Heating device

Abstract

Heating device for an exhaust system of an internal combustion engine, comprising a support arrangement (18) and at least one heating conductor element (20) mounted on the support arrangement (18) so that gas can flow through it in the direction of a heating device longitudinal axis (L), wherein the support arrangement (18) comprises a first support element (37) arranged on a first axial side of the at least one heating conductor element (20), a second support element (41) arranged on a second axial side of the at least one heating conductor element (20) and a support element connection area (44) connecting the first support element (37) with the second support element (41) and extending radially outward and axially overlapping the at least one heating conductor element,wherein a first electrically insulating bearing material (47) is arranged between the first support element (37) and the at least one heating conductor element (20), and a second electrically insulating bearing material (48) is arranged between the second support element (41) and the at least one heating conductor element (20), wherein the at least one heating conductor element (20) has a plurality of heating conductor sections (22, 28, 30), wherein a gap (24) is formed between adjacent heating conductor sections (22, 28, 30), and at least a part of the heating conductor sections (22) connects to an adjacent heating conductor section (22, 28, 30) in a heating conductor section connection area (26) in a heating conductor section longitudinal end region, and / or connects to another adjacent heating conductor section (22, 28, 30) in a heating conductor section connection area (26) in another heating conductor section longitudinal end region, characterized in thatthat the first electrically insulating bearing material (47) extends into at least one space (24) formed between adjacent heating conductor sections (22, 28, 30) and / or adjacent heating conductor section connection areas (26), and / or that the second electrically insulating bearing material (48) extends into at least one space (24) formed between adjacent heating conductor sections (22, 28, 30) and / or adjacent heating conductor section connection areas (26).

Description

[0001] The present invention relates to a heating device for an exhaust system of an internal combustion engine according to the preamble of claim 1.

[0002] Such heating devices are used in exhaust systems to warm the gas flowing within the system, for example, the exhaust gas emitted by an internal combustion engine. Particularly during the start-up phase of an internal combustion engine's operation, when the exhaust gas has a comparatively low temperature, the heat absorbed by the heating device in the exhaust gas can be transferred to a downstream exhaust gas treatment system, such as a catalytic converter or particulate filter. This allows for rapid heating of the exhaust gas treatment system and significantly reduces the time during which exhaust gas is released into the environment without undergoing a cleaning process, such as a catalytic one.

[0003] From US Patent 5,597,503 A, a heating device according to the preamble of claim 1 is known, in which a substantially disc-shaped heating conductor element comprises a plurality of substantially parallel, elongated heating conductor sections. In one of their longitudinal end regions, the heating conductor sections connect to an adjacent heating conductor section in a heating conductor connection region. In the other of their longitudinal end regions, the heating conductor sections connect to another heating conductor section in a heating conductor section connection region, so that a substantially meandering structure of the heating conductor sections is generally obtained.The last two heating conductor sections of this meandering structure each provide a heating conductor element connection area, in which a contact element penetrating a housing-like exhaust gas guide element connects to the respective heating conductor element connection area and thus establishes an electrical connection with a voltage source.

[0004] The disc-shaped heating element is supported in its radially outer region by a support arrangement, which is generally designed with a ring-like structure. This support arrangement includes an upstream support ring on the upstream side of the heating element, which radially overlaps the heating element in its radially outer region. On the downstream side of the at least one heating element, a downstream support ring of the support arrangement is arranged radially overlapping the heating element in its radially outer region. The two support rings are rigidly connected to each other by a support ring connection area formed by the exhaust gas routing component. Bearing material is arranged between the support rings and the radially outer region of the heating element, and also between the radially outer region of the heating element and the support ring connection area. This bearing material electrically insulates the heating element and holds it on the support arrangement.

[0005] From DE 10 2020 123 376 A1, an exhaust gas heater is known in which a radially outer region of a heating conductor extending in a meandering coil field is axially held between the radially outer regions of disk-like support elements with intermediate support of ring-like insulating elements. One of the insulating elements overlaps the heating conductor, and the other insulating element overlaps it radially outside.

[0006] The object of the present invention is to provide a heating device for an exhaust system of an internal combustion engine, in which the at least one heating element mounted on the support arrangement is held in a defined position.

[0007] According to the invention, this problem is solved by a heating device for an exhaust system of an internal combustion engine, comprising a support arrangement and at least one heating conductor element mounted on the support arrangement so that gas can flow through it in the direction of a heating device longitudinal axis, wherein the support arrangement comprises a first support element arranged on a first axial side of the at least one heating conductor element, a second support element arranged on a second axial side of the at least one heating conductor element and a support element connection area connecting the first support element to the second support element and radially overlapping the at least one heating conductor element axially on the outside.wherein first electrically insulating bearing material is arranged between the first support element and the at least one heating conductor element, and second electrically insulating bearing material is arranged between the second support element and the at least one heating conductor element, wherein the at least one heating conductor element is, for example, disk-shaped and has a plurality of heating conductor sections, wherein a gap is formed between adjacent heating conductor sections, and at least a part of the heating conductor sections connects to an adjacent heating conductor section in a heating conductor section connection area in a heating conductor section longitudinal end area, and / or connects to another adjacent heating conductor section in a heating conductor section connection area in another heating conductor section longitudinal end area, characterized in thatthat the first electrically insulating bearing material extends into at least one gap formed between adjacent heating conductor sections or / and adjacent heating conductor section connection areas, or / and that the second electrically insulating bearing material extends into at least one gap formed between adjacent heating conductor sections or / and adjacent heating conductor section connection areas.

[0008] The bearing material, extending into the gap, creates a positive fit between itself and the heating element. In addition to the frictional fit generated by the compressed or pre-tensioned installation of the bearing material between the bearing material and the heating element on the one hand, and between the bearing material and the support assembly on the other, this positive fit contributes to increased stability of the heating element's mounting on the support assembly, taking into account, for example, the mechanical and thermal loads occurring in a vehicle. The resulting holding interaction is resistant to corrosive media and deposits that form during operation, and is unaffected by the electric current flowing through the heating element.

[0009] For a holding interaction that is essentially uniform across the circumference, it is proposed that the first bearing material comprises a first bearing material ring that essentially completely surrounds the longitudinal axis of the heating device, and / or that the second bearing material comprises a second bearing material ring that essentially completely surrounds the longitudinal axis of the heating device. Furthermore, electrical contact for the at least one heating element that is essentially unaffected by the bearing material can be provided if the heating element is not axially covered by bearing material on its outer circumferential surface.

[0010] In order to achieve good electrical insulation performance with equally good corrosion resistance, it is proposed that the first bearing material be made up of preferably ceramic fiber material, and / or that the second bearing material be made up of preferably ceramic fiber material.

[0011] For an essentially meandering structure of the heating conductor sections of the heating conductor element, at least a part of the spaces, preferably all spaces, can be closed off in a first space longitudinal end area by a heating conductor section connection area and be open in a second space longitudinal end area.

[0012] Further increased stability in the mounting of the at least one heating conductor element can be achieved through the positive locking mechanism if at least part of the gaps, preferably all gaps, in the second gap longitudinal end region is expanded substantially transversely to a gap longitudinal extension direction.

[0013] For this purpose, it can be provided, for example, that at least a part of the gaps, preferably all gaps, in a first gap extension section extending between two heating conductor sections or / and in the first gap longitudinal end region, has a first gap width, and at least a part of a second gap extension section extending along at least one heating conductor section connection region has a second gap width, and that the second gap width is greater than the first gap width.

[0014] In order to ensure that the flow through the at least one heating conductor element via the bearing material is not substantially impaired while maintaining stable mounting, it is proposed that the first bearing material covers at least part of a respective second space extension section and / or does not substantially extend into the area of ​​a respective first space extension section, and / or that the second bearing material covers at least part of a respective second space extension section and / or does not substantially extend into the area of ​​a respective first space extension section.

[0015] The penetration of the bearing material into a given gap can be facilitated by providing a bearing material bearing projection on at least one, preferably each, support element, corresponding to at least one, preferably each, gap. Such a bearing material bearing projection deforms the bearing material, causing it to penetrate and creating a positive fit between the bearing material bearing projection and the bearing material, resulting in a strengthened holding effect.

[0016] In particular, if a respective support element is designed as sheet metal forming parts, at least one, preferably every, bearing material bearing projection can be formed by a shaping of a support element.

[0017] In order to exert the effect of a respective bearing material application protrusion where it is required, it is proposed that at least one, preferably each, bearing material application protrusion extends into the area of ​​at least a part of a second interspace extension section and / or does not substantially extend into the area of ​​a first interspace extension section.

[0018] For a stable mounting while still allowing good flow through the heating conductor element, the support arrangement can be arranged in a ring-like manner around the at least one heating conductor element in a radially outer area.

[0019] In a simple and cost-effective yet corrosion-resistant design, at least one, preferably every, support element can be constructed with sheet metal material, and / or the support element connection area can be formed in one piece with at least one of the support elements.

[0020] The first support element can comprise a substantially radially extending first support element body, wherein at least one, preferably each, bearing material contact projection of the first support element can be provided on the first support element body. Furthermore, the second support element can comprise a substantially radially extending second support element body, wherein at least one, preferably each, bearing material contact projection of the second support element can be provided on the second support element body.

[0021] The invention further relates to an exhaust system for an internal combustion engine, comprising an exhaust gas routing component through which exhaust gas flows in a main exhaust gas flow direction, wherein an exhaust gas treatment arrangement is located in the exhaust gas routing component and at least one heating device constructed according to the invention is located upstream of the exhaust gas treatment arrangement.

[0022] The present invention is described in detail below with reference to the accompanying figures. These show: Fig. 1. A perspective view of a heating device for an exhaust system, viewed from an inflow side; Fig. 2 a detailed longitudinal section view of the heating device of the Fig. 1; Fig. 3 An axial view of a disc-shaped heating conductor element of the heating device of the Fig. 1; Fig. 4 Another detailed sectional view of the heating device Fig. 1; Fig. 5 a perspective view of the heating device of the Fig. 1, viewed from an outflow side; Fig. 6 a schematic sectional view of the heating device; Fig. 7 a detail of the principle sectional view of the Fig. 6 enlarged; Fig. 8 one of the Fig. 7. Corresponding representation of a modified design of the heating device; Fig. 9 another of the Fig. 7. Corresponding representation of a modified design of the heating device; Fig. 10 another of the Fig. 7. Corresponding representation of a modified design of the heating device; Fig. 11 a schematic representation of an exhaust system with a heating device and an exhaust gas treatment arrangement downstream of the heating device.

[0023] The figures show a heating device for a Fig. Figure 11 shows a schematic representation of the exhaust system 10 of an internal combustion engine, generally designated by 12. The heating device 12 is arranged in the exhaust system 10 in an exhaust gas routing component 14, for example, a pipe-like or housing-like component, in the main exhaust gas flow direction A upstream with respect to an exhaust gas treatment arrangement generally designated by 16. The exhaust gas treatment arrangement 16 can, for example, comprise a catalyst unit, such as an SCR catalyst, a particulate filter unit, or the like. In such an exhaust gas treatment arrangement 16, the exhaust gas flowing towards the heating device 12 and the exhaust gas treatment arrangement 16 in the main exhaust gas flow direction A is cleaned of pollutants contained therein, for example, in a catalytic reaction.

[0024] The heating device 12 comprises a support arrangement, generally designated 18, which surrounds a heating device longitudinal axis L in a ring-like manner. A [missing information] is attached to the support arrangement 18. Fig. Figure 3 shows the heating element 20 in axial view, mounted such that exhaust gas flowing in the main exhaust gas flow direction A or in the direction of the heating device's longitudinal axis L can pass through it. The heating element 20 is cut from an electrically conductive flat material, for example by laser cutting or the like, and has a fundamentally disc-like structure.

[0025] The heating conductor element 20 has a plurality of essentially straight and parallel heating conductor sections 22, between which gap-like spaces 24 are formed through which the exhaust gas can flow. In their longitudinal end regions, the heating conductor sections 22 connect to each other in respective heating conductor section connection regions 26, which are integrally formed with them, resulting in a generally meandering structure of the adjacent heating conductor sections 22.

[0026] The heating conductor sections 28, 30, located at the ends of this meandering structure, connect to an adjacent heating conductor section 22 only at one of their longitudinal end regions in a heating conductor section connection area 26, and each provides a heating conductor section connection area 32, 34. In the heating conductor element connection areas 32, 34, the heating conductor element 20, which is heated when an electric current is applied to it, is connected to a voltage source in a vehicle, for example the vehicle's electrical system or a battery, via connection elements 50, 52 and contact elements 86, 88 of a feedthrough 84.

[0027] The spaces 24 formed between adjacent heating conductor sections 22, which lie transversely to the longitudinal axis L of the heating device, are closed in a respective first space-end region 53 by a heating conductor section connection region 26 and are open radially outwards or to an outer circumferential surface 66 of the heating conductor element 20 in a respective second space-end region 55. Starting from the respective first space-end regions 53, a respective first space extension section 68 extends transversely to the respective space-end direction Z with a substantially constant first space width b, which essentially also corresponds to the longitudinal extension direction of the heating conductor sections 22.In the second interspace longitudinal end regions 55, respective second interspace extension sections 70 are formed, in which the interspaces 24 transverse to the interspace longitudinal extension direction Z have a width B that is greater than the width b in the respective first interspace extension sections 68 that follow thereafter.

[0028] The carrier arrangement 18 comprises a Fig. 1. A first support element 37, recognizable at the front and, in the illustrated embodiment, providing an upstream first support ring 36, which attaches the heating conductor element 20 to its Fig. The frontally visible upstream side 38 is covered in its radially outer region. The support arrangement 18 further comprises a second support element 41 providing a downstream second support ring 40, which overlaps the heating conductor element 20 on its downstream side 42 in its radially outer region. For connecting the two support elements 37, 41, a support element connection area, generally designated 44, is provided on the first support element 37, which provides the upstream first support ring 36. This connection area comprises a plurality of support element connection sections 46, spaced apart from one another and extending substantially axially, which overlap the downstream second support ring 40 or the second support element 41 radially outwards in the axial direction and are firmly connected to it, for example, by welding or soldering.The two support elements 37, 41 can be formed, for example, by punching out and forming a respective sheet metal blank.

[0029] For the stable and electrically insulated mounting of the heating element 20 between the two support elements 37, 41, a first bearing material 47 or a second bearing material 48 is arranged between the radially outer region of the heating element 20 and each of the support elements 37, 41. This bearing material is provided, for example, by a first bearing material ring 49 or a second bearing material ring 51, respectively, and extends, for example, along the entire edge region of the heating element 20. The bearing material 47, 48 can, for example, be made of electrically insulating fiber material, such as ceramic material like silicon dioxide or aluminum oxide, and is held under axial preload between each of the support elements 37, 41 and the upstream side 38 or the downstream side 42 of the heating element 20, respectively.

[0030] The support elements 37, 41, designed as support rings 36, 40 in the illustrated embodiment, are constructed with a first support element body 54 and a second support element body 56, respectively, extending essentially radially and circumferentially. Radially on the outside of the first support element body 54, the support element connecting sections 46, which are integrally formed with it (i.e., formed in one piece), are attached. These connecting sections overlap the second support element body 54 of the second support element 41 radially on the outside and are firmly connected to it. Radially on the inside of each of the two support element bodies 54, 56, an axial projection 58, 60 extending towards the heating conductor element 20 is attached. The first axial projection 58 of the first support element 37 overlaps or...The first bearing material 47 partially overlaps axially on its radial inner side, so that a gap-like space 62 is formed between the first axial projection 58 and the upstream side 38 of the heating conductor element 20. Similarly, the second axial projection 60 of the second support element 41 partially overlaps axially on its radial inner side the second bearing material 48, so that a gap-like space 64 is formed between the second axial projection 60 and the downstream side 42 of the heating conductor element 20.

[0031] The two axial projections 58, 60 are integrally formed with their respective support element bodies 54, 56 by bending the latter at its radially inner end region and ensure a defined positioning of the first bearing material 47 and the second bearing material 48 relative to the heating conductor element 20. Simultaneously, the two axial projections 58, 60 shield the first bearing material 47 and the second bearing material 48 radially inwards and protect them from external influences, particularly before the heating device 10 is installed in an exhaust system. The gap-like spaces 62, 64 nevertheless ensure that an electrical short circuit cannot occur between the heating conductor element 20, through which current flows during heating operation, and the support arrangement 18.

[0032] By installing the first bearing material 47 or the first bearing material 49 and the second bearing material 48 or the second bearing material ring 55 under preload or compression, the respective bearing material 47, 48 is pressed into the spaces 24 of the heating conductor element 20 by the application of force via the respective associated support element body 54, 56, since the first or second bearing material 47, 48, which is made of fiber material, is fundamentally flexible and deformable and receives no support in the area of ​​the spaces 24 it covers. The resulting structure is shown in principle in Fig. Figure 6 shows that the first bearing material 47 and the second bearing material 48 form a bearing material bulge 72 or 74 where they cover a respective gap 24 or its second gap extension section 70, respectively, which engages between two adjacent heating conductor sections 22.

[0033] The bearing material bulges 72, 74 thus formed create a positive locking interaction between the first bearing material 47 or the second bearing material 48 and the heating conductor element 20 in the second gap extension sections 70. In addition to the frictional interaction generated by the mutual contact, this ensures increased stability in the mounting of the heating conductor element 20 between the two support elements 37, 41. Since the two bearing material rings 49, 51 are dimensioned radially such that they, for example, only cover the second gap extension sections 70, but do not extend substantially into the area of ​​the first gap extension sections 68, it is ensured that the heating conductor element 20 is permeable, particularly in the area of ​​the first gap extension sections 68.

[0034] The Fig. Figure 7 shows an enlarged view of the area of ​​a second intermediate space extension section 70 or a second intermediate space longitudinal end section 55 with the two bearing material bulges 72, 74 generated on the bearing material rings 49, 51 by the axial loading by means of the support elements 37, 41. It can be seen that these have a fundamentally rounded, convex structure.

[0035] The Fig. Figure 8 illustrates an embodiment in which a bearing material bearing projection 76 is formed in the second support element 41, particularly in the area of ​​the support element body 56, corresponding to at least one, preferably each, gap 24 or second gap extension section 70. The bearing material bearing projection 76 presses the second bearing material 48 more firmly into the second gap extension section 70, thereby creating an even more intensive positive fit between the second bearing material 48 and the heating conductor element 20.

[0036] Each bearing material bearing projection 76 formed in the second bearing element 41 is arranged and dimensioned such that it substantially covers an associated second gap extension section 70, but does not extend into the area of ​​the first gap extension section 68 adjoining it. In this way, it is ensured that such a bearing material bearing projection 76 presses the second bearing material 48 into the gap 24 substantially only in the area of ​​the second gap extension section 70.

[0037] It should be noted that, although this in Fig. 8 not shown, the first bearing material 47 can also be pressed into the second intermediate extension sections 70 covered by the support element body 54 of the first support element 37, which in this embodiment is designed without bearing material bearing projections, as is the case in Fig. Figure 7 illustrates this.

[0038] At the in Fig. In the embodiment shown in Figure 9, bearing material bearing projections 78 are formed only in the support element body 54 of the first support element 37, while the support element body 56 of the second support element 41 is essentially planar, particularly in its area covering the second bearing material 48. It should also be noted here that the second bearing material 48 is located in one of the Fig. 7 in a corresponding manner equally where a respective second space extension section 70 is covered by this, can be pressed into it by the impact of the second support element 42.

[0039] In Fig. Figure 10 shows an embodiment in which bearing material bearing projections 76, 78 are provided in both the first support element 37 and the second support element 41, corresponding to at least a portion, preferably all, of the second intermediate space extension sections 70 or intermediate spaces 24. This creates an even stronger positive fit between the first bearing material 47 and the second bearing material 48 and the heating conductor element 20. At the same time, as in the embodiments of the Fig. 8 and Fig. 9, a positive fit is created by a respective bearing material bearing projection 76, 78 and the bearing material 47, 48 bearing this.

[0040] The bearing material bearing projections 78, 76 formed in the support elements 37 and 41 can be produced in a simple manner, particularly when the support elements 37, 41 are designed as sheet metal forming parts, by forming the sheet metal blanks used to construct the support elements 37, 41, for example when the axial projections 58, 60 are also produced or when the support element connection area 44 with the support element connection sections 46 is produced on the first support element 37.

[0041] It should be emphasized that not every gap 24 necessarily has to have a greater width in its second longitudinal end region 55 than in its respective first longitudinal end region 53. Accordingly, it can also be provided that on one or both support elements 37, 41, bearing material bearing projections 78, 76 are provided only in association with such gaps 24 whose second longitudinal end region 55 has a greater width, in order to support the increased pressing in of the basically flexible or deformable bearing material 47, 48 only where gaps 24 have a greater width.

[0042] The first bearing material 47 and the second bearing material 48 can also be made of other flexible, electrically insulating material, for example foamed material, which is deformed when subjected to an associated support element 37 or 41 and can thereby form a respective bearing material bulge 72 or 74.

[0043] It should further be noted that in the heating device, the support elements positioned axially on both sides of the at least one heating conductor element do not necessarily have to have the continuous ring structure visible in the figures. For example, the support elements can also be provided by several support element sections arranged successively in the circumferential direction, spaced apart from one another, and thus forming a ring-like shape in their entirety, with an axial projection being formed on at least some of the support element sections. Furthermore, in the heating device shown in the figures, for example, more than one heating conductor element may be provided, and the single or possibly several heating conductor elements may have a differently wound path, for example, a spirally wound path of the respective heating conductor sections.

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