can be designed as a single piece and, in particular, as a monolithic structure, i.e., for example, made from a single workpiece. Each of the support rods 20 is firmly and materially connected to the support ring 120, e.g., by means of a welded connection, and in particular, by means of a laser-welded connection. For example, in the present case, the support ring shown in . Fig. 2 is connected to the heating grid 110 via the support ring 120. The support ring 120 comprises a plurality of legs 122, each designed as a projection. The legs 122 extend in a stepped manner in a radial plane of the support ring 120. The electric heating device 1 according to Fig. 1 comprises exactly two support rods 20. The support ring 120 is arranged between the two support rods 20 and connected to them at a distance corresponding to a diameter of the support ring 120. In other words, the two support rods 20 are connected to the support ring 120 at two diametrically opposed contact points or connections 40.

[0036] As an alternative to the embodiment of the heating element 100 with heating grid 110, the heating element 200 may be, for example, a heating foam 210 made of current-conducting foam material of a predetermined density or comprise this, as shown in the Fig. 5 to 8. The heating foam 210 is heated by applying an electrical voltage and can be flowed through by the exhaust gas stream. In the present two examples, the required heating voltage is provided by two opposing electrodes 50. In a connecting region, in which the support rods 20 are connected to the heating element 200, the heating element 200 has a region of increased density 220. The increased density can correspond to at least 2 times or 3 times and at most 4 times, 6 times or 10 times the predetermined density of the remaining foam material. The connecting region or region of increased density 220 is arranged centrally in the heating element 200 in a plane orthogonal to the exhaust gas stream, as shown in the Fig. 5 and Fig. 8. Additional areas of increased foam density may be provided on the outer periphery of the heating element 200, as shown in Fig. 6. However, these primarily serve to improve current conduction, as explained in more detail in the above-mentioned document DE 10 2021006 655 A1. In the present case, the heating foam 210 is divided by interruptions 211 into sections 212 which, viewed in cross-section, are arranged next to one another in such a way that a current path is predefined that extends from a current introduction point or first electrode 50 of the heating element to a current discharge point or second electrode 50, in this case from one side of the heating element 200 to the other side. The sections 212 are elongated sections 212 that extend orthogonally to the exhaust gas flow. Since the heating element 200 is circular in each case, the length of the sections 212 increases towards the center of the disc, with their mechanical stability generally decreasing at the same time. The support bars 20 support precisely those sections of the heating element 20 which have a lower mechanical stability.In order to support the relevant sections 212 as far as possible in areas of lower mechanical stability, the projections 21 of the respective support bars 20 are designed in a step-like manner towards the center of the sections 212, as shown in . Fig. 7. The heating foam can, for example, be divided into at least five or

[0037] N ≥ 5 sections and the number of support bars is N-4. In other words, as in Fig. 5, with six sections 212 two support bars 20 and, as in Fig. 8, four support rods 20 are provided for eight sections 212. The support rods 20 are connected to sections 212 that have the least mechanical stability, in this case, arranged centrally in the housing 10. The number of sections 212 can be a maximum of ten or a maximum of eight. Alternatively, only three or four sections 212 and, accordingly, one or two support rods 20 can be provided.

[0038] The heating device 1 can be designed for a maximum mass flow of the exhaust gas of at least 600 kg / h and a maximum operating temperature of at least 920 °C. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2021 006 655 A1 [0020, 0036]

Claims

[1] Electric heating device (1) for heating an exhaust gas stream, comprising: a housing (10), an electric heating element (100; 200) and at least one support rod (20) connected to the heating element (100; 200) with two opposite ends arranged on the housing (10) are accommodated in the housing (10), wherein the support rod (20) is movably arranged at at least one of its ends in a sliding bearing (30) to compensate for a thermally induced change in shape of the support rod (20), wherein the sliding bearing (30) is fixedly connected to the housing (10). [2] Electric heating device (1) according to claim 1, wherein the support rod (20) is movably arranged at both of its ends in a respective sliding bearing (30) for compensating for a thermally induced change in shape of the support rod (20), wherein the sliding bearings (30) are fixedly connected to the housing (10). [3] Electric heating device (1) according to claim 1 or 2, wherein the support rod (20) extends transversely and in particular orthogonally to an axial direction of the housing (10) in which the exhaust gas flow flows through the housing (10). [4] Electric heating device (1) according to one of the preceding claims, wherein the support rod (20) is electrically and / or thermally insulated from the housing (10), in particular by means of the sliding bearing (30). [5] Electric heating device (1) according to one of the preceding claims, wherein the support rod (20) is arranged in the sliding bearing (30) by means of a clamp, wherein a resulting clamping force exerted on the support rod (20) by the clamp is designed to prevent unwanted displacement and / or shaking of the support rod (20) in the sliding bearing (30) when the electric heating device (1) is used as intended. [6] Electric heating device (1) according to one of the preceding claims, wherein the sliding bearing (30) comprises an outer casing (31) surrounding the support rod (20), in particular completely circumferentially, optionally consisting of two opposing casing halves (31a, 31b), and an electrically and / or thermally insulating insulating layer (32) arranged between the outer casing (31) and the support rod (20), wherein the insulating layer (32) optionally comprises or consists of a needle-like polycrystalline fiber mat, a ceramic, in particular aluminum oxide-ceramic, material and / or a glass fiber-reinforced ceramic composite material. [7] Electric heating device (1) according to one of the preceding claims, wherein the support rod (20) is connected to the heating element (100; 200) at a single contact point and / or is firmly connected, in particular is materially connected, for example by means of a welded connection and in particular by means of a laser-welded welded connection. [8] Electric heating device (1) according to one of the preceding claims, wherein the support rod (20) is spaced from the heating element (100; 200) and the distance (d) is optionally at most 10 mm, 5 mm or 3 mm and at least 0.5 mm or 1 mm. [9] Electric heating device (1) according to one of the preceding claims, wherein the support rod (20) has a projection (21) extending in the direction of the heating element (100; 200), at the end of which the support rod (20) is connected to the heating element (100; 200). [10] Electric heating device (1) according to one of the preceding claims, wherein the heating element (100) comprises a heating grid (110) with current-carrying grid elements which have a minimum thickness of not more than 5 mm, 3 mm or 1 mm and not less than 0.5 mm, 0.3 mm or 0.1 mm, and the heating element (100) further comprises a support ring (120) which is arranged between the support rod (20) and the heating grid (110), wherein the support ring (120) is in particular firmly connected, optionally materially connected, to the heating grid (110) and / or the support rod (20) is firmly connected, optionally materially connected, to the support ring (120), in particular by means of a welded connection, optionally a laser-welded welded connection, and / or the support ring (120) comprises a plurality of legs (122) each designed as a projection. [11] Electric heating device (1) according to the preceding claim, wherein the electric heating device (1) comprises two support bars (20) and the support ring (120) is arranged between the two support bars (20) and in particular is connected to them, optionally at a distance corresponding to a diameter of the support ring (120). [12] Electric heating device (1) according to one of claims 1 to 9, wherein the heating element (200) is a heating foam (210) made of current-carrying foam material of a predetermined density and has a region of increased density (220) in a connecting region in which the support rod (20) is connected to the heating element (100; 200). [13] Electric heating device (1) according to the preceding claim, wherein the heating foam (210) is divided by interruptions (211) into sections (212) which, viewed in a cross-section, lie next to one another in such a way that a current path is predefined which extends from a current introduction point of the heating element (200) to a current discharge point, for example from one side of the heating element (200) to the other side, wherein optionally the heating foam (210) is divided into N ≥ 5 sections (212) and the number of support bars (20) corresponds to N-4. [14] Electric heating device (1) according to one of the preceding claims, wherein the support rod (20) has a round, in particular a circular, or a rectangular cross-section, in particular with two long and two short sides, wherein the long sides extend along an axial direction of the housing (10) in which the exhaust gas flow flows through the housing (10). [15] Electric heating device (1) according to one of the preceding claims, wherein the heating device (1) is designed for a maximum mass flow of the exhaust gas of at least 600 kg / h and a maximum operating temperature of at least 920 °C.

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