ELECTRIC EXHAUST GAS HEATER

Description

[0001] The present invention relates to an exhaust gas heater for an exhaust system of an internal combustion engine, comprising a support arrangement through which exhaust gas can flow essentially in the direction of an exhaust gas heater longitudinal axis and at least one heating conductor carried on the support arrangement.

[0002] Such an exhaust gas heater is generally used to heat exhaust gas flowing through an exhaust system of an internal combustion engine or another gas conducted through an exhaust system in order to transfer the heat transferred to the exhaust gas or gas in a region of the exhaust system downstream of the exhaust gas heater to other system regions, for example an exhaust gas treatment unit such as a catalytic converter or particulate filter, in order to bring such system regions to operating temperature as quickly as possible, particularly in a start-up phase of the combustion operation or before the start of the combustion operation of an internal combustion engine.

[0003] German patent application DE 10 2020 123 376 discloses an exhaust gas heater in which a heating conductor is formed with a plurality of heating conductor meander fields. In each heating conductor meander field, radially staggered meander sections extend essentially in the circumferential direction. The heating conductor is provided as a single piece of material by cutting it out of a flat metal material, which allows for a great deal of flexibility in the design of the individual heating conductor meander fields or the meander sections in the individual heating conductor meander fields.

[0004] An exhaust gas heater according to the preamble of claim 1 is known from DE 20 2021 100 999 U1. This exhaust gas heater comprises a heating conductor arranged in a tubular housing, which is formed by bending a heating strip with a heating conductor meander field. The heating conductor meander field has a plurality of mutually parallel meander sections, which are alternately connected in the meander section end regions by meander section connecting sections.

[0005] It is the object of the present invention to provide an exhaust gas heater for an exhaust system of an internal combustion engine with which increased heating efficiency can be achieved.

[0006] According to the invention, this object is achieved by an exhaust gas heater for an exhaust system of an internal combustion engine according to claim 1, comprising a carrier arrangement through which exhaust gas can flow essentially in the direction of an exhaust gas heater longitudinal axis and at least one heating conductor carried on the carrier arrangement

[0007] The at least one heating conductor is constructed with flat material bent to provide a meandering heating conductor path at least in some areas, with opposing heating conductor flat sides and opposing heating conductor broad sides.

[0008] In the exhaust gas heater design according to the invention, the heating conductor is not provided by separating, for example, punching or cutting out, a flat metal material with a defined shape, but rather by bending a flat material, for example a strip-like material, into the shape intended for the heating conductor. This makes it possible to provide the heating conductor with a structure that is very thin, particularly transverse to the exhaust gas flow direction, but comparatively extensive in the exhaust gas flow direction. This, on the one hand, reduces the flow resistance in the exhaust gas heater and, on the other hand, allows a comparatively large surface area usable for heat transfer to be provided.

[0009] This can be achieved in particular if the at least one heating conductor is arranged with its heating conductor broad sides extending substantially in the direction of the exhaust gas heater longitudinal axis and is arranged with its heating conductor flat sides extending substantially orthogonally to the exhaust gas heater longitudinal axis.

[0010] In the present invention, the at least one heating conductor comprises at least one heating conductor meander array with a plurality of meander sections elongated in the direction of a meander section longitudinal direction and substantially parallel to one another, wherein directly adjacent meander sections transverse to the meander section longitudinal direction are connected to one another in one of their meander section end regions by a meander section connecting section. Such an arrangement achieves a very dense packing of the individual meander sections and thus a large surface area for heat transfer relative to the total cross-section through which exhaust gas can flow.

[0011] A further increase in the surface area available for heat transfer is achieved in that at least one, preferably substantially every meander section is formed between its meander section end regions at least partially in a wave-like manner with a plurality of wave crests following one another in the meander section longitudinal direction.

[0012] In particular, when the heating conductor is provided by flat material bent into the desired shape, it is advantageous for the simplest possible production if the at least one heating conductor comprises at least two heating conductor meander fields, wherein a first heating conductor meander field of the at least two heating conductor meander fields provides a first connection area for connecting the at least one heating conductor to a voltage source and a second heating conductor meander field of the at least two heating conductor meander fields provides a second connection area for connecting the at least one heating conductor to the voltage source.

[0013] At least one heating conductor meander field can be provided by a single piece of heating conductor material. This means that such a heating conductor meander field can be provided without having to mechanically or electrically connect different or separately formed pieces of material to one another. It is particularly advantageous if all heating conductor meander fields are provided by a single piece of heating conductor material, so that no joining processes for joining separate pieces of material are required to provide the entire heating conductor.

[0014] Particularly in the case of larger dimensions of an exhaust gas heater or a comparatively complex course of the heating conductor, it can be advantageous for simple production if at least two heating conductor meander fields are provided by separate heating conductor material pieces.

[0015] The structure can be simplified by using identical parts if at least two, preferably all, heating conductor meander fields provided by separate heating conductor material pieces are essentially of the same shape to one another.

[0016] In order to achieve the most uniform possible flow through the exhaust gas heater in its entire cross-section during heating operation, it is proposed that at least two heating conductor meander fields provided by separate heating conductor material pieces are designed to be substantially mirror-symmetrical to one another with respect to a plane of symmetry containing the heating conductor longitudinal axis.

[0017] If the heating conductor is formed with two heating conductor meander fields provided by separate pieces of heating conductor material, the two heating conductor meander fields can be arranged essentially mirror-symmetrically to one another with respect to a plane of symmetry containing the heating conductor's longitudinal axis. For example, if the heating conductor is formed with four heating conductor meander fields provided by separate pieces of heating conductor material, the four heating conductor meander fields can be arranged in pairs essentially mirror-symmetrically to one another with respect to two mutually orthogonal planes of symmetry containing the heating conductor's longitudinal axis.

[0018] According to a further aspect of the present invention, which independently, but in particular also in conjunction with the previously discussed design aspects, contributes to a particularly advantageous design of an exhaust gas heater, the support arrangement can comprise a support housing with a housing base arranged on a first axial side of the at least one heating conductor and extending substantially transversely to the exhaust gas heater longitudinal axis, wherein a plurality of exhaust gas flow openings are provided in the housing base, and wherein the at least one heating conductor is carried by a plurality of support elements on the housing base.

[0019] In order to ensure, on the one hand, a stable mounting of the heating conductor on the support arrangement and, on the other hand, to keep the flow resistance introduced thereby as low as possible, it is proposed that at least one, preferably each support element comprises a support pin fixed to the housing base and a support sleeve carried on the support pin with the intermediate storage of electrically insulating material, preferably magnesium oxide material, and fixed to the at least one heating conductor, and / or that at least one, preferably each support element is arranged with a support element longitudinal axis substantially parallel to the exhaust gas heater longitudinal axis.

[0020] For a simple-to-implement, yet mechanically stable, and in particular exhaust-gas- and temperature-resistant design, the support housing as well as the support pin and the support sleeve of the at least one, preferably each, support element can be constructed of metal material. The support pin of the at least one, preferably each, support element can be connected to the housing base by a material bond, preferably by welding or soldering. Furthermore, the support sleeve of the at least one, preferably each, support element can be connected to the at least one heating conductor by a material bond, preferably by welding or soldering.

[0021] In particular, when the heating conductor is constructed with several pieces of material provided separately from one another, it is advantageous for a stable construction and to achieve an electrically conductive connection between all the pieces of material if at least two heating conductor meander fields provided as separate heating conductor material pieces are electrically conductively connected to one another by means of at least one carrier element carrying them on the carrier housing.

[0022] For example, in order to be able to connect the support housing to a tubular or housing-like exhaust gas duct component of an exhaust system, it can have a peripheral wall that adjoins the housing base radially on the outside.

[0023] The support housing can be pot-shaped with the housing base and the peripheral wall. In order to achieve a defined flow pattern on the one hand, and to keep the flow resistance as low as possible while still being able to provide a large heat transfer surface, it is further proposed that the at least one heating conductor be substantially not covered by the support arrangement on a second axial side and / or that the at least one heating conductor protrude axially beyond the peripheral wall on the second axial side.

[0024] The invention further relates to an exhaust system for an internal combustion engine, comprising at least one exhaust gas treatment unit, preferably a catalyst and / or particle filter, and at least one exhaust gas heater constructed according to the invention in a main exhaust gas flow direction upstream of the at least one exhaust gas treatment unit.

[0025] The present invention is described in detail below with reference to the accompanying figures. It shows: Fig. 1 is a perspective view of an exhaust gas heater viewed from a first axial side oriented, for example, upstream with respect to a main exhaust gas flow direction; Fig. 2 is a perspective view of the Fig. 1 illustrated exhaust gas heater, viewed on a second axial side oriented, for example, downstream of the main exhaust gas flow direction; Fig. 3 an axial view of the exhaust gas heater of Fig. 1 and 2 , viewed on the second axial side; Fig. 4 a detailed view of the exhaust gas heater of the Fig. 1 and 2 ; Fig. 5 another detailed view of the exhaust gas heater of the Fig. 1 and 2 ; Fig. 6one of the Fig. 2corresponding view of an exhaust gas heater of an alternative embodiment; Fig. 7 a heating conductor of the exhaust gas heater of the Fig. 6 ; Fig. 8one of the Fig. 7 corresponding view of another alternatively designed heating conductor with four heating conductor meander fields provided as separate pieces of material; Fig. 9 one of the Fig. 1 corresponding view of an alternative design of an exhaust gas heater; Fig. 10 a side view of the exhaust gas heater of the Fig. 9 ; Fig. 11 a schematic representation of an exhaust system for an internal combustion engine containing an exhaust gas heater and an exhaust gas treatment unit.

[0026] Before referring to the Fig. 1 to 10 various embodiments of an exhaust gas heater that can be used in an exhaust system of an internal combustion engine are described, with reference to the Fig. 11explained how such an exhaust gas heater is integrated into an exhaust system of an internal combustion engine, for example in a vehicle.

[0027] The Fig. 11shows a schematic representation of such an exhaust system 10 with a tubular or housing-like exhaust gas guide component 12, which may be composed of several parts. In an upstream region of this exhaust gas guide component 12, an exhaust gas heater, generally designated 14, is arranged in such a way that exhaust gas flowing in a main exhaust gas flow direction A in the exhaust gas guide component 12 towards the exhaust gas heater 14 flows against it on a first axial side 16. The exhaust gas flows through the exhaust gas heater 14 and, as it flows through the exhaust gas heater 14, absorbs heat from two heating conductors 18, 20 arranged one after the other in the direction of an exhaust gas heater longitudinal axis L. After flowing through the exhaust gas heater 14 or the heating conductors 18, 20 arranged in the main exhaust gas flow direction A orThe heated exhaust gas flow leaves the exhaust heater 14 at a second axial side 22 via heating conductors 18, 20 arranged successively in the direction of the exhaust heater's longitudinal axis L and flows toward an exhaust gas treatment unit 24 arranged downstream of the exhaust heater 14. This unit can be designed, for example, as a catalyst and comprise a catalyst block 28 supported, for example, by means of a fibrous bearing material 26 in the exhaust gas guide component 12.

[0028] The exhaust gas heated in the exhaust gas heater 14 or another gas introduced into the exhaust gas guide component 12 and flowing through the exhaust gas heater 14 transfers heat to the exhaust gas treatment unit 24, so that the latter is quickly brought to the temperature required to carry out the catalytic reaction, in particular before or during commissioning of an internal combustion engine, and the period during which exhaust gas is emitted essentially without a cleaning effect can be significantly shortened.

[0029] A first embodiment of such an exhaust gas heater 14 is described below with reference to the Fig. 1 to 5 explained in detail.

[0030] The exhaust gas heater 14 comprises a support arrangement, generally designated 30, on which, in the illustrated embodiment, the two heating conductors 18, 20 arranged one after the other in the direction of the exhaust gas heater's longitudinal axis L are supported. The support arrangement 30 comprises a support housing 32, provided, for example, as a formed sheet metal part, with a housing base 34 arranged essentially transversely, i.e. essentially orthogonally, to the exhaust gas heater's longitudinal axis L and a peripheral wall 36 adjoining the housing base 34 radially on the outside. The support housing 32 thus has a substantially pot-like structure and, with its housing base 34, covers the two heating conductors 18, 20 essentially only on the first axial side 16. On the second axial side 22, the support housing 32 is fundamentally open and preferably does not cover the two heating conductors 18, 20 in any of their radial regions.

[0031] To allow the exhaust gas to flow around the heating conductors 18, 20, a plurality of substantially uniformly distributed exhaust gas flow openings 38 are formed in the housing base 34. If the exhaust gas heater 14, as is also the case in Fig. 11is indicated, is positioned in the exhaust system 10 or the exhaust gas guide component 12 thereof in such a way that the housing base 34 or the first axial side 16 is oriented upstream and thus the exhaust gas flows in the main exhaust gas flow direction A towards the housing base 34 of the support housing 32, the exhaust gas enters the interior of the support housing 32 in the region of the exhaust gas flow openings 38, in which the two heating conductors 18, 20 are positioned. The exhaust gas flows around the heating conductors 18, 20 essentially in a direction corresponding to the main exhaust gas flow direction A or the exhaust gas heater longitudinal axis L and, after thermal interaction with the heating conductors 18, 20, leaves the support housing 32 at the basically open second axial side 22.

[0032] It should be noted that, in principle, the exhaust gas heater 14 could also be integrated into the exhaust system 10 in a different orientation, so that the exhaust gas flowing towards it in the main exhaust gas flow direction A enters the support housing 32 on the second axial side 22 and, after flowing around the heating conductors 18, 20 in the region of the exhaust gas flow openings 38, exits the support housing 32 on the first axial side 16.

[0033] The basic structure of the two heating conductors 18, 20 is explained below with reference to the heating conductor 20 positioned closer to the second axial side 22. The two heating conductors 18, 20 are basically the same but not completely identical, so that when viewed in the direction of the exhaust gas heater's longitudinal axis, they are not completely congruent and therefore provide improved thermal interaction with the exhaust gas or exhaust gas flowing around them.

[0034] Gas can be reached. However, the following statements also apply in principle to the structure of the heating conductor 16 positioned closer to the first axial side 16.

[0035] The heating conductor 18 is in the Fig. 1 to 5The illustrated embodiment of an exhaust gas heater 14 is made from a single piece of heating conductor material 59. In particular, the heating conductor 18 is constructed from an electrically conductive, generally metal-constructed, strip-like flat material that is bent to obtain the desired shape of the heating conductor 20. The heating conductor 20 thus has opposing broad sides 40, 42, which extend substantially in the direction of the exhaust gas heater's longitudinal axis L or are oriented parallel thereto. The heating conductor 20 further has heating conductor flat sides 44, 46, which are oriented substantially orthogonally to the heating conductor broad sides 40, 42 and also to the exhaust gas heater's longitudinal axis L. By designing the heating conductor 20 or each heating conductor 18, 20 with flat material, it is thus possible, even when using very thin flat material, i.e. a flat material in which the flat sides 44, 46 have a comparatively small expansion orThickness, to provide a large heat transfer surface by appropriately dimensioning the broad sides 40, 42. The extension of the heating conductor broad sides 40, 42 in the direction of the exhaust gas heater's longitudinal axis can, for example, be more than five times, preferably more than ten times, the extension of the heating conductor flat sides 44, 46 orthogonal to the exhaust gas heater's longitudinal axis L. The or each heating conductor 18, 20 is thus significantly wider than it is thick.

[0036] The heating conductor 20 is bent in such a shape that it has two in the view of the Fig. 3to the left and right of a symmetry plane E 1 containing the exhaust gas heater's longitudinal axis L or oriented parallel thereto, respectively, heating conductor meander fields F 1 , F 2 . In each of the heating conductor meander fields F 1 , F 2 , the heating conductor 20 is formed with meander sections 48 that are elongated in a meander section longitudinal direction M and arranged essentially parallel to one another. Meander sections 48 that are immediately adjacent to one another transversely to the meander section longitudinal direction M are connected to one another in one of their meander section end regions 50, 52 located in the meander section longitudinal direction M by means of a respective meander section connecting section 54, 56. Thus, in each of the heating conductor meander fields F 1 , F 2 , there is a meander-like course of meander sections 48 which are essentially elongated in the meander section longitudinal direction M and follow one another transversely to the meander section longitudinal direction M.

[0037] In Fig. 5 It can be clearly seen that the meander sections 48, which lie next to one another transversely to the respective meander section longitudinal direction M, have a fundamentally wave-like course between their respective meander section end regions 50, 52, with successive wave crests 60, 61 spaced apart from one another transversely to the meander section longitudinal direction M. The wave crests 60, 61 thus form an alternating sequence of wave crests and wave troughs in the meander sections 48 in the meander section longitudinal direction M.

[0038] By superimposing this wave-like structure of the individual meander sections 48 on the one hand and the fundamentally meander-like structure of the heating conductor 20 in the heating conductor meander fields F 1 , F 2 , a comparatively large overall length of the heating conductor 20 and thus a large overall surface available for heat transfer is achieved with a compact design. Nevertheless, the overall structure of the heating conductor 18 can be easily adapted to the cross-sectional geometry of the carrier housing 32 that accommodates it, for example, the Fig. 3 clearly recognizable, essentially circular cross-sectional geometry, and essentially an approximately equal surface area usable for heat transfer is provided in each cross-sectional area.

[0039] In the Fig. 1 to 5In the embodiment shown, the heating conductor 20 and also the heating conductor 18 are constructed from a single strip-like heating conductor material piece 59. This means that no processes are required to join individual pieces of material together to produce the heating conductor 20 or 18. By bending into the desired shape with the two heating conductor meander fields F 1 , F 2 , a shape that is essentially mirror-symmetrical to the plane of symmetry E 1 is achieved, in which Fig. 3In the area visible below, the two heating conductor meander fields F 1 , F 2 are connected to one another in the area of ​​their respective lowest meander sections 48 via a meander field connecting section 58, which connects to the meander section end regions 50 of these two meander sections 48 of the two heating conductor meander fields F 1 , F 2 that are close to the peripheral wall 36 and also forms a component of the heating conductor material piece 59 used to construct the heating conductor 20.

[0040] In the Fig. 3In the area visible above, the heating conductor 20 provides a first connection area 63 in the area of ​​the first heating conductor meander field F 1, in which the heating conductor 20 is or can be connected to a connection element 62 that passes through the peripheral wall 36 and possibly also a wall of the exhaust gas guide component 12 in an electrically insulated manner, and via this connection element to a voltage source. Likewise, the heating conductor 20 provides a second connection area 64 in its second heating conductor meander field F 2, in which it can be connected to a voltage source via a connection element 66.In the example shown, in which two heating conductors 18, 20 are arranged one after the other in the direction of the exhaust gas heater longitudinal axis L, these are preferably electrically connected in parallel to one another and are electrically conductively connected to the connection element 62 with a respective first connection region 63 and electrically conductively connected to the connection element 66 with a respective second connection region 64.

[0041] For stable mounting of the heating conductors 18, 20 on the support housing 32, a plurality of pin-like or bolt-like support elements 68 are provided. Fig. 3 It can be seen that two rows of such support elements 68 are provided in association with each of the two heating conductor meander fields F 1 , F 2 , wherein in each of these rows, directly successive support elements 68 are arranged offset from one another transversely to a respective row longitudinal direction.

[0042] Each support element 68 comprises a support pin 70 which is inserted into an associated opening 72 in the housing base 34 and is fixed to the housing base 34, for example by welding or soldering, i.e. basically by material bonding, in such a way that the support pin 70 and thus the entire support element 68 with a support element longitudinal axis S extends essentially in the direction of the exhaust gas heater longitudinal axis L from the housing base 34.

[0043] Each carrier pin 70 is surrounded by a substantially cylindrical carrier sleeve 74. To achieve electrical insulation between a respective carrier pin 70 and the surrounding carrier sleeve 74, an electrically insulating material 76, for example, a ceramic material such as magnesium oxide or the like, is arranged between them. This can be achieved, for example, by coating the outer peripheral region of the carrier pin 70, which receives the carrier sleeve 74, with such electrically insulating material before a respective carrier sleeve 74 is pushed or pressed onto an associated carrier pin 70.

[0044] In order to ensure an electrical short circuit between the carrier sleeve 74 and the housing base 34 in each of the carrier elements 68, the carrier pins 70 with their length sections to be inserted into the openings 72 protrude beyond the respectively associated carrier sleeves 74, so that when the carrier pins 70 are inserted into the openings 72, the carrier sleeves 74 are positioned at a distance from the housing base 34.

[0045] The heating conductors 18, 20 are connected to the support sleeves 74 of the support elements 68 in the region of their meander sections 48, which are generally designed with a wave-like structure. For example, it can be provided that where a meander section 48 is connected to a support sleeve 74, a respective wave crest 60 extends somewhat further in the meander section longitudinal direction M than other wave crests, so that in this region a contour of the respective meander section 48 is achieved that is adapted to the outer circumferential contour of a respective support sleeve 74. In the length region surrounding or adjacent to a respective support sleeve 74, a respective meander section 48 can be connected to the support sleeve 74 by material bonding, for example by welding or soldering.

[0046] Since the support sleeves 74, as well as the support pins 70, are preferably constructed from metal material, there is an electrically conductive connection between the heating conductors 18, 20 where the two heating conductors 18, 20 are in contact with the same support sleeve 74. In order to nevertheless achieve a uniform current flow and thus uniform heating, it is therefore advantageous to design the heating conductors 18, 20 of the same length or with the same electrical resistance between all the support sleeves 74 that follow one another in the direction of current flow and that generate such a short circuit.

[0047] One can see in the Fig. 3 to 5It is clear that, for example, the connection of the immediately adjacent meander sections 48 in a respective heating conductor meander field F 1 , F 2 can be such that only every second meander section 48 is connected to a carrier element 68 or a carrier sleeve 74, while meander sections 48 lying in between, where the rows of carrier elements 68 are formed in each of the two heating conductor meander fields F 1 , F 2 , have an interruption in the wave-like structure with a longitudinal section 77 extending essentially rectilinearly in the meander section longitudinal direction M, in order to provide sufficient installation space for positioning a respective carrier element 68 without the risk of an electrical short circuit.

[0048] To be able to Fig. 1 to 5In order to fundamentally avoid a short circuit between the two heating conductors 18, 20 where this should not be the case, the two heating conductors 18, 20 can be arranged at a slight distance from one another in the direction of the exhaust gas heater's longitudinal axis L. To achieve this, for example, the support sleeves 14 can have a radially outwardly projecting spacer region to create such an intermediate space, against which the two heating conductors 18, 20 can axially abut where they touch a respective spacer sleeve 74.

[0049] An alternative design of an exhaust gas heater 14 is shown in the Figs. 6 and 7 shown. In this exhaust gas heater 14, basically only one heating conductor 18 is used, which can be constructed longer in the direction of the exhaust gas heater longitudinal axis L, for example, than each of the heating conductors 18, 20 of the previously described embodiment. Figs. 6 and 7The heating conductor 18, which is used and is similarly designed with two heating conductor meander fields F 1 , F 2 which are essentially mirror-symmetrical to the symmetry plane E 1, is constructed with two separate heating conductor material pieces 78, 80. As shown in Fig. 7 As can be seen, the basic course of the heating conductor 18 in the two heating conductor meander fields F 1 , F 2 is designed the same as in the previously described embodiments. This means that here too, the meander sections 48 are elongated in a respective meander section longitudinal direction M and are formed with a wave-like structure. In their meander section end regions 50, 52, immediately adjacent meander sections 48 are connected to one another by the meander section connecting sections 54, 56. Fig. 7It can be clearly seen that the two heating conductor material pieces 78, 80 providing a respective heating conductor meander field F 1 , F 2 are fundamentally identical in shape, so that the previously mentioned essentially mirror-symmetrical structure with respect to the plane of symmetry E 1 is again achieved. This means that the same parts can be used for the two heating conductor meander fields F 1 , F 2 , which makes the structure simpler and more cost-effective.

[0050] In each of the heating conductor meander fields F 1 , F 2 , a connection region 63 or 64 is provided. In the end regions of the respective heating conductor material pieces 78, 70 or meander fields F 1 , F 2 that are remote from the connection regions 63 or 64, a respective last and, for example, substantially non-wave-shaped meander section 48 can provide a connection region 82, 83. These connection regions 82, 83 can be connected to the meander field connection section 58, which is now provided as a separate component, in order to electrically connect the two fundamentally separately constructed heating conductor meander fields F 1 , F 2 to one another. Fig. 6that a carrier element 68 can also be assigned to this meander field connecting section 58, so that in or near the connecting regions 82, 83 the two heating conductor meander fields F 1 , F 2 are carried on the carrier housing 32 via a component that electrically connects them, namely the meander field connecting section 58 and a carrier element 68 connected to it in the manner described above.

[0051] A further design of an exhaust gas heater or a heating conductor 18 for this is shown in Fig. 8 It should be noted that this type of design also applies to the Figs. 6 and 7 illustrated embodiment, the carrier housing 32 basically has the Fig. 1 to 5 may have a structure already described

[0052] The Fig. 8The heating conductor 18 shown is constructed with a total of four heating conductor meander fields F 1 , F 2 , F 3 , F 4 . Each of these heating conductor meander fields F 1 , F 2 , F 3 , F 4 is constructed with a separate heating conductor material piece 78, 80, 84, 86. The material pieces 78, 80 used to construct the first heating conductor meander field F 1 and the second heating conductor meander field F 2 provide the connection areas 63, 64. The material pieces 84, 86 used to construct the third heating conductor meander field F 3 and the fourth heating conductor meander field F 4 provide the connection areas 82, 83, via which the third heating conductor meander field F 3 and the fourth heating conductor meander field F 4 can be connected using the method shown, for example, in Fig. 6 recognizable meander field connecting section 58. This in turn can be carried on the support housing 32 via a support element 68.

[0053] Where the second heating conductor meander field F 2 adjoins the third heating conductor meander field F 3 or the first heating conductor meander field F 1 adjoins the fourth heating conductor meander field F 4, these can be mechanically and electrically connected to one another via a carrier element 68 shown in principle and can be carried on the housing base 34 of the carrier housing 32.

[0054] Also in the Fig. 8 The heating conductors 18 shown can be used to construct the four heating conductor meander fields F 1 , F 2 , F 3 , F 4 using identically shaped or bent heating conductor material pieces 78, 80, 84, 86. This results in adjacent heating conductor meander fields being formed or arranged in pairs with mirror symmetry relative to each other with respect to two planes of symmetry E 1 and E 2 .

[0055] By using a total of four heating conductor material pieces 78, 80, 84, 86 or four heating conductor meander fields F 1 , F 2 , F 3 , F 4 constructed with them, the length of each individual heating conductor material piece 78, 80, 84, 86 is significantly shorter, so that the manufacturing or bending process can be carried out much more easily.

[0056] The Fig. 9 and 10 show an alternative design of the support housing 32 used in an exhaust gas heater 14. It can be seen in Fig. 9 that exhaust gas flow openings 38 of different shapes are provided in the housing base 34. Some of the exhaust gas flow openings 38 are designed with a circular cross-section, while another part is designed like an elongated hole and is elongated, for example, in a direction in which the respective meander sections 48 are also elongated in their respective meander section longitudinal direction M.

[0057] By shaping or varying the shape of the exhaust gas flow openings 38, it becomes possible to direct the exhaust gas in a defined manner into various areas of the interior of the support housing 32, thus achieving a defined flow onto or around the heating conductor(s). It can also be seen that where the openings 72 for receiving the support pins 70 are provided in the housing base 34, axial protrusions 88 can be provided on the housing base 34 in order to achieve increased stability in this area.

[0058] In Fig. 10It can be seen that the housing base 34 of the support housing 32, although it is generally arranged approximately orthogonally or transversely to the exhaust gas heater's longitudinal axis L, can be curved outward, i.e., essentially convexly. This also increases the stability of the structure on the one hand, and on the other hand, ensures a defined flow guidance of the exhaust gas flowing in the main exhaust gas flow direction A toward the exhaust gas heater 14.

[0059] Further on, Fig. 10 It can be seen that the heating conductor(s) 18, 20 and thus also the support elements 68 supporting them can be dimensioned such that they protrude beyond the peripheral wall 36 of the support housing 32 on the second axial side 22. Since the support housing 32 is fundamentally open on this second axial side, there is no conflict with the support housing 32, and the surface area of ​​the heating conductor(s) 18, 20 available for heat transfer can be further increased.

[0060] It should be noted that, of course, the above-mentioned provisions with reference to the Fig. 10 described structure of the support housing 32 or the heating conductors 18, 20 accommodated therein, regardless of the Fig. 9 or in Fig. 1 shown shape or arrangement of the exhaust gas passage openings 38 can be provided and also regardless of whether a heating conductor which is somewhat more extended in the axial direction or two or more heating conductors arranged one after the other in the axial direction are provided in the support housing 32.

Claims

1. An exhaust gas heater for an exhaust gas system of an internal combustion engine, comprising a carrier arrangement (30) through which exhaust gas can flow substantially in the direction of an exhaust gas heater longitudinal axis (L) and at least one heating conductor (18, 20) supported on the carrier arrangement (30), wherein the at least one heating conductor (18, 20) is constructed with bent flat material, for the provision of a heating conductor profile which is meandering at least in regions, with heating conductor flat sides (44, 46) opposite one another and heating conductor broad sides (40, 42) opposite one another, wherein the at least one heating conductor (18, 20) comprises at least one heating conductor meandering field (F1, F2, F3, F4) with a multiplicity of meandering portions (48) which are longitudinally extended in the direction of a meandering portion longitudinal direction (M) and are substantially parallel to one another, wherein directly adjacent meandering portions (48) in in each case one of their meandering portion end regions (50, 52) are connected to one another by a meandering portion connecting portion (54, 56) transversely to the meandering portion longitudinal direction (M), characterized in that at least one meandering portion (48) is formed between its meandering portion end regions (50, 52) at least in regions in an undulating manner with a multiplicity of consecutive wave crests (60, 61) in the meandering portion longitudinal direction (M).

2. The exhaust gas heater as claimed in claim 1, characterized in that the at least one heating conductor (18, 20) with its heating conductor broad sides (40, 42) is arranged extending substantially in the direction of the exhaust gas heater longitudinal axis (L) and with its heating conductor flat sides (44, 46) is arranged extending substantially orthogonally to the exhaust gas heater longitudinal axis (L).

3. The exhaust gas heater as claimed in claims 1 or 2, characterized in that substantially each meandering portion (48) is formed between its meandering portion end regions (50, 52) at least in regions in an undulating manner with a multiplicity of consecutive wave crests (60, 61) in the meandering portion longitudinal direction (M).

4. The exhaust gas heater as claimed in one of claims 1-3, characterized in that the at least one heating conductor (18, 20) comprises at least two heating conductor meandering fields (F1, F2, F3, F4), wherein a first heating conductor meandering field (F1) of the at least two heating conductor meandering fields (F1, F2, F3, F4) provides a first connector region (60) for connecting the at least one heating conductor (18, 20) to a voltage source and a second heating conductor meandering field (F2) of the at least two heating conductor meandering fields (F1, F2, F3, F4) provides a second connector region (60) for connecting the at least one heating conductor (18, 20) to the voltage source.

5. The exhaust gas heater as claimed in any one of claims 1-4, characterized in that at least one heating conductor meandering field (F1, F2, F3, F4) is provided by a single heating conductor material piece (59, 78, 80, 84, 86).

6. The exhaust gas heater as claimed in claim 5, characterized in that all the heating conductor meandering fields (F1, F2) are provided by a single heating conductor material piece (59).

7. The exhaust gas heater as claimed in any one of claims 1-5, characterized in that at least two heating conductor meandering fields (F1, F2, F3, F4) are provided by separate heating conductor material pieces (78, 80, 84, 86).

8. The exhaust gas heater as claimed in claim 7, characterized in that at least two, preferably all the heating conductor meandering fields (F1, F2, F3, F4) provided by separate heating conductor material pieces (78, 80, 84, 86) are formed to have substantially the same shape as one another.

9. The exhaust gas heater as claimed in any one of claims 1-8, characterized in that at least two heating conductor meandering fields (F1, F2, F3, F4) provided by separate heating conductor material pieces (78, 80, 84, 86) are arranged substantially in mirror symmetry to one another in relation to a plane of symmetry (E1, E2) which contains the heating conductor longitudinal axis (L), preferably wherein the heating conductor (18) is formed with two heating conductor meandering fields (F1, F2) provided by separate heating conductor material pieces (78, 80) and the two heating conductor meandering fields (F1, F2) are arranged substantially in mirror symmetry to one another in relation to a plane of symmetry (E1) containing the heating conductor longitudinal axis (L) or the heating conductor (18) is formed with four heating conductor meandering fields (F1, F2, F3, F4) provided by separate heating conductor material pieces (78, 80, 84, 86) and the four heating conductor meandering fields (F1, F2, F3, F4) are arranged in each case in pairs substantially in mirror symmetry to one another in relation to two planes of symmetry (E1, E2) which contain the heating conductor longitudinal axis (L) and are orthogonal to one another.

10. The exhaust gas heater as claimed in any one of claims 1-9, characterized in that the carrier arrangement (30) comprises a carrier housing (32) with a housing base (34) which is arranged on a first axial side (16) of the at least one heating conductor (18, 20) and extends substantially transversely to the exhaust gas heater longitudinal axis (L), wherein a multiplicity of exhaust gas throughflow openings (38) is provided in the housing base (34), and wherein the at least one heating conductor (18, 20) is supported by a multiplicity of carrier elements (68) on the housing base (34).

11. The exhaust gas heater as claimed in claim 10, characterized in that at least one, preferably each carrier element (68) comprises a carrier pin (70) fixed on the housing base (34) as well as a carrier sleeve (74) supported on the carrier pin (70), with the interposition of electrically insulating material (76), preferably magnesium oxide material, and fixed on the at least one heating conductor (18, 20).

12. The exhaust gas heater as claimed in claim 11, characterized in that the carrier pin (70) of the at least one, preferably each carrier element (68) is connected to the housing base (34) by material connection, preferably welding or soldering, and that the carrier sleeve (74) of the at least one, preferably each carrier element (68) is connected to the at least one heating conductor (18, 20) by material connection, preferably welding or soldering.

13. The exhaust gas heater as claimed in claim 7 and any one of claims 10-12, characterized in that at least two heating conductor meandering fields (F1, F2, F3, F4) provided as separate heating conductor material pieces (78, 80, 84, 86) are connected to one another in an electrically conducting manner by means of at least one carrier element (68) which supports these on the carrier housing (32).

14. The exhaust gas heater as claimed in any one of claims 10-13, characterized in that the carrier housing (32) has a circumferential wall (36) which adjoins the housing base (34) radially on the outside.

15. The exhaust gas heater as claimed in claim 14, characterized in that the carrier housing (32) is formed in a pot-shaped manner with the housing base (34) and the circumferential wall (36), and the at least one heating conductor (18, 20) on a second axial side a (22) is substantially not covered by the carrier arrangement (30) or / and the at least one heating conductor (18, 20) on the second axial side (22) projects axially over the circumferential wall (36).

16. An exhaust gas system for an internal combustion engine, comprising at least one exhaust gas treatment unit (24), preferably catalytic converter or / and particle filter, and at least one exhaust gas heater (14) as claimed in any one of the preceding claims in an exhaust gas main flow direction (A) upstream in relation to the at least one exhaust gas treatment unit (24).