Abgasheizer

Abstract

Exhaust gas heater (16) for an exhaust system of an internal combustion engine, comprising at least one heating conductor (18) supported on a support structure (24) with heating conductor connection sections (40) and, in association with each heating conductor connection section (40) of the at least one heating conductor (18), a connection unit (22), characterized in that at least one heating conductor connection section (40) is electrically connected to the associated connection unit (22) by means of a flexible connecting element (54).

Description

[0001] The present invention relates to an exhaust gas heater for an exhaust system of an internal combustion engine.

[0002] To supply heat to the exhaust gas or other gas flowing in the exhaust system of an internal combustion engine, thereby accelerating the heating of an exhaust aftertreatment unit located in the exhaust system, such as a catalytic converter or particulate filter, particularly during the start-up phase of an internal combustion engine's operation, and thus bringing the exhaust aftertreatment unit up to operating temperature more quickly, it is known to use exhaust gas heaters that generate heat through electrical excitation. The heat can be absorbed by the exhaust gas flowing through such an exhaust gas heater and carried to a downstream exhaust aftertreatment unit. To electrically excite such exhaust gas heaters, it is necessary to apply the electrical voltage provided in an on-board electrical system, via connection units, through an exhaust system component containing an exhaust gas heater and carrying the exhaust gas, to a heating conductor of the exhaust gas heater, with electrical insulation.

[0003] The object of the present invention is to provide an exhaust gas heater for an exhaust system of an internal combustion engine, in which at least one heating conductor is electrically connected to one or more connection units without the risk of thermomechanically induced fatigue.

[0004] According to the invention, this problem is solved by an exhaust gas heater for an exhaust system of an internal combustion engine, comprising at least one heating conductor supported on a support structure with heating conductor connection sections and, in association with each heating conductor connection section of the at least one heating conductor, a connection unit, wherein at least one heating conductor connection section is electrically connected to the associated connection unit by means of a flexible connecting element.

[0005] By using a flexible connecting element to create an electrically conductive connection between at least one heating conductor connection section and the associated connection unit, a substantially rigid or direct coupling between the heating conductor and such a connection unit, generated, for example, by welding such a heating conductor connection section to the associated connection unit, is avoided, wherein the connection unit and the heating conductor itself, with its heating conductor connection section made of metal material, for example, by cutting it out of a plate-like metal blank, are designed as substantially rigid, i.e., inflexible, assemblies in the sense of the present invention.The electrically conductive connection achieved using a flexible connecting element allows for relative movement between a heating conductor connection section and the associated connection unit. This movement can be caused, for example, by thermally induced changes in length or by vibrations generated by an internal combustion engine during operation. Fatigue fractures in the area of ​​the electrically conductive connection between a heating conductor and a connection unit can thus be largely prevented. Furthermore, the use of such a flexible connecting element enables tolerance compensation between the various components of the exhaust gas heater or an exhaust system containing such a heater in virtually all spatial directions.

[0006] In order to make the most extensive use of the advantages of the exhaust gas heater design according to the invention, it is proposed that the at least one heating conductor has two heating conductor connection sections, wherein each of the two heating conductor connection sections is electrically connected to the connection unit assigned to it by a flexible connecting element.

[0007] The flexible connecting element can comprise a plate-like connection section, a plate-like connection unit, and a flexible connecting element connecting section that connects the plate-like connection section and the plate-like connection unit, and thus has a fundamentally essentially band-like structure, in which only the two areas directly intended for connection to a heating conductor connection section or a connection unit, i.e., the connection section-connection section and the connection unit-connection section, are essentially rigid in their plate-like structure to enable a defined connection.

[0008] It may be provided, for example, that the plate-like connection section is connected to the heating conductor connection section by material bonding, preferably welding or soldering, and / or that the plate-like connection unit connection section is connected to the connection unit by material bonding, preferably welding or soldering.

[0009] For a design that is resistant to exhaust gases and stable and durable under the thermal and mechanical stresses that occur, the flexible connecting element can be constructed at least partially with wire material, preferably wire mesh or wire fabric.

[0010] In particular, in the aforementioned structure of such a flexible connecting element, which is divided into three sections, the flexible connecting element connection section can be constructed with wire material.

[0011] In order to largely exclude any impairment of the heating function of the at least one heating conductor as well as any local flow obstruction in the area of ​​such a flexible connecting element, it is proposed that the at least one heating conductor has a heating area extending substantially in a heating area plane orthogonal to an exhaust gas heater longitudinal axis, and that at least one heating conductor connection section, preferably each heating conductor connection section, extends at an angle with respect to the heating area plane.

[0012] To achieve a design that minimizes disruption to the exhaust gas flow, at least one heating conductor connection section, preferably each heating conductor connection section, can extend, for example, from the heating zone plane essentially in the direction of the exhaust gas heater's longitudinal axis. This makes it possible to position the flexible connecting element(s) with their narrow side perpendicular to the exhaust gas flow.

[0013] The support structure can, for example, comprise a substantially disc-shaped support element on the downstream side of the at least one heating conductor. At least one heating conductor connection section, preferably each heating conductor connection section, can, for example, be arranged extending upstream from the disc-shaped support element, so that the risk of mutual contact between such a heating conductor connection section and the disc-shaped support element, which may be constructed of sheet metal, for example, is eliminated.

[0014] For connection with a flexible connecting element, at least one connection unit, preferably each connection unit, can comprise a connection unit connection section electrically connected to a flexible connecting element.

[0015] At least one connection unit, preferably each connection unit, can comprise a pin-like feedthrough element for electrically insulated passage through a wall of an exhaust gas routing component, wherein the connection unit connection section is arranged at a heating conductor connection end of the feedthrough element.

[0016] For a simple design, the connection unit connection section can be angled and can be fixed in a first angle leg at the connection end of the feedthrough element preferably by material interlocking and in a second angle leg connected to the flexible connecting element.

[0017] Starting from the first angle leg, the second angle leg can extend essentially in the direction of the exhaust gas heater's longitudinal axis, so that mutual contact between the connection unit connection section and the support structure, which could lead to unwanted contact, is also excluded.

[0018] The invention further relates to an exhaust system for an internal combustion engine, comprising an exhaust system component through which exhaust gas flows and at least one exhaust gas treatment unit arranged in the exhaust system component, wherein at least one exhaust gas heater constructed according to the invention is arranged upstream of the at least one exhaust gas treatment unit.

[0019] The invention further relates to a method for manufacturing an exhaust system constructed according to the invention, in which method: - before integrating the at least one heating conductor into the exhaust system component, at least one flexible connecting element, preferably each flexible connecting element, is electrically connected to the heating conductor connection section, and after integrating the at least one heating conductor into the exhaust system component, is electrically connected to the associated connection unit arranged on the exhaust system component. or - before integrating the at least one heating conductor into the exhaust system component, at least one flexible connecting element, preferably each flexible connecting element, is electrically connected to the connection unit arranged on the exhaust system component and is electrically connected to the associated heating conductor connection section after integrating the at least one heating conductor into the exhaust system component.

[0020] This approach ensures that some of the work steps for the electrically conductive connection of a flexible connecting element can be carried out before integrating a heating conductor of an exhaust gas heater into the exhaust system component, i.e., in a state in which such an area for connecting a flexible connecting element is more easily accessible than in a state in which the heating conductor is already installed in the exhaust system component.

[0021] The present invention is described in detail below with reference to the accompanying figures. These show: Fig. 1. A perspective view of an exhaust gas heater for an exhaust system of an internal combustion engine; Fig. 2 the upper area of ​​the exhaust gas heater having two connection units Fig. 1 enlarged; Fig. 3 a flexible connecting element of the exhaust gas heater of the Fig. 1; Fig. 4 A basic representation of an exhaust system of an internal combustion engine.

[0022] Before referring to the Fig. 1 to Fig. 3. The construction of an exhaust gas heater for an exhaust system is described in detail, with reference to the Fig. 4. The basic structure of such an exhaust system for an internal combustion engine, for example on a vehicle, is described.

[0023] The exhaust system 10 comprises an exhaust system component 12, for example, a pipe-like or housing-like structure, in which the exhaust gas A emitted by an internal combustion engine flows. An exhaust gas treatment unit, generally designated 14, is provided in the exhaust system 12. This unit may be, for example, a catalyst (such as an oxidation catalyst or SCR catalyst), a particulate filter, or the like. An exhaust gas heater 16 is arranged upstream of the exhaust gas treatment unit 14. The exhaust gas heater 16 comprises a heating conductor 18 with a heating zone 20 extending substantially in a heating zone plane E orthogonal to a longitudinal axis L of the exhaust gas heater. The exhaust gas A flows through this heating zone. The exhaust gas A absorbs heat and transports it to the downstream exhaust gas treatment unit 14. This is particularly important during operating phases in which the exhaust gas A emitted by the internal combustion engine is still relatively cold.Since the exhaust gas treatment unit 14 has not yet reached its operating temperature to carry out a catalytic reaction, this ensures faster heating of the exhaust gas treatment unit 14.

[0024] To apply the electrical voltage used to heat the heating element of the exhaust gas heater 16, a connection unit, generally designated 22, is used for connection to each pole of an on-board electrical system. A supply line of the on-board electrical system can be connected to each connection unit 22 in order to heat the exhaust gas A or any other gas conveyed through the exhaust system component 12 by applying an electrical voltage to the exhaust gas heater 16 and the resulting current flow in the exhaust gas heater 16.

[0025] The Fig. Figure 1 shows a perspective view of the section of the exhaust system 10 in which the exhaust gas heater 16 is arranged. The exhaust gas heater 16 comprises a support structure, generally designated 24, on which the heating conductor 18 is supported. In the illustrated embodiment, the support structure 24 comprises a disc-shaped, perforated support element 26, which is supported in its radially outer region, for example, on a wall 28 of the pipe-like exhaust system component 12 and is generally arranged on a downstream side of the heating conductor 18. The heating conductor 18, formed, for example, by cutting it out of the plate-like metal blank, is arranged, in particular with its heating area 20, such that its broad sides are oriented upstream and downstream in the exhaust system 10, respectively, with respect to the exhaust gas flow. It should be noted that the support structure 24 is ring-shaped oressentially comprising a cylindrical wall element on which the disc-like support element 26 is supported in its outer circumferential area and which can then be inserted, for example, into the pipe-like exhaust system component 12.

[0026] In the illustrated embodiment, the heating conductor 18 is formed, for example, by cutting it from a plate-like metal blank and has a structure with two adjacent meander coil fields 30, 32. In each meander coil field 30, 32, meander sections 34 of the heating area 20 of the heating conductor 18 extend substantially parallel to each other and substantially orthogonal to the exhaust gas heater longitudinal axis L. In their respective longitudinal end regions, the meander sections 34 are connected to each other by connecting sections 36. In one of the end regions of the meander structure of each meander coil field 30, 32, the last meander sections 34' of the two meander coil fields 30, 32 are connected to each other by a bridge section 38. In the other end areas of the respective meander structures of the meander coil fields 30, 32, heating conductor connection sections 40 connect to the meander sections 34" running there.

[0027] The heating conductor connection sections 40 of the two meander coil fields 30, 32 are angled with respect to the meander sections 34' to which they connect, and also with respect to the other meander sections 34, 34" of the two meander coil fields 30, 32, and thus extend out of the heating area plane E, in which the meander sections 34, 34', 34" and also the bridge section 38 extend, for example at an angle of approximately 90°, so that they extend essentially parallel to the exhaust gas heater longitudinal axis L in the direction upstream, i.e. away from the disk-like support element 26.

[0028] It should be noted that, depending on the shape of the support element 26, the heating zone 20 of the heating conductor 18 could also extend in the direction of exhaust gas flow A, for example, with a conical structure in which the radially inner region of the heating zone 20 is offset relative to the radially outer region of the heating zone 20 in either the upstream or downstream direction. Furthermore, it should be noted that the heating zone 20 could also have a different structure or configuration. In principle, it could also have a structure with more than two successive meandering coils in the circumferential direction, and the coil sections of the meandering coils could also extend essentially circumferentially and be radially staggered relative to one another. A spiral-like structure of the heating zone 20 is also possible.

[0029] Between the two heating conductor connection sections 40 of the two meandering coil fields 30, 32, which are arranged at a circumferential distance from each other with respect to the longitudinal axis L of the exhaust gas heater and essentially in the same axial area, lie the two connection units 22 provided for connection to a voltage source, for example, an on-board electrical system or a battery in a vehicle. These can be essentially identical in construction and each comprises an electrically insulated, pin-like feedthrough element 42 that passes through the wall 28. At its supply line connection end 44, which extends outside the wall 28, each feedthrough element 42 can be electrically connected to such a supply line and thus to the associated pole of a voltage source, for example, by screwing on a contact shoe of a supply line.At its heating conductor connection end 46, which extends within the interior of the exhaust system component 12 enclosed by the wall 28 and through which the exhaust gas A flows, each pin-like feedthrough element 42 is connected, for example, by soldering or welding, to an L-shaped or angled connection unit connection section 48. A first angle leg 50, extending substantially parallel to the direction of extension of a respective feedthrough element 42, can be connected to the respective heating conductor connection end 46. A second angle leg 52, angled at an angle of, for example, 90° with respect to the first angle leg, is arranged such that it extends circumferentially alongside or at a distance from a respective associated heating conductor connection section 40, substantially parallel to the longitudinal axis L of the exhaust gas heater, away from the disc-shaped support element 26.

[0030] In each pair consisting of a heating conductor connection section 40 and the associated connection unit connection section 48, the heating conductor connection section 40 and the second angled leg 52 of the connection unit connection section 48 extend essentially parallel to each other at approximately the same radial level, but not necessarily at exactly the same radial level. The heating conductor connection section 40 and the second angled leg 52 of the connection unit connection section 48 do not directly touch each other.

[0031] The electrical contact between each heating conductor connection section 40 and the associated connection unit 22 is made via a [connection / connection] in the Fig. 2 and Fig. 3. A more detailed illustration of a fundamentally flexible connecting element 54. Each such flexible connecting element 54 comprises a plate-like, inherently rigid connection section 56 and a connection unit 58, also essentially plate-like and inherently rigid. A flexible connecting element 60 extends between the connection section 56 and the connection unit 58. This is, for example, in the configuration of a Fig.The metal wire material 62, formed in the 3 indicatively depicted mesh, woven or knitted fabric, is provided and is therefore flexible, i.e. easily deformable. Other electrically conductive fiber material, such as carbon fibers or the like, can also be used to construct the fundamentally flexible connecting element 54 or the connecting element-connecting section 60 thereof.

[0032] The connection section 56 and the connection unit 58 can therefore be arranged in any spatial position relative to each other. That is, they can be moved away from or towards each other, naturally limited by the length of the connecting element 60, rotated or tilted relative to each other in any spatial direction, and in any such position can be firmly connected to a respective heating conductor connection section 40 or a connection unit 48 or its second angled leg 52, for example by welding or soldering. Alternatively, a rivet or screw bolt passing through a connection section 56 or a connection unit 58 and the associated heating conductor 40 could be used for a fixed, electrically conductive connection.

[0033] It should be noted that the connecting section 56 and / or the connecting unit 58 can be provided, for example, by relatively thin sheet metal, which is arranged around one end of the connecting element 60 and firmly connected to it, for example, by crimping. Openings can then be created that extend through both the sheet metal of the respective connecting section 56 or connecting unit 58 and the end of the connecting element 60 that is surrounded by it. The firm connection of the connecting section 56 or connecting unit 58 to the connecting element 60 can also be supported by passing, for example, a rivet or a screw bolt through such an opening.In the case of a material-bonded connection of the connecting element 54 with the respective associated heating conductor connection section 40 or the associated connection unit 22, the firm connection of the connecting element-connection section 60 with the connection section-connection section 56 or connection unit-connection section 58 provided at the ends of the same can be reinforced by using such openings with welded or soldered connections formed therein.

[0034] By using such a flexible connecting element 54, a direct rigid contact, for example, created by a material bond, between a respective, essentially rigid connection unit 22 and the heating conductor 18, which is also fundamentally a rigid component, is avoided. The heating conductor 18, particularly with its heating conductor connection sections 40, can thus perform thermally or mechanically induced movements with respect to the respective associated feedthrough element 42 without causing excessive stress on the heating conductor 18 on the one hand and the respective connection unit 22 on the other. Furthermore, manufacturing tolerances, for example, in the production of the heating conductor 18 or in the positioning of the connection units 22 on the wall 28 of the exhaust system component 12, do not impair the possibility of establishing an electrical connection between them.

[0035] After integrating the heating conductor 18, which is already supported on the disc-like carrier element 26, into the interior of the exhaust system component 12 surrounded by the wall 28, such that the heating conductor connection sections 40 are each located in the area of ​​the associated connection unit 22, for example accommodating them circumferentially, the two flexible connection elements 54 can be connected to the respective associated heating conductor connection section 40 and / or the respective associated connection unit connection section 48 in the manner described above.For example, it can be provided that, before the heating conductor 18 is integrated into the interior of the exhaust system component 12 surrounded by the wall 28, the flexible connecting elements 54 are already connected to the heating conductor 18 and, after the heating conductor 18 is integrated, are connected to their respective connection units 22 with their connection unit sections 58. Alternatively, the two flexible connecting elements 54 could, before the heating conductor 18 is integrated into the interior of the exhaust system component 12 surrounded by the wall 28, already be connected to the respective connection units 22, for example by a material connection, and, after the heating conductor 18 is integrated into the interior of the exhaust system component 12 surrounded by the wall 28, be connected to their respective connection section 40 of the heating conductor 18 with their connection section sections 56.

Claims

[1] Exhaust gas heater for an exhaust system of an internal combustion engine, comprising at least one heating conductor (18) supported on a support structure (24) with heating conductor connection sections (40) and, in association with each heating conductor connection section (40) of the at least one heating conductor (18), a connection unit (22), wherein at least one heating conductor connection section (40) is electrically connected to the associated connection unit (22) by means of a flexible connecting element (54). [2] Exhaust gas heater according to claim 1, characterized by , that the at least one heating conductor (18) has two heating conductor connection sections (40), wherein each of the two heating conductor connection sections (40) is electrically connected to the connection unit (22) associated with it by a flexible connecting element (54). [3] Exhaust gas heater according to claim 1 or 2, characterized by, that the flexible connecting element (54) comprises a plate-like connection section (56), a plate-like connection unit connection section (58) and a flexible connecting element connection section (60) connecting the plate-like connection section (56) and the plate-like connection unit connection section (58). [4] Exhaust gas heater according to claim 3, characterized by , that the plate-like connection section (56) is connected to the heating conductor connection section (40) by material connection, preferably by welding or soldering, and / or that the plate-like connection unit connection section (58) is connected to the connection unit (22) by material connection, preferably by welding or soldering. [5] Exhaust gas heater according to one of claims 1-4, characterized by, that the flexible connecting element(54) is at least partially constructed with wire material (62), preferably wire mesh or wire fabric. [6] Exhaust gas heater according to claim 5, insofar as it refers back to claim 3, characterized by , that the flexible connecting element connecting section (60) is constructed with wire material (62). [7] Exhaust gas heater according to one of claims 1-4, characterized by , that the at least one heating conductor (18) has a heating area (20) extending substantially in a heating area plane (E) orthogonal to an exhaust gas heater longitudinal axis (L), and that at least one heating conductor connection section (40), preferably each heating conductor connection section (40), extends at an angle with respect to the heating area plane (E). [8] Exhaust gas heater according to one of claims 1-7, characterized by, that at least one heating conductor connection section (40), preferably each heating conductor connection section (40), extends substantially in the direction of an exhaust gas heater longitudinal axis (L). [9] Exhaust gas heater according to one of claims 1-8, characterized by , that the support structure (24) on one side of the at least one heating conductor (18) comprises a substantially disk-shaped support element (26), and that at least one heating conductor connection section (40), preferably each heating conductor connection section (40), extends in the direction away from the disk-shaped support element (26). [10] Exhaust gas heater according to one of claims 1-9, characterized by , that at least one connection unit (22), preferably each connection unit (22), comprises a connection unit connection section (48) electrically connected to a flexible connecting element (54). [11] Exhaust gas heater according to claim 10, characterized by, that at least one connection unit (22), preferably each connection unit (22), comprises a pin-like feedthrough element (42) for electrically insulated passage through a wall (28) of an exhaust gas routing component (12), wherein the connection unit connection section (48) is arranged at a heating conductor connection end (46) of the feedthrough element (42). [12] Exhaust gas heater according to claim 11, characterized by , that the connection unit connection section (48) is angled and is preferably fixed by material interlock in a first angle leg (50) at the heating conductor connection end (46) of the feedthrough element (42) and is connected to the flexible connecting element (54) in a second angle leg (52). [13] Exhaust gas heater according to claim 12 and claim 8, characterized by , that the second angle leg (52) extends, starting from the first angle leg (50), essentially in the direction of the exhaust gas heater longitudinal axis (L). [14] Exhaust system for an internal combustion engine, comprising an exhaust system component (12) through which exhaust gas (A) flows and at least one exhaust gas treatment unit (14) arranged in the exhaust system component (12), wherein at least one exhaust gas heater (16) according to one of claims 1-13 is arranged upstream of the at least one exhaust gas treatment unit (14). [15] Method for manufacturing an exhaust system according to claim 14, wherein the method: - before integrating the at least one heating conductor (18) into the exhaust system component (12), at least one flexible connecting element (54), preferably each flexible connecting element (54), is electrically connected to the heating conductor connection section (40), and after integrating the at least one heating conductor (18) into the exhaust system component (12), is electrically connected to the associated connection unit (22) arranged on the exhaust system component (12), or - before integrating the at least one heating conductor (18) into the exhaust system component (12), at least one flexible connecting element (54), preferably each flexible connecting element (54), is electrically connected to the connection unit (22) arranged on the exhaust system component (12) and is electrically connected to the associated heating conductor connection section (40) after integrating the at least one heating conductor (18) into the exhaust system component (12).

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