HEATING CONDUCTOR FOR AN EXHAUST GAS HEATING ARRANGEMENT

Abstract

A heating conductor for an exhaust gas heating arrangement for an exhaust gas system for an internal combustion engine includes a plurality of heating conductor sections. At least one throughflow opening, preferably a plurality of throughflow openings through which exhaust gas can flow, is or are provided in at least one heating conductor section, preferably in a plurality of heating conductor sections or in each heating conductor section.

Claims

1. A heating conductor for an exhaust gas heating arrangement for an exhaust gas system for an internal combustion engine, the heating conductor comprising: a plurality of heating conductor sections; and, at least one of said plurality of heating conductor sections defining a throughflow opening for passing exhaust gas therethrough.

2. The heating conductor of claim 1, wherein selected ones of said plurality of heating conductor sections define throughflow openings for passing exhaust gas therethrough.

3. The heating conductor of claim 1, wherein said plurality of heating conductor sections define respective throughflow openings therein for passing exhaust gas therethrough.

4. The heating conductor of claim 1, wherein at least a first portion of said plurality of heating conductor sections are arranged to adjoin one another to provide a configuration of the heating conductor in a form of a winding.

5. The heating conductor of claim 4, wherein at least a second portion of said plurality of heating conductor sections are arranged to form a configuration of the heating conductor wound in a meandering manner at least in regions thereof.

6. The heating conductor of claim 4, wherein at least a third portion of the heating conductor sections form a configuration of the heating conductor wound spirally at least in regions thereof.

7. The heating conductor of claim 1, wherein said at least one throughflow opening is elongated in a longitudinal direction (H) of the heating conductor section corresponding thereto.

8. The heating conductor of claim 1, further comprising a flow-conducting element in association with said at least one throughflow opening on said heating conductor.

9. The heating conductor of claim 8, wherein said at least one throughflow opening has a longitudinal end region and defines a longitudinal direction (D); and, said flow-conducting element is configured to extend, starting from said longitudinal end region, in said longitudinal direction (D) beyond said throughflow opening.

10. The heating conductor of claim 8, wherein, at said throughflow opening, said flow-conducting element is offset at least in regions with respect to said heating conductor.

11. The heating conductor of claim 1, wherein at least one of the following applies: i) said heating conductor is configured to be substantially plate-like; and, ii) said heating conductor is cut out from a metal flat material.

12. A method for making a heating conductor for an exhaust gas heating arrangement for an exhaust gas system for an internal combustion engine, the method comprising: a) providing a metal flat material blank; b) cutting out at least one heating conductor having a plurality of heating conductor sections from the metal flat material blank; and, c) providing at least one throughflow opening in at least one heating conductor section of at least one heating conductor.

13. The method as claimed in claim 12, wherein selected ones of said plurality of heating conductor sections are provided with throughflow openings, respectively.

14. The method of claim 12, wherein each of said heating conductor sections is provided with a throughflow opening.

15. The method of claim 12, wherein, in method step b), at least one heating conductor is cut from the metal flat material blank by punching or cutting.

16. The method of claim 12, wherein, in association with the at least one heating conductor, method step c) is carried out together with method step b).

17. The method of claim 12, wherein, with the at least one heating conductor, method step c) is carried out ahead of method step b).

18. The method of claim 12, wherein, in association with the at least one heating conductor, method step c) is carried out after method step b) is carried out, in order to provide the at least one throughflow opening.

19. The method of claim 14, wherein, in association with the at least one heating conductor, method steps b) and c) are carried out with different machining measures from one another, in order to provide the at least one throughflow opening.

20. The method of claim 12, wherein, in association with the at least one heating conductor, a flow-conducting element is formed in method step c) in association with the at least one throughflow opening.

21. An exhaust gas heating arrangement for an exhaust gas system for an internal combustion engine, the exhaust gas heating arrangement comprising: an exhaust gas conducting housing for conducting a flow of exhaust gas in a main flow direction; a carrier arrangement held in said exhaust gas conducting housing; a first heating conductor mounted on said carrier arrangement; said first heating conductor including: a plurality of heating conductor sections; and, at least one of said plurality of heating conductor sections defining a throughflow opening for passing the exhaust gas therethrough; and, a second heating conductor mounted in said carrier arrangement following said first heating conductor in said main flow direction of said exhaust gas.

22. An exhaust gas system for an internal combustion engine, the exhaust gas system comprising: an exhaust gas heating arrangement including: an exhaust gas conducting housing for conducting a flow of exhaust gas in a main flow direction; a carrier arrangement held in said exhaust gas conducting housing; a first heating conductor mounted on said carrier arrangement; and, said first heating conductor including: a plurality of heating conductor sections; and, at least one of said plurality of heating conductor sections defining a throughflow opening for passing the exhaust gas therethrough; and, a second heating conductor mounted in said carrier arrangement following said first heating conductor in said main flow direction of said exhaust gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention will now be described with reference to the drawings wherein:

[0029] FIG. 1 shows a perspective view of an exhaust gas heater in an exhaust gas conducting housing;

[0030] FIG. 2 shows a partial longitudinal sectional view of the exhaust gas heater inserted into the exhaust gas conducting housing;

[0031] FIG. 3 shows a heating conductor of a heating conductor arrangement of the exhaust gas heater of FIG. 1;

[0032] FIG. 4 shows part of a heating conductor configured according to the disclosure;

[0033] FIG. 5 shows part of a further heating conductor configured according to the disclosure;

[0034] FIG. 6 shows a side view of the heating conductor in FIG. 5 in viewing direction VI in FIG. 5; and,

[0035] FIG. 7 shows a metal flat material blank with heating conductors to be cut out therefrom.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] FIGS. 1 to 3 show an embodiment of an exhaust gas heating arrangement 120 in an exhaust gas system 122 of an internal combustion engine, having an exhaust gas heater 12 which is inserted into, for example, a tubular exhaust gas conducting housing 10, which is elongate at least in sections in the direction of a center axis A of the exhaust gas heater. The exhaust gas heater 12 includes a heating conductor arrangement which is denoted in general by 14 and is carried by a carrier arrangement 16 on the exhaust gas conducting housing 10.

[0037] The carrier arrangement 16 includes two disk-like carrier elements 18, 20 which are formed, for example, from sheet metal material and are structurally identical to each other. The carrier elements 18, 20 are constructed with a central region 22 extending substantially transversely with respect to the center axis A of the exhaust gas heater and with a plurality of carrier arms 24, 26, 28, 30, 32, 34 extending in the direction radially outward from the central region 22. In an outer circumferential region of the carrier elements 18, 20, a fastening region, denoted in general by 38, is formed, with which the carrier elements 18, 20 and therefore the entire exhaust gas heater 12 can be secured on the inner surface of the exhaust gas conducting housing 10, for example by welding. In this fastening region 38, the two carrier elements 18, 20 are curved in the axial direction.

[0038] In the region of each of the carrier arms 24, 26, 28, 30, 32, 34, the fastening region 38 includes a respective fastening section 40, 42, 44, 46, 48, 50.

[0039] Between two fastening sections 40, 42, 44, 46, 48, 50 in each case forming a radially outer end region of a carrier arm 24, 26, 28, 30, 32, 34, in each case one fastening edge 54, 56, 58, 60, 62, 64 connecting the fastening sections of two adjacent carrier arms is formed, and therefore the fastening sections 40, 42, 44, 46, 48, 50, with the fastening edges 54, 56, 58, 60, 62, 64 extending in between and connecting adjacent carrier arms 24, 26, 28, 30, 32, 34 to one another, provide a structure of the fastening region 38 that is substantially continuous in the circumferential direction.

[0040] Via the configuration of the carrier arms 24, 26, 28, 30, 32, 34 and also of the fastening region 38, a targeted flow conduction is achieved for the exhaust gas flowing through the exhaust gas heater 12. In particular, regions which are intended to be protected from a direct flow toward them can be covered by the carrier arms 24, 26, 28, 30, 32, 34. These may, for example, be regions in which sensors are arranged, for example, for detecting the temperature or for detecting the composition of the exhaust gas. Via the substantially annularly continuous fastening region 38, a flow is prevented in the radially outer region directly along a comparatively cold inner surface of an exhaust gas conducting housing 10 containing the exhaust gas heater 12.

[0041] FIG. 3 shows an upstream first heating conductor 66 of two heating conductors 66, 68, that are consecutive in the flow direction, of the heating conductor arrangement 14. Each of the two heating conductors 66, 68 which are basically not sheathed with electrically insulating material is provided by cutting each out from a metal flat material blank, for example by punching or cutting, for example laser cutting or water jet cutting, and has an outer circumferential contour which is adapted to the inner circumferential contour of the exhaust gas conducting housing 10 and, in the illustrated embodiment, is roundedly flattened. Each of the two heating conductors 66, 68 is constructed with a plurality of meandering winding fields 70, 72, 74, 76, 78, 80 following one another in the circumferential direction, wherein, in each of the meandering winding fields 70, 72, 74, 76, 78, 80, meandering winding sections, which provide heating conductor sections 82, 84, 86, 88, 90 staggered substantially radially with respect to one another and which are formed extending approximately in the circumferential direction, are provided. In one of their circumferential end regions, the meandering winding sections or heating conductor sections 84, 86, 88, 90 are each connected to a meandering winding section or heating conductor section 82, 84, 86, 88 positioned further radially outward. In their other circumferential end region, the meandering winding sections or heating conductor sections 82, 84, 86, 88 are each connected to a meandering winding section or heating conductor section 84, 86, 88, 90 lying further radially inward. The respective radially outer meandering winding sections or heating conductor sections 82 of the meandering winding fields 72, 74, 76, 78 connect directly mutually adjacent meandering winding fields to one another. Equally, the radially inner meandering winding sections or heating conductor sections 90 of the meandering winding fields 70, 72, 74, 76, 78, 80 connect directly mutually adjacent meandering winding fields, such that overall a serial electrical circuit of the meandering winding fields 70, 72, 74, 76, 78, 80 is obtained.

[0042] Although producing such heating conductors 66, 68 by cutting them out from a flat material gives rise to the possibility in a particularly simple and economic manner of providing the heating conductors 66, 68 with a comparatively complex structure of the meandering winding sections or heating conductor sections thereof, other production processes, such as, for example, metal injection molding or sintering, are in principle also possible for obtaining such heating conductors 66, 68.

[0043] The radially outer meandering winding sections or heating conductor sections 82 of the meandering winding fields 70, 80 of the first heating conductor 66 respectively provide a first connection region 92 and a second connection region 94 of the upstream first heating conductor 66. Equally, the radially outer meandering winding sections or heating conductor sections of the same meandering winding fields of the second heating conductor 68 provide a first connection region and a second connection region of the second heating conductor 68. With their first connection regions, the heating conductors 66, 68 each provide a voltage source connection region with which the heating conductors can be connected to a voltage source, for example via connection elements 100, 102 penetrating the exhaust gas conducting housing 10 in an electrically insulated and gas-tight manner. With their second connection regions, the two heating conductors 66, 68 provide contact connection regions in which the two heating conductors 66, 68 are interconnected in an electrically conducting manner, for example by a rivet bolt or welding or the like, such that, in this embodiment, an electrical serial circuit of the two heating conductors is produced. In the region of the connection regions, the heating conductors 66, 68 or the respective radially outer meandering winding sections or heating conductor sections 82 have a comparatively large width in order, because of the locally lower electrical resistance in these regions, which are shielded from exhaust gas flowing toward them, to reduce the generation of heat in comparison to the regions to which flow can be freely directed.

[0044] In an alternative configuration, for each of the heating conductors 66, 68, the second connection regions can also provide voltage source connection regions such that, for example, the two first connection regions of the two heating conductors 66, 68 can be connected to the connection element 100 and, via the latter, to a voltage source, while the second connection regions of the two heating conductors 66, 68 can be connected to each other and, via the connection element 102, to the voltage source, thus producing an electrically parallel circuit of the heating conductors 66, 68. In particular when a parallel circuit of the two heating conductors 66, 68 is selected, the heating conductors 66, 68 self-regulate if they are exposed to different exhaust gas temperatures, and locally different electrical resistances of the heating conductors 66, 68 thereby occur.

[0045] By the heating conductors 66, 68 lying one behind another in the direction of the center axis A of the exhaust gas heater and therefore also in a main flow direction of the exhaust gas, a comparatively large surface area for thermal interaction with the exhaust gas to be heated is achieved while the overall size is axially compact. In order to ensure that the second heating conductor 68, which is positioned further downstream, is not positioned completely in the flow shadow of the first heating conductor 66, which is positioned further upstream, the two heating conductors 66, 68 have non-identical structures or profiles of the individual meandering winding sections or heating conductor sections 82, 84, 86, 88. In the individual meandering winding fields 70, 72, 74, 76, 78, 80, the meandering winding sections or heating conductor sections 84, 86, 88 of the two heating conductors 66, 68 are in particular not completely congruent with each another, but rather are offset radially with respect to each another such that the second heating conductor 68, which is positioned further downstream, protrudes, at least in regions transversely with respect to the main flow direction H of the exhaust gas, beyond the first heating conductor 66, which is positioned further upstream. There is therefore virtually no cross-sectional region which is not covered by one of the two heating conductors 66, 68, and therefore, even taking into account the swirling or turbulence occurring as the flow passes through the two heating conductors 66, 68, a highly efficient and uniform heating of the exhaust gas flow is achieved. The radially outer meandering winding sections or heating conductor sections that are surrounded radially in regions by the fastening region 38 can be substantially congruent to one another. The radially inner meandering winding sections of the two heating conductors 66, 68 can also be congruent to one another.

[0046] For the fixed attachment to the carrier arrangement 16 or to the carrier elements 18, 20 thereof, a fixed assembly can be achieved in a plurality of fastening regions 106 by the carrier elements 18, 20 and by fastening bolts 110 passing through the latter and the heating conductors 66, 68 and also through insulating elements 108 positioned between the heating conductors 66, 68.

[0047] It should be pointed out that the basic configuration of an exhaust gas heating arrangement 120 has been described above with respect to FIGS. 1 to 3, in which configuration one or more heating conductors having the construction described below with respect to FIGS. 4 to 6 can be used. The overall structure of such an exhaust gas heating arrangement can differ in a wide variety of configuration aspects from the configuration described above with respect to FIGS. 1 to 3. Just a single heating conductor can be carried by the carrier arrangement on the exhaust gas conducting housing for example, or more than two for example differently configured heating conductors can be carried on or in the exhaust gas conducting housing. The heating conductor sections providing a generally wound structure of a respective heating conductor can also have a structure differing from the, for example, meandering structure having a plurality of meandering winding fields that has been described in detail above. Thus, for example, a plurality of heating conductor sections can be arranged as respective meandering winding sections in a manner extending substantially rectilinearly and running parallel next to one another and in this way can cover the entire flow cross section. Furthermore, heating conductor sections can be provided by winding sections, which surround one another in the manner of a winding, of a spiral structure.

[0048] FIG. 4 shows a portion of a heating conductor, for example the above-described heating conductor 66 of the exhaust gas heating arrangement 120. It should be pointed out that the heating conductor 68 or a possibly single heating conductor of such an exhaust gas heating arrangement could also be formed in an identical or similar way.

[0049] It is seen in FIG. 4, in the two heating conductor sections 82, 84 which are illustrated partially or in sections here and which can likewise form meandering winding sections of the heating conductor 66, that a plurality of throughflow openings 124 arranged following one another in a longitudinal direction H of the heating conductor section are provided in these heating conductor sections 82, 84. Each of the throughflow openings 124 can be elongate in a longitudinal direction D of the throughflow opening, which substantially also corresponds to the locally respectively present longitudinal direction H of the heating conductor section.

[0050] Various advantages are afforded by the provision of such throughflow openings 124. Firstly, the blocking introduced by such a heating conductor in an exhaust gas system is limited or is reduced in comparison to a configuration without such throughflow openings. Secondly, an enlarged surface area, in which heat can be transmitted to the exhaust gas flowing around such a heating conductor 66, is provided by the surface regions, which border the throughflow openings 124, of the construction material of a respective heating conductor section. In comparison to the surface area lost by the formation of the throughflow openings 124 on the front side and/or rear side of the respective heating conductor 82, 84, this additionally obtained heat transmission surface is larger, the smaller the opening cross-sectional area is in comparison to the thickness of the construction material of the heating conductor 66.

[0051] The throughflow openings 124 can be produced, for example, when the heating conductor 66 is produced, for example, from a metal flat material blank 140, illustrated in FIG. 7, by punching. Use can therefore be made of a punching tool which not only punches the contour of the heating conductor 66, but also generates the openings 124. Also when the heating conductor 66 is cut out by cutting, for example laser beam cutting or water jet cutting, the openings 124 can be formed at the same time as the heating conductor 66 is cut out from the metal flat material blank.

[0052] In particular whenever the openings 124 have a particularly slender structure or the webs 134, 136 remaining on either side of same in a respective heating conductor section 82, 84 are comparatively narrow, it may be advantageous to separate the operation of cutting out the heating conductor 66 per se and the operation of producing the throughflow openings 124. For example, on the plate-like metal flat material blank 140, first of all wherever respective heating conductors or heating conductor sections are to be produced later, one throughflow opening 124 or a plurality of throughflow openings 124 can be produced in a machining operation, specifically using a machining measure which is particularly suitable taking into consideration the structure to be produced of a respective throughflow opening 124. For example, this cutting out may take place by laser beam cutting or the like. If the throughflow openings 124 have been produced, then, in a further machining operation, the heating conductor or the heating conductors 66 can subsequently be cut out from the metal flat material blank 140, for example by another machining measure, for example, punching. Finishing operations are then no longer required. Of course, this further machining operation could be carried out using the same machining measure, that is, for example, also by laser beam cutting.

[0053] Alternatively, it could be provided that first of all individual heating conductors 66 are cut out from the metal flat material blank 140 in order then, in a subsequent machining operation, to produce one or more throughflow openings 124 in various heating conductor sections of a heating conductor 66, the basic structure of which has already been cut out from the blank. In each case particularly suitable machining measures can also be used here for the various machining operations for this purpose, which machining measures may differ from one another but basically may also be identical to one another. In principle, it is also possible, taking into consideration the structure of the individual heating conductor sections or of the throughflow openings to be produced, to produce a portion of the throughflow openings before the heating conductors are cut out from the blank, and to produce a further portion of the throughflow openings after the cutting out, and, for the machining operations, to in each case use the optimum machining measures, which may differ from one another, but basically may also be identical.

[0054] It should be pointed out that, in the case of the heating conductor 66 partially illustrated in FIG. 4, at the end regions of the heating conductor section 82 and of the heating conductor section 84 fastening structures 126 are provided, in the region of which the heating conductor 66 or a plurality of such heating conductors consecutively can be fixed on the carrier elements 18, 20 using the insulating elements 108 illustrated in FIG. 2 and the fastening bolts 110. These structures 126 replace the openings 110, which can be seen in FIG. 3 and serve for the same purpose, in regions of the illustrated heating conductor 66 that are assigned to the various fastening regions 106.

[0055] An alternative configuration of a heating conductor 66 constructed according to the disclosure is illustrated in FIG. 5. It is seen here that the throughflow openings 124 which can be seen in the heating conductor section 82 are formed, for example, by the formation of a substantially U-shaped incision 128. The formation of such a U-shaped incision 128 results in a tongue-like flow-conducting element 130 which is elongate in the longitudinal direction H of the heating conductor section or in a respective longitudinal direction D of the throughflow opening and is attached as an integral part to the heating conductor 66 or to the heating conductor section 82. The flow-conducting element 130 can be bent out of the plane E, which can be seen in FIG. 6 and is spanned by the heating conductor 66, for example in a downstream direction, such that a defined influence on the flow conduction in the region of such a heating conductor 66 can be provided by such a tongue-like flow-conducting element 130, which is offset with respect to the heating conductor itself or in regions with respect to the plane E.

[0056] As an alternative to the attachment, which can be seen in FIG. 5, of a respective flow-conducting element to the heating conductor 66 at the associated throughflow opening 124 in the region of a respective longitudinal end region 132, the attachment could also take place along a longitudinal edge of the associated throughflow opening 124 and a respective flow-conducting element 130 could be bent out of the plane E, by bending about a bending line extending substantially parallel to the longitudinal direction D of the throughflow opening, such that it is arranged offset in the direction of the center axis A of the exhaust gas heater in regions with respect to the plane E or with respect to the heating conductor 66, or is arranged inclined with respect to the plane.

[0057] It should be pointed out that such throughflow openings 124 on the heating conductor 66 can be arranged in all heating conductor sections, that is, also those which are not illustrated in FIGS. 4 to 6, for example with the same distribution or at the same distance from one another and consecutively. Alternatively, depending on the flow conditions to be achieved or adapted to the flow conditions present in an exhaust gas system, the density of the throughflow openings 124 in individual heating conductor sections or between individual heating conductor sections can vary. There can also be heating conductor sections in which no throughflow openings are provided. The throughflow openings 124 can also have different cross-sectional geometries, for example a circular cross-sectional geometry, and they can be positioned, for example, at an angle with respect to the longitudinal direction H of the heating conductor section.

[0058] Via the throughflow openings 124 provided in the heating conductor 66, not only is there an influence on the exhaust gas flow, but the current flow through the heating conductor 66 is also affected. In the region of the throughflow openings 124, the current flow is divided between the two webs 134, 136 laterally bounding a respective throughflow opening 124. Depending on the width or the cross-sectional area of the webs 134, 136, the latter may have identical or differing electrical resistances, and therefore, by corresponding dimensioning of the webs 134, 136, the heat generated therein by the respective electrical resistance and thus the energy transmitted to the exhaust gas can also be influenced.

[0059] It should furthermore be pointed out that, of course, such throughflow openings can be used in basically differently structured heating conductors of substantially plate-like construction. For example, such a heating conductor could have a spiral structure, wherein individual heating conductor sections can be defined, for example, by respective winding sections of the spiral structure. Also in the case of a meandering profile of the heating conductor sections, the latter can each be constructed in a manner extending substantially rectilinearly and lying next to one another, wherein, in order to adapt the outer circumferential structure of a heating conductor constructed in such a manner to the cross-sectional geometry of a respective exhaust gas conducting housing, the length of the heating conductor sections extending rectilinearly can vary.

[0060] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.