阅读说明：本技术 排气加热器 (Exhaust heater ) 是由 E·库尔佩约维克 V·B·索利普拉姆 F·乌伊萨尔 于 2020-11-20 设计创作，主要内容包括：本发明涉及一种用于内燃机的排气设备的排气加热器,所述排气加热器包括：支架(22),所述支架具有关于加热器纵轴线(A)在径向外部设置的外周区域(24)和中央区域(26)以及在支架(22)上支承的热导体(42),其中,热导体(42)包括在支架(22)的第一轴向侧(34)上设置的螺旋状缠绕的加热区段(44),其特征在于,中央区域(26)关于外周区域(24)朝支架(22)的第一轴向侧(34)的方向轴向错开地这样设置,使得加热区段(44)的处于支架(22)的外周区域(24)的区域中的径向外部的端部区段(46)和加热区段(44)的处于支架(22)的中央区域(26)的区域中的径向内部的端部区段(48)相对于彼此轴向错开地设置。(The present invention relates to an exhaust gas heater for an exhaust apparatus of an internal combustion engine, the exhaust gas heater comprising: a support (22) having a peripheral region (24) and a central region (26) which are arranged radially outside with respect to a heater longitudinal axis (A), and having a heat conductor (42) which is mounted on the support (22), wherein the heat conductor (42) comprises a helically wound heating section (44) which is arranged on a first axial side (34) of the support (22), characterized in that the central region (26) is arranged axially offset with respect to the peripheral region (24) in the direction of the first axial side (34) of the support (22) in such a way that a radially outer end section (46) of the heating section (44) which is in the region of the peripheral region (24) of the support (22) and a radially inner end section (48) of the heating section (44) which is in the region of the central region (26) of the support (22) are arranged axially offset with respect to one another.)

1. An exhaust gas heater for an exhaust apparatus of an internal combustion engine, the exhaust gas heater comprising:

-a support (22) having a peripheral zone (24) and a central zone (26) arranged radially externally with respect to a longitudinal axis (A) of the heater,

-a heat conductor (42) supported on the support (22),

wherein the heat conductor (42) comprises a helically wound heating section (44) provided on a first axial side (34) of the support (22),

characterized in that the central region (26) is arranged axially offset with respect to the outer circumferential region (24) in the direction of the first axial side (34) of the carrier (22) such that a radially outer end section (46) of the heating section (44) in the region of the outer circumferential region (24) of the carrier (22) and a radially inner end section (48) of the heating section (44) in the region of the central region (26) of the carrier (22) are arranged axially offset with respect to one another.

2. The exhaust gas heater according to claim 1, characterized in that the bracket (22) comprises a support area (28) extending between the peripheral area (24) and the central area (26) and substantially supporting the heating section (44), and that the support area (28) has a conical shape.

3. The exhaust gas heater according to claim 1 or 2, characterized in that the central region (26) is convexly curved in the direction of the first axial side (34).

4. Exhaust gas heater according to any one of the preceding claims, characterised in that the bracket (22) is constructed as a metal component, preferably a sheet metal shaped piece.

5. Exhaust gas heater according to any one of the preceding claims, characterised in that the thermal conductor (44) is electrically insulated in the region of its length covering the support (22).

6. The exhaust gas heater according to the preamble of claim 1 or according to any of claims 1 to 4, characterized in that the heat conductor (42) is substantially electrically uninsulated in its length region covering the support (22), and in that a plurality of insulating elements (64) which surround the heat conductor and are fixed or/and supported on the support (22) are provided on the heat conductor (42).

7. The exhaust gas heater according to any one of the preceding claims, characterized in that the carrier (22) has a plurality of connecting webs (36) which are arranged at a circumferential distance from one another and connect the central region (26) to the outer circumferential region (24), wherein flow-through openings (38) are formed between connecting webs (36) which are directly adjacent to one another in the circumferential direction.

8. The exhaust gas heater according to claim 7, characterized in that successive flow-through openings (38) in the circumferential direction provide a plurality of radially staged open annular structures (40).

9. The exhaust gas heater according to claim 7, wherein successive flow openings in the circumferential direction provide an open spiral configuration.

10. The exhaust gas heater according to claim 9, characterized in that the helical course of the open helix substantially corresponds to the helical course of the heating section (44), and the heating section (44) is arranged with respect to the open helix such that the heating section (44) is arranged substantially covering the flow-through opening of the open helix.

11. The exhaust gas heater according to claim 9, characterized in that the helical course of the open helix substantially corresponds to the helical course of the heating section (44), and the heating section (44) is arranged with respect to the open helix such that the heating section (44) is arranged substantially without covering the flow-through opening of the open helix.

12. The exhaust gas heater according to one of claims 7 to 11, characterized in that the heat conductor (42) comprises a connecting section (52) which is connected to a radially inner end section (48) of the heating section (44), wherein the connecting section (52) is guided along a connecting web (36) on a second axial side (54) of the carrier (22) from radially inner to radially outer.

13. Exhaust gas heater according to claim 6 and any of claims 7 to 12, wherein a first group (G) arranged extending radially from the outside to the inside is provided on the heat conductor (42) in the region of the connection tab (36)₁) An insulating element (64), wherein the first group (G)₁) The insulating element (64) of the insulating element (64) surrounds a section of the heating section (44) which extends in the region of the connecting web (36).

14. Exhaust gas heater according to claim 13, characterised in that in at least two first groups (G) directly succeeding in the circumferential direction₁) At least one second group (G) extending from the radial outer part to the radial inner part is arranged between the insulating elements (64)₂) An insulating element (64), wherein the second group (G)₂) The insulating element (64) of the insulating element (64) surrounds a section of the heating section (44) which extends in the region between the two connecting webs (36).

15. Exhaust gas heater according to any one of the preceding claims, characterised in that the heating section (44) is held on the holder (22) by a plurality of preferably comb-shaped holding elements (62) which are overlapped by the heating section and are fixed on the holder.

16. Exhaust gas heater according to claim 13 and claim 15, wherein said heating section (44) is in at least one, preferably each first group (G)₁) The insulating element (64) is held on the carrier (22) by means of a holding element (62) in the region thereof.

17. The exhaust gas heater according to any one of the preceding claims, characterized in that a plurality of fastening sections (30) bent in the axial direction for fixing the bracket (22) to the exhaust gas guide member (12) are provided on the outer circumferential region (24) of the bracket (22).

18. The exhaust gas heater according to claim 17, characterized in that at least a part, preferably all, of the fastening section (30) is curved in the direction of the first axial side (34).

19. Exhaust device comprising a preferably tubular exhaust gas guide part (12) and an exhaust gas heater (14) according to any one of the preceding claims arranged in the exhaust gas guide part (12).

20. Exhaust gas system according to claim 19, characterized in that the exhaust gas heater (14) is arranged in the exhaust gas guide (12) with its heater longitudinal axis (a) extending substantially in the direction of the main exhaust gas flow direction (H) such that the support (22) is oriented with its first axial side (34) in the upstream direction such that a radially inner end section (48) of the heating section (44) in the region of the central region (26) of the support (22) is positioned upstream with respect to a radially outer end section (46) of the heating section (44) in the region of the outer circumferential region (24) of the support (22) or/and the heating section (44) is not covered by the support (22) on its side oriented in the upstream direction.

21. An exhaust arrangement according to claim 19 or 20, characterized in that the exhaust heater (14) is arranged upstream with respect to an exhaust treatment unit, preferably a catalyst unit, arranged in the exhaust gas guiding member (12).

Technical Field

The invention relates to an exhaust gas heater for an exhaust gas system of an internal combustion engine, which exhaust gas heater can be used in particular for heating exhaust gas to be flowed onto a catalytic converter unit.

Background

EP2935996B1 discloses an exhaust gas heater, in which a support fixed to a tubular exhaust gas guide element is shaped in such a way that a helically wound heat conductor supported on the support is arranged in an oriented manner in a plane substantially orthogonal to the exhaust gas flow direction.

Disclosure of Invention

The object of the present invention is to design an exhaust gas heater such that it has improved heating properties with increased strength.

According to the invention, this object is achieved by an exhaust gas heater for an exhaust gas system of an internal combustion engine, comprising:

a support having a peripheral zone disposed radially outwardly with respect to the longitudinal axis of the heater and a central zone,

-a thermal conductor supported on the support,

wherein the thermal conductor comprises a helically wound heating section disposed on a first axial side of the support.

This exhaust gas heater is characterized in that the central region is arranged axially offset with respect to the outer circumferential region in the direction of the first axial side of the holder, such that a radially outer end section of the heating section in the region of the outer circumferential region of the holder and a radially inner end section of the heating section in the region of the central region of the holder are arranged offset with respect to one another in the axial direction.

In the exhaust gas heater constructed according to the invention, both the carrier and the heating section of the heat conductor supported on the carrier have a structure which extends axially in its extension from a radially outer portion to a radially inner portion. By means of this axially extending winding configuration of the heat conductor, a greater extension and therefore a stronger thermal interaction of the heat conductor with the exhaust gas circulating it is achieved with the same number of turns with respect to the configurations known in the prior art in which the heating sections of the heat conductor lie substantially in one plane. The axially extending structure of the stent makes it stiffer, in particular in the axial direction, than a stent lying substantially in one plane and thus leads to an increased natural frequency of the stent. The risk of fatigue, which may lead to damage, occurring to the support due to the vibrations that inevitably occur in the exhaust system over the operating life by the oscillation excitation can thus be significantly reduced.

To provide this axially extending structure, the support may comprise a support region extending between the peripheral region and the central region and substantially supporting the heating section, the support region having a substantially conical shape. It is to be noted that: in the sense of the present invention, such a conical or funnel-like shape can be provided, for example and preferably, in such a way that the bearing region has a substantially unbent course in its extension from the radially outer portion to the radially inner portion. However, such a shape can also be realized with a curved course of the bearing region, for example in the shape of a parabola or a hyperbola.

In order to reduce the flow resistance introduced by the stent, the central region may be convexly arched in the direction of the first axial side.

In order to design the exhaust gas heater in a manner that is resistant to aggressive components and high thermal loads of the exhaust gas flowing through the exhaust gas heater, it is proposed that the support be designed as a metal component, preferably as a sheet metal shaped part.

In order to avoid electrical short circuits in the region of the exhaust gas heater, the thermal conductor can be electrically insulated in the region of its length which covers the holder.

In an alternative embodiment, which can form an independent aspect of the invention independently of the shape of the holder and leads to a further improved thermal interaction of the heat conductor with the exhaust gas circulating it, the heat conductor can be substantially electrically uninsulated in its longitudinal region covering the holder, wherein a plurality of insulating elements enclosed by the heat conductor and fixed or/and supported on the holder are provided on the heat conductor. Only in the regions where contact with the heat conductor is unavoidable for the purpose of producing the holding or supporting effect is the heat conductor thus insulated by the provision of the insulating element and therefore also protected from direct contact with the exhaust gas flow. Such a design of the heat conductor can be used not only when the holder is designed to be axially extended, for example conically, and at the same time when the outer and inner end sections of the heating section are axially offset relative to one another, but also in holders having a flat, substantially unbent central region, for example substantially orthogonally to the longitudinal axis of the heater, so that the radially outer and inner end sections of the heating section are also not substantially axially offset relative to one another.

In order to provide a connection between the peripheral region and the central region while ensuring the flow-through properties of the stent, it is proposed that: the support has a plurality of connecting webs which are arranged at a circumferential distance from one another and connect the central region to the outer circumferential region, wherein flow-through openings are formed between connecting webs which are directly adjacent to one another in the circumferential direction.

In this case, a plurality of radially stepped open ring structures can be provided for successive flow openings in the circumferential direction. Such a ring-shaped configuration of the flow-through openings results in the presence of areas of the flow-through openings which are covered by the heating section and areas of the flow-through openings which are not covered by the heating section, which flow-through openings flow through the openings, due to the helical configuration of the heating section. A coordinated design with regard to as little flow resistance as possible on the one hand and as little heat input as possible into the holder on the other hand can thus be achieved.

In an alternative embodiment, it is proposed that: successive flow openings in the circumferential direction provide an open spiral structure.

The helical course of the open helix may substantially correspond to the helical course of the heating section, and the heating section may be arranged in relation to the open helix such that the heating section is arranged substantially over the flow-through opening of the open helix. In this embodiment, the aim is to create as little thermal interaction as possible between the heating section and the holder, so that heat losses through the holder can be minimized.

In an alternative embodiment, it is proposed that: the helical course of the open helix substantially corresponds to the helical course of the heating section, and the heating section is arranged in relation to the open helix such that the heating section is arranged substantially without covering the flow-through openings of the open helix. In this embodiment, preference is given to good flow through the openings, so that the flow resistance introduced by the exhaust gas heater can be minimized.

In order to connect the heat conductor with its two connection regions to the power supply, it is proposed that the heat conductor comprises a connection section which is connected to a radially inner end section of the heating section, wherein the connection section is guided on the second axial side of the carrier from the radially inner side to the radially outer side along a connection tab. By guiding the connection section along the connection web, the influence of the throughflow of the exhaust gas heater, which is introduced through the connection section, is avoided.

In this case, the heat conductor can be held stably on the carrier by providing a first group of insulating elements on the heat conductor in the region of the connection web, said insulating elements extending radially from the outside to the inside, wherein the insulating elements of the first group of insulating elements surround the section of the heating section extending in the region of the connection web.

A further improved holding or supporting effect is achieved if at least one second group of insulating elements, which is arranged to extend radially from the outside to the inside, is arranged between at least two first group of insulating elements which are directly successive in the circumferential direction, wherein the insulating elements of the second group of insulating elements surround a section of the heating section which extends in the region between the two connecting webs.

In order to fix the heat conductor to the carrier, the heating section can be held on the carrier by a plurality of preferably comb-shaped holding elements which are overlapped by the heating section and fixed to the carrier.

In particular in the case of a design of the heat conductor which is not substantially electrically insulated, it is advantageous here that: the heating section is held on the carrier by means of holding elements in the region of at least one, preferably each, first group of insulating elements.

A plurality of fastening sections bent in the axial direction for fixing the bracket to the exhaust gas guide member may be provided on an outer circumferential region of the bracket.

In this case, a design saving axial installation space can be ensured in that at least a part, preferably all, of the fastening sections are bent in the direction of the first axial side.

The invention also relates to an exhaust system comprising a preferably tubular exhaust gas guide part and an exhaust gas heater according to the invention arranged in the exhaust gas guide part.

In this case, the exhaust gas heater can be arranged on the exhaust gas guide part, for example, with its heater longitudinal axis extending substantially in the direction of the main exhaust gas flow direction, in such a way that the holder is oriented with its first axial side in the upstream direction in such a way that the radially inner end section of the heating section in the region of the central region of the holder is positioned upstream with respect to the radially outer end section of the heating section in the region of the outer circumferential region of the holder or/and the heating section is not covered by the holder on its side oriented in the upstream direction.

In order to be able to use the heat input into the exhaust gas via the heat conductor efficiently, it is proposed that: the exhaust gas heater is arranged upstream with respect to an exhaust gas treatment unit, preferably a catalytic converter unit, arranged in the exhaust gas guide.

Drawings

The present invention is described in detail below with reference to the accompanying drawings. In the drawings:

fig. 1 shows a perspective view of a part of an exhaust gas apparatus for an internal combustion engine, the exhaust gas apparatus having an exhaust gas heater;

fig. 2 shows a longitudinal section through the part of the exhaust system shown in fig. 1, taken along the lines II to II in fig. 3;

FIG. 3 shows an axial view of the portion of the axial apparatus shown in FIG. 1;

FIG. 4 illustrates the thermal conductor of the exhaust gas heater illustrated in FIGS. 1-3;

fig. 5 shows a bracket of the exhaust gas heater shown in fig. 1 to 3;

FIG. 6 shows a representation of a part of an exhaust system with an alternative design of an exhaust gas heater, corresponding to FIG. 1;

FIG. 7 shows a perspective view of the exhaust gas heater of FIG. 6;

FIG. 8 shows a retaining element used in the exhaust gas heater of FIG. 7;

FIG. 9 shows another illustration corresponding to FIG. 1 with an alternative design version of the exhaust gas heater;

FIG. 10 illustrates the thermal conductor of the exhaust heater of FIG. 9;

FIG. 11 shows an enlarged region of a thermal conductor having an insulating element surrounding its heating section;

FIG. 12 shows a perspective view of an alternative design version of a thermal conductor that is not electrically insulated;

figure 13 shows a longitudinal section of the thermal conductor of figure 12.

Detailed Description

Fig. 1 to 3 show a section of an exhaust system, generally designated 10, of an internal combustion engine, in particular in a vehicle. The exhaust system 10 comprises an exhaust gas guide component 12, which is designed, for example, as an exhaust gas pipe, in which an exhaust gas heater 14 is arranged in the illustrated length region and a catalytic converter unit 16, which represents one example of an exhaust gas treatment unit, is arranged downstream in the exhaust gas main flow direction H with respect to the exhaust gas heater 14. The catalyst unit 16 may comprise a catalyst block 18 coated with a catalytically effective material, which is held stably in the exhaust gas conducting member 12, for example by a fibre mat 20 or the like.

The exhaust gas heater 14 comprises a support 22 which is shown in fig. 5 and is configured, for example, as a sheet metal shaped part. The support 22 has an outer peripheral region 24 radially outward of the heater longitudinal axis a and a central region 26 centered about the heater longitudinal axis a. Extending between the peripheral region 24 and the central region 26 is a support region, generally indicated at 28, of the stent 22. This support region 28 has a substantially conical or funnel-shaped form, so that the outer peripheral region 24 and the central region 26 are axially offset relative to one another in the direction of the longitudinal axis a of the heater. The conical shaping of the bearing region 28 can be provided, as is illustrated in fig. 2 for this purpose, between the peripheral region 24 and the central region 26 with a substantially straight and unbent extension of the bearing region 28. However, in the sense of the present invention, this conical structure of the bearing region 28 can also be provided by a curved course of the bearing region 28, for example curved at least in some regions convexly or at least in some regions concavely with respect to the main exhaust-gas flow direction H.

In the radially outer region of the carrier 22, starting from the outer circumferential region 24, the carrier has a plurality of fastening sections 30. These fastening sections are bent axially and bear against the inner circumferential surface 32 of the exhaust gas conducting part 12 and are fixed thereto, for example by welding or soldering. In the exemplary embodiment shown in fig. 1 to 5, the fastening section 30 is bent axially in a direction away from the first axial side 34 of the support 22 or its bearing region 28. In fig. 2 can be seen: this first axial side 34 of the carrier 22 is arranged in the upstream direction, i.e. oriented facing the exhaust gas flow to be flowed onto the exhaust gas heater.

Fig. 5 also shows: in the illustrated embodiment of the support 22, a total of four connecting webs 36 connect the outer circumferential region 24, which is of annular design, for example, to the central region 26, which is preferably convexly arched in the direction of the first axial side 34 of the support 22, i.e., in the upstream direction. Here, each of the four connecting webs 36 may extend substantially linearly from the radially outer portion to the radially inner portion.

Between two connecting webs 36 which are respectively directly adjacent to one another in the circumferential direction, a plurality of flow-through openings 38 which are respectively separated by a circumferential web 39 which extends substantially in the circumferential direction between the two connecting webs are formed in a radially stepped manner. In the illustrated embodiment, the flow openings 38 are designed in the form of ring segments, and the flow openings 38 which follow one another in the circumferential direction each form an opening ring structure 40. In fig. 4 can be seen: a plurality of such open ring structures 40 are radially staged and preferably concentrically disposed about the heater longitudinal axis a.

Exhaust heater 14 also includes a thermal conductor 42, shown in detail in FIG. 4. Heat conductor 42 has a heating section 44 which is arranged on first axial side 34 of support 12 or of its bearing region 28. In this heating section 44, the heat conductor 42 extends in a spirally wound configuration starting from a radially outer end section 46 located in the region of the outer circumferential region 24 of the support 22 toward a radially inner end section 48 located in the region of the central region 26. In accordance with the axially extending configuration of the carrier 22, the heating section 44 is also axially extended, so that the radially outer end section 46 and the radially inner end section 48 are axially offset relative to one another and the heating section 44 therefore has a conical configuration of its coils which is adapted to the conical configuration of the bearing region 28.

Heat conductor 42 rests with its heating section 44 in the region of support region 28 against first axial side 34 of support 22 and is fixed thereto in a manner to be described below. In the region of the central region 26 of the carrier 22, openings 50 are formed which are provided for the passage of the heat conductors 42 and through which the heat conductors 42 are guided in the region in which the heating section 44 transitions into the connecting section 52 in the region of the radially inner end section 48. The connecting section 52 extends radially outward from the radially inner end section 48 along one of the connecting webs 36 on the second axial side 54 of the carrier 22, so that a first connecting section 56 connected to the radially outer end section 46 and a second connecting section 58 connected to the connecting section 52 are positioned radially outward with respect to the heating section 44 and are guided through the exhaust gas guide component 12 in the region of the insulating element 60.

Due to the helical course of the heating sections 44 and the design of the flow openings 38 providing the radially stepped split ring structures 40, the heating sections 44 have a course, which is visible in the axial view of fig. 3, with respect to these split ring structures 40. When viewed in the direction of the heater longitudinal axis a, as also when viewed in a direction perpendicular to the surface of the bearing region 28 on the first axial side 34, the heating section 44 covers the flow-through opening 38, i.e. the region which is therefore not in contact with the bearing region 28, and the region in which the heating section 44 does not cover the flow-through opening 38, but is now in contact with the bearing region 28 of the carrier 22. Thus, on the one hand, the flow resistance for the exhaust gas flowing in the main exhaust gas flow direction H onto the exhaust gas heater 14 is not increased excessively, and on the other hand, an excessively strong contact between the heat conductor 42 and the carrier 22 and thus an excessive heat input into the carrier 22 are avoided. Since the connecting section 52 extends radially outward along one of the connecting webs 36 on the second axial side 54, this connecting section does not substantially influence the throughflow of the exhaust gas heater.

In order to avoid the formation of electrical short circuits in the region of direct contact of the heat conductor 52 with the carrier 22, which is preferably provided as a sheet metal molding, the heat conductor 52 is electrically insulated in the design example shown in fig. 1 to 5 between the two connecting sections 56, 58 substantially over its entire length.

Due to the axially extending conical or conical shape of the exhaust gas heater 14, a relatively large extent of the heat conductor 42 in the exhaust gas flow can be achieved in a compact design, so that this heat conductor can provide a large heating power and thus an effective heating of the exhaust gas flow to be flowed onto the catalytic converter unit 16. This ensures that: in the operating phase, for example, a cold start, rapid heating of the catalytically effective material is also achieved, so that the duration until which the catalytic converter unit cannot be catalytically effective due to excessively low temperatures is shortened. While the axially extending conical configuration of the holder 22 provides a configuration in which the exhaust gas heater 14 has a high stiffness, particularly in the direction of the heater longitudinal axis a. The vibrations occurring during operation of the internal combustion engine and inevitably also transmitted to the exhaust system 10 can therefore, due to the increased natural frequency of the carrier 22, substantially not result in oscillation excitations which can lead to fatigue and damage to the carrier 22 over the operating life. The axially extending, radially outer tapering structure of the exhaust gas heater 14 in the upstream direction from the radially outer side to the radially inner side furthermore makes it possible to position the exhaust gas heater 14 in the exhaust gas guide part 12 in such a way that the exhaust gas heater 14 projects locally in the upstream direction from the exhaust gas guide part 12 and engages into an interior space which is provided by a further exhaust gas guide part 62 of likewise conical structure connected thereto on the upstream end of the exhaust gas guide part 12. Therefore, no contact or excessive constriction of the flow cross sections occurs in the region of these further exhaust gas conducting elements 62.

An alternative design of the exhaust gas heater 14 is shown in fig. 6 to 8. As is evident in fig. 6 and 7: the support 22 of this exhaust gas heater 14 is designed in its radially outer region in such a way that the fastening section 30 extends axially in the direction of the first axial side 34 of the support 22, i.e. in the upstream direction. This results in: the fastening section 30 overlaps the bearing region 28 of the carrier 22 in the axial direction, which results in a shorter axial design and enables the exhaust gas heater 14 to be positioned closer to the catalytic converter unit 18.

Fig. 6 to 8 also show: in which way and method the heat conductor 42 can be fastened to the support 22, in particular in the region of its heating section 44. For this purpose, a plurality of comb-shaped holding elements 62 can be provided, wherein, for example, one such holding element 62 can be provided associated with each connecting web 36 of the carrier 22.

The holding element 62 overlaps the heating section 44 of the heat conductor 32 in a section of the heat conductor that extends in the region of the connection web 36 and is fastened to the mount 22, for example by welding or soldering, for example in the radially outer and radially inner end regions of the holding element or/and in the region of the heating section 44 that engages between the respective coils.

It is to be noted that: it goes without saying that, in the embodiment shown in fig. 1 to 5, the heat conductor 32 can be fastened to the holder 22 with its heating section abutting against the first axial side 34 of the holder 22, using such a holding element 62.

Fig. 9 to 11 show a further alternative embodiment of the exhaust gas heater 14. In this embodiment, heat conductor 42 is not electrically insulated substantially over its entire length extending between connection sections 56, 58. This ensures the thermal conductor 42 and theretoBetter thermal interaction of the circulating exhaust gases. In order to nevertheless be able to hold the heat conductor 42 stably, for example using the holding element 42 that can be seen in fig. 8, on the holder 22 that can be designed as described above, a first group G is provided, which surrounds the heat conductor 42, associated with the connecting web 36 that can be seen in fig. 5, for example₁An insulating element 64. As is apparent from fig. 10 and 11 to this point, the four first groups G₁Are arranged with respect to the respective sections of the heating sections 44 of the heat conductors 42 surrounding one another in such a way that the first group G₁A line extending from the radially outer portion to the radially inner portion along the course of the connection tab 36. Direct physical contact of the thermal conductor 42 with the carrier 22 constructed from a metallic material is thus avoided. For fastening to the connecting web 36, the retaining element 62 shown in fig. 7 can overlap the first group G₁The insulating element 64 of the insulating element is provided in the form of an insulating element and is fastened to the connecting web 36 in a material-locking manner.

In a first group G of two directly adjacent groups in the circumferential direction₁A second group G is arranged between the connecting elements 64₂A connecting element 64. In the second group G₂The connecting elements 64 are also arranged linearly extending from the radially outer portion to the radially inner portion. It is also possible to use a holding element similar to that shown in fig. 8 in these regions. In principle, the second group G₂The insulating element 64 of (a) may also serve merely to ensure the axial support of the heating section 44 relative to the carrier 22, so that vibrations occurring during operation of the internal combustion engine and transmitted to the exhaust gas heater do not lead to: inadvertent contact is made between the non-electrically insulated thermal conductor 42 and the support 22.

First group G₁And a second group G₂The insulating element 64 of (a) may, for example, comprise a housing 66 constructed in a metallic material, for example stainless steel or the like, the inner space of which, which is penetrated by the thermal conductor 42, may be filled with an electrically insulating material 68, for example magnesium oxide, a thermally durable and gas-resistant plastic material or the like.

It is to be noted that: the exhaust gas heater previously described in detail with respect to fig. 1 to 11 may vary in very different respects. Thus, the carrier can have, for example, a further number of connecting webs connecting the central region to the peripheral region, and the connecting webs can have a different, for example curved, extension than the straight extension. The number of flow-through openings formed between the connecting webs can also be selected differently than is shown in the figures.

The flow openings can in particular also be designed such that successive flow openings in the circumferential direction do not form an open ring structure, which is arranged concentrically with respect to one another, but rather form an open spiral structure. Such an open spiral can be adapted in its course to the spiral course of the heating section, so that, for example, such a positioning of the heating section with respect to this open spiral can be predetermined that the heating section 44, for example when viewed in the axial direction or when viewed orthogonally to the outer surface of the bearing region of the holder, substantially covers the open spiral and therefore has little direct contact with the holder, so that a heat input from the heat conductor into the holder can be minimized. In an alternative embodiment, provision can be made for: the heating section is arranged with its spiral structure substantially not covering the open spiral structure, so that the open spiral structure has good throughflow properties for the exhaust gas, while the heating section with its spiral shape of the thermal conductor then has an enhanced thermal interaction with the carrier over a larger length area. The coordinated design can also be selected in such a way that the flow-through openings or bearing areas of the carrier are selected by the covering of the heating sections in such a way that, on the one hand, good throughflow of the exhaust gas for the flow in the direction of the catalytic converter unit is ensured and, on the other hand, excessive heat input into the carrier is also avoided.

An alternative design of heat conductor 42 is shown in fig. 12 and 13. The heat conductor 42 and the support 22 here correspond, for example, to the previously described embodiment with regard to the helically wound structure of the heating section 44 of the heat conductor 42 and also with regard to the design of the central region 26 of the support 22, together with the connection webs 36 and the flow openings 38 formed therebetween and the open ring structure 40 formed with the flow openings or alternatively the open spiral structure.

However, in the embodiment of fig. 12 and 13, the heat conductors 42, which are also substantially not electrically insulated, do not extend axially, so that the radially outer end section 46 of the heating section 44 and the radially inner end section 48 of the heating section 44, for example, lie substantially in a plane orthogonal to the heater longitudinal axis a and the spiral structure of the heating section 44 also, independently of the axial extension of the heating section 44, lies, for example, in a plane orthogonal to the heater longitudinal axis a. On the side of the heat conductor 42 or of its heating section 44 oriented in the downstream direction, a central region 26 of the support 22 is provided, which is likewise of substantially planar design. Heat conductors 42 can be arranged, for example, again in first group G so as to partially surround heating section 44₁And a second group G₂The insulating element 64 in (a) abuts against the central region 26, wherein the arrangement may again be such that the first group G, for example, abuts against the central region 26₁The insulating element 64 may extend along the corresponding connecting tab of the bracket 22. For fastening the heat conductor 42 to the support 22, for example, a comb-shaped holding element 62 shown in fig. 6 to 8 can be used, which can be fastened to the central region 26 of the support 22 with its tabs engaging between the radially stepped winding sections of the heating section 44.

In this embodiment, the advantage of a very effective thermal interaction of the heat conductor 42 with the exhaust gas circulating the heat conductor is also obtained in a compact axial design, due to the electrical insulation of the heat conductor 42 which is essentially absent in the region of its heating section 44, wherein in this embodiment too, for such a good thermal interaction, it is advantageously provided: the heating conductor 42 is arranged with its heating section 44 on the side of the central region 26 of the support 22 oriented in the upstream direction and on the side thereof oriented in the upstream direction is not covered or protected from the inflow of exhaust gas by the region 22 of the support.