SEGMENTED ELECTRICAL RUNOUT

Description

Technical area

[0001] The invention relates to a segmented electrical feedthrough for electrically contacting a heating conductor through a housing, comprising a contact section and an insulating section, wherein the insulating section has an electrical conductor, an insulating means, and an outer sleeve, wherein the electrical conductor and the insulating means are arranged within the outer sleeve, and the electrical conductor is electrically insulated from the outer sleeve by the insulating means, wherein the contact section is connected to the electrical conductor at a first end face, and the electrical conductor is connectable to a heating conductor at its second end face opposite the first end face. The invention also relates to a method for producing the electrical feedthrough. State of the art

[0002] Electric heating elements are now routinely used to heat exhaust gases in an exhaust system downstream of a combustion engine or the exhaust gas flowing through an exhaust system. The goal here is to more quickly reach a temperature threshold at which effective conversion of the pollutants carried in the exhaust can occur. This is necessary because the catalytically active surfaces of the catalysts installed in the exhaust system used for exhaust gas aftertreatment only allow sufficient conversion of the respective pollutants above a minimum temperature, the so-called light-off temperature.

[0003] Known solutions in the prior art include so-called heating catalysts, which have a metallic structure connected to a voltage source or a metallically coated ceramic structure which can be heated by utilizing the ohmic resistance.

[0004] To electrically connect the heatable structure, an electrical conductor must be inserted at least once through the housing of the exhaust system or a catalytic converter located in the exhaust system. It must be ensured that the feedthrough is gas-tight, that there is electrical insulation between the housing and the electrical conductor, and that sufficient durability is guaranteed. The electrical conductor is usually made of a solid, solid material, such as a metal bolt.

[0005] DE 10 2012 110 098 B4 discloses a method for producing an electrical feedthrough for the power supply of an electric exhaust gas heater in a motor vehicle. The feedthrough has an outer tube, the interior of which is penetrated by an electrical conductor. The electrical conductor projects beyond the outer tube on at least one end face of the outer tube. The electrical conductor is surrounded by an insulating material in the interior of the outer tube. The feedthrough is produced by cutting a compacted rod material to length, with regions of the section acting as the outer tube and the section acting as the insulating material being removed by machining processes in order to produce an electrical feedthrough of the desired length with a desired projection of the electrical conductor beyond the outer tube.

[0006] A particular disadvantage of the prior art methods for producing electrical feedthroughs is that the compacted bar stock used is very expensive due to its multi-layer structure. Furthermore, a significant portion of approximately two-thirds of the bar stock is destroyed during machining to expose the electrical conductor and cut the electrical feedthrough to length, resulting in unused material being wasted. This makes the manufacturing process particularly complex and costly. Description of the invention, task, solution, advantages

[0007] Therefore, the object of the present invention is to provide a segmented electrical feedthrough and a suitable manufacturing method which allows a simplified and cost-effective production of the electrical feedthrough with at least equally good technical properties.

[0008] The problem with regard to the electrical feedthrough is solved by an electrical feedthrough having the features of claim 1.

[0009] An embodiment of the invention relates to a segmented electrical feedthrough for electrically contacting a heating conductor through a housing, with a contact section and an insulating section, wherein the insulating section has an electrical conductor, an insulating means and an outer sleeve, wherein the electrical conductor and the insulating means are arranged within the outer sleeve and the electrical conductor is electrically insulated from the outer sleeve by the insulating means, wherein the contact section is connected to the electrical conductor on a first end face, and the electrical conductor can be connected to a heating conductor on its second end face opposite the first end face, wherein the contact section and the insulating section are formed from two different elements which are durably connected to one another by means of a joining process.

[0010] The electrical feedthrough is used to route an electrical conductor through the housing of an exhaust pipe or catalytic converter. The feedthrough must withstand the temperatures encountered and be gas-tight to prevent exhaust gas from escaping. The electrical conductor should be electrically insulated from the housing to prevent a short circuit.

[0011] Electrical feedthroughs typically have a connection point to a live wire on the outside of the housing. This connection point is usually formed by a threaded bolt, which is part of the feedthrough's electrical conductor. The live wire is screwed onto the feedthrough's electrical conductor using a suitable connector.

[0012] The contact section is the section at which, on the one hand, the connection to a current-carrying line can be created and, on the other hand, a connection to the electrical conductor of the insulation section can be established.

[0013] For this purpose, the contact section preferably has a conical area with an external thread. The plug of the current-carrying cable can be screwed onto this external thread and permanently secured. The conical design of this area aids the assembly of the plug through its self-centering effect.

[0014] The contact section is connected to the electrical conductor of the insulation area by a durable joining process, in particular by soldering or welding.

[0015] The insulation section itself is formed from a composite material with a cylindrical electrical conductor at its center, surrounded by an insulating material that insulates it from the metallic outer sleeve. In a preferred embodiment, the three different regions have an identical axial extension, allowing the insulation section to be cut from a suitable bar stock at a length suitable for the application. This largely eliminates waste or material loss due to machining.

[0016] The electrical conductor is preferably made of a steel such as 2.4869. The material chosen for the electrical conductor and the contact section can be identical or different; in any case, the oxidation resistance and the specific electrical resistance should be comparable or similar. The insulation is made of an oxide ceramic, for example. The outer sleeve can also be made of a steel material.

[0017] The material of the outer sleeve and the electrical conductor can be identical, but does not have to be.

[0018] In an alternative embodiment, the electrical conductor may protrude slightly, preferably only a few millimeters, on one side in the axial direction beyond the insulation material and / or the outer sleeve. This can be achieved by a machining process, with particular attention being paid to removing as little material from the outer sleeve and the insulation material as possible. Therefore, the projection of the electrical conductor is limited to a few millimeters.

[0019] The overhang of the electrical conductor is preferably located on the side of the insulation section that, when installed, faces the heating conductor located inside. This non-symmetrical design also allows for a clear alignment of the insulation section relative to the contact section, simplifying assembly and preventing assembly errors.

[0020] It is particularly advantageous if the contact section has a conical section and a cylindrical section, wherein the cylindrical section forms the interface to the insulation section.

[0021] The cylindrical section of the contact section is particularly advantageous because the electrical conductor in the insulation section generally also has a cylindrical cross-section. This makes connecting the contact section to the insulation section particularly easy to implement. The cylindrical section is preferably aligned concentrically to the electrical conductor. The cylindrical section can preferably have the same diameter as the electrical conductor. In a particularly preferred alternative embodiment, the cylindrical section can also have a slightly smaller diameter than the electrical conductor, which simplifies assembly and ensures that the cylindrical section does not come into contact with the insulation material and, in particular, does not come into electrically conductive contact with the outer sleeve.

[0022] The conical section can preferably be designed in such a way that screwing on a plug is as easy as possible. Preferably, the conical section and the cylindrical section share a common central axis. In alternative embodiments, however, the conical section could also be angled to the central axis of the cylindrical section, for example.

[0023] It is also advantageous if the insulation section is formed from a composite material, wherein this has an internal electrical conductor which is surrounded in the circumferential direction by a sleeve-like electrical insulation material, wherein the internal electrical conductor and the electrical insulation material are enclosed by a metallic outer sleeve.

[0024] Such a composite material can be manufactured easily and on a large scale. Cutting the composite material to length is achieved using simple cutting processes with minimal material waste. The thickness of the electrical conductor, the insulation layer, and the outer sleeve, as well as the selected materials, can be easily varied.

[0025] A preferred embodiment is characterized in that the insulation section has a first end face and a second end face, wherein the first end face forms the interface to the contact section of the electrical feedthrough and the second end face forms the interface to the heating conductor and / or a connection section.

[0026] The insulation section follows the contact section in the direction of current flow, and the heating conductor to be energized follows the insulation section. The insulation section, or more precisely the electrical conductor within the insulation section, has two end faces, to which the contact section and the heating conductor to be energized can be connected. Since the insulation section is preferably produced from a bar stock, the end faces are preferably parallel to and opposite each other.

[0027] It is also preferable if the bushing has a connection section which is arranged on the second end face of the insulation section and is permanently connected to the electrical conductor of the insulation section.

[0028] An additional connection section is formed in particular by a disc-shaped or cylindrical element which can be applied to the end face of the insulation section facing away from the contact section. The connection section increases the distance between the insulation section and the heating conductor. This is particularly advantageous when the electrical conductor does not protrude beyond the insulation material and the outer sleeve. The element forming the connection section can also have a special shape on the side facing the heating conductor in order to be able to be connected to the heating conductor more easily. For example, a structured surface, a surface set at an angle or a curved surface is conceivable. The surface of the connection section facing away from the insulation section is preferably adapted to the shape of the heating conductor to be contacted.

[0029] Furthermore, it is advantageous if the electrical conductor, the insulation, and the outer sleeve have identical axial extensions and the end regions of the elements are flush with each other. This is particularly advantageous for simple and material-saving production of the insulation section.

[0030] The problem with regard to the method is solved by a method having the features of claim 7.

[0031] An embodiment of the invention relates to a method for producing a segmented electrical feedthrough, wherein the contact section and the insulation section are permanently connected to one another by means of a joining process, wherein the contact section and the insulation section are permanently connected to one another at the first end face of the insulation section.

[0032] A particular advantage of this inventive method is that the insulation section, which is connected to the housing at the outer sleeve through which the electrical conductor is to be routed, can be manufactured particularly easily and with minimal material stress. Since the composite material used is expensive and the otherwise necessary machining steps require long setup times and thus production time, the use of simply constructed and quickly manufactured insulation sections is particularly advantageous.

[0033] To achieve a fully functional electrical feedthrough, it is necessary to create a connection point for the connector and to enable a connection for the heating conductor on the other side of the insulation section. The segmented design, in particular, allows for the cost-effective and simple production of the individual sections of the electrical feedthrough. Using a joining process, such as soldering, the individual sections can be joined together to form a stable and durable electrical feedthrough.

[0034] Soldering, in particular, is an advantageous joining method, since soldering processes in soldering furnaces are already carried out during the production of honeycomb bodies for catalysts, whereby the sections of the electrical feedthrough can be easily connected.

[0035] Furthermore, it is advantageous if the contact section and the insulation section are aligned relative to one another in such a way that the contact section is in electrically conductive contact only with the electrical conductor of the insulation region. Particularly preferably, the electrical conductor and the contact section are aligned concentrically with one another.

[0036] Furthermore, it is expedient if the contact section and the insulation section are fixed to each other by means of a fixing agent before the joining process for producing the permanent connection is carried out.

[0037] A fixing means can, for example, be a sleeve into which the elements are inserted to achieve a predetermined positioning relative to one another. Such a sleeve, which can also be referred to as a mold, can be made of graphite or a ceramic, for example, or a ceramic-coated metal. The sleeve is preferably constructed in such a way that it can withstand a soldering process without damage and allows for easy removal of the elements after the soldering process.

[0038] Alternatively, the individual elements can have threads, alternating internal and external threads, so that they can be soldered at the contact points and screwed together.

[0039] Alternatively, the elements can have holes into which adapters are inserted, allowing the elements to be precisely positioned relative to each other. The adapters remain in the holes after the soldering process and thus become part of the electrical conductor.

[0040] Another alternative is to precisely press the elements together. Here, too, a solder is applied to the contact surfaces between the elements, which creates the connection between the elements during the subsequent soldering process.

[0041] In particular, the contact surfaces between the elements, especially the electrical conductor and the contact section and the electrical conductor and the connection section, if provided, can be reworked in such a way that, in addition to the integral connection created during soldering, a positive connection is also achieved. For this purpose, tenon joints, structured surfaces, interlocking elements, or projections and shoulders can be provided to create a positive connection.

[0042] It is also advantageous if the contact section is inserted into a precisely fitting mold with the conical region facing downwards, wherein the interface arranged on the cylindrical region is first coated with a solder before the insulation section is placed onto the contact section with the first end face in such a way that the contact section is only in conductive contact with the electrical conductor, wherein the mold with the inserted parts and the solder layer is then subjected to a soldering process.

[0043] The brazing process is preferably carried out in a brazing furnace, which is also used for brazing the metallic honeycomb structures of the catalysts. This creates process economy, as the brazing processes can take place in parallel.

[0044] The mold is successively loaded with the elements that form the electrical feedthrough, with solder being applied to the planned contact surfaces between the elements. The elements, fixed in the mold and appropriately soldered, are finally heated to the required temperature in a suitable furnace, so that the solder melts and a permanent connection is created.

[0045] The electrical conductor and the solder used are preferably nickel-based. In particular, the bolt forming the electrical conductor is preferably made predominantly of nickel.

[0046] Furthermore, it is preferable if the terminal section is placed on the second end face of the insulation section after the second end face has been coated with a solder and before the mold with the inserted parts is subjected to the soldering process.

[0047] Depending on the design of the insulation section, especially the electrical conductor, the provision of a terminal section is necessary to create sufficient distance between the heating conductor and the outer sleeve to prevent electrical short circuits. The contact point between the electrical conductor and the terminal section is accordingly also soldered before the entire assembly is subjected to the soldering process.

[0048] Advantageous further developments of the present invention are described in the subclaims and in the following description of the figures. Short description of the drawings

[0049] The invention is explained in detail below using exemplary embodiments with reference to the drawings. In the drawings: Fig. 1 is a sectional view through a segmented electrical feedthrough, wherein the electrical conductor projects beyond the insulation material and the outer sleeve on one side in the axial direction, Fig. 2 is a sectional view through an alternatively designed segmented electrical feedthrough, wherein the electrical conductor has the same axial extent as the insulation material and the outer sleeve, wherein a connection section is connected to the electrical conductor, which serves as a connection point to the heating conductor (not shown), Fig. 3 is a sectional view through an alternatively designed segmented electrical feedthrough, wherein a positive connection is additionally provided between the insulation section and the contact section, and Fig. 4 is a sectional view through a further alternatively designed segmented electrical feedthrough, wherein a different connection is provided between the insulation section and the contact section. Preferred embodiment of the invention

[0050] The Figure 1 shows a segmented electrical feedthrough 1. The feedthrough 1 is formed from a contact section 2 and an insulation section 3. The contact section 2 has a conical section 4, which can carry an external thread in order to screw a corresponding plug (not shown) onto the contact section 2. Furthermore, the contact section 2 has a cylindrical section 5, which adjoins the conical section 4 and forms the contact point to the electrical conductor 6 of the insulation section 3.

[0051] The contact section is preferably made of a material with good electrical conductivity, characterized by high oxidation resistance and low electrical resistivity. A preferred material, for example, is steel 2.4869.

[0052] The contact section 2 is followed by the insulation section 3. As shown in the Figure 1 As can be seen, the insulation section 3 is formed from the electrical conductor 6, the insulation material 7 and the outer sleeve 8. The electrical conductor 6 preferably has a slightly larger diameter than the cylindrical section 5. In Figure 1 In the example shown, the cylindrical section has a diameter of 7.5 millimeters, while the electrical conductor 6 has a diameter of 8 millimeters. These dimensions are exemplary but give an impression of the preferred proportions.

[0053] The electrical conductor 6 has in the embodiment of the Figure 1 a longer axial extension than the insulation material 7 and the outer sleeve 8. This results in a projection of the electrical conductor 6, which simplifies the connection of the heating conductor (not shown).

[0054] The projection of the electrical conductor 6 can be achieved, for example, by machining the outer sleeve 8 and the insulation material 7.

[0055] In Figure 1 Form 9 is also shown, which is used to correctly position the individual elements of the segmented electrical feedthrough prior to soldering. Form 9 has recesses adapted to the individual elements, which ensure the elements are precisely positioned relative to one another.

[0056] The Figure 2 shows an alternative embodiment of a segmented electrical feedthrough 10. Elements which are used for Figure 1 are identical, have the same reference numerals.

[0057] In contrast to Figure 1The electrical feedthrough 10 additionally has a connection section 11, which is connected to the electrical conductor 12 at the end face facing away from the contact section. The electrical conductor 12 is in the embodiment of the Figure 2 does not extend beyond the insulation material 7 and the outer sleeve 8. To ensure sufficient spacing of the heating conductor (not shown) from the outer sleeve 8, the cylindrically shaped connection section 11 is connected to the electrical conductor 12. This is also done by soldering the contact point and subsequent soldering. The connection section 11, like the contact section 3, also has a smaller diameter than the electrical conductor 12.

[0058] The shape 13 is extended in such a way that the connection section 11 is also clearly positioned relative to the other elements and fixed for the soldering process.

[0059] Figure 3shows an alternatively designed segmented electrical feedthrough 14. The outer sleeve 8 and the insulation material 7 are as in Figure 1 The contact section 15 has a recess 18 in the cylindrical section 16, which forms the interface with the electrical conductor 17. The recess 18 is arranged centrally. The electrical conductor 17 has a pin 19 corresponding to the recess 18. During assembly, the pin 19 is inserted into the recess 18, thereby forming a positive connection and thus preventing at least relative movements in the radial direction.

[0060] If the pin 19 forms a press fit or an overfit to the recess 18, a fixation in the axial direction can also be created if the two elements are pressed together, i.e. the pin 19 is pressed into the recess 18.

[0061] The Figure 4shows an alternative design of the connection between the electrical conductor 20 and the cylindrical portion 22 of the contact section. Here, the electrical conductor 20 has a plurality of pins 21 or a fully or partially circumferential edge on its outer radial circumference. The cylindrical portion can be inserted into the receptacle thus formed on the electrical conductor 20, thereby ensuring at least radial fixation or, if a press fit is present, additional axial fixation.

[0062] The different features of the individual embodiments can also be combined with each other.

[0063] The examples of the Figures 1 and 4 In particular, they are not restrictive and serve to clarify the inventive concept.

Claims

1. Segmented electrical feedthrough (1, 10, 14) for electrically contacting a heater conductor through a housing, having a contact portion (2, 15) and an insulation portion (3), wherein the insulation portion (3) has an electrical conductor (6, 12, 17, 20), an insulation means (7) and an outer sleeve (8), wherein the electrical conductor (6, 12, 17, 20) and the insulation means (7) are arranged within the outer sleeve (8) and the electrical conductor (6, 12, 17, 20) is electrically insulated in relation to the outer sleeve (8) by the insulation means (7), wherein the contact portion (2, 15) is attached to the electrical conductor (6, 12, 17, 20) on a first end side, and the electrical conductor (6, 12, 17, 20) on the second end side thereof opposite the first end side is connectable to a heater conductor, characterized in that the contact portion (2, 15) and the insulation portion (3) are formed from two different elements which are durably connected to one another by means of a joining method.

2. Segmented electrical feedthrough (1, 10, 14) according to Claim 1, characterized in that the contact portion (2, 15) has a conical portion (4) and a cylindrical portion (5, 16, 22), wherein the cylindrical portion (5, 16, 22) forms the interface to the insulation portion (3).

3. Segmented electrical feedthrough (1, 10, 14) according to one of the preceding claims, characterized in that the insulation portion (3) is formed from a composite material, wherein the latter has an internal electrical conductor (6, 12, 17, 20) which is surrounded in the circumferential direction by an electrical insulation material (7) arranged in the manner of a sleeve, wherein the internal electrical conductor (6, 12, 17, 20) and the electrical insulation material (7) are surrounded by a metallic outer sleeve (8).

4. Segmented electrical feedthrough (1, 10, 14) according to one of the preceding claims, characterized in that the insulation portion (3) has a first end side and a second end side, wherein the first end side forms the interface to the contact portion (2) of the electrical feedthrough (1, 10, 14) and the second end side forms the interface to the heater conductor and / or a connection portion (11).

5. Segmented electrical feedthrough (10) according to one of the preceding claims, characterized in that the feedthrough (10) has a connection portion (11) which is arranged on the second end side of the insulation portion (3) and is durably connected to the electrical conductor (12) of the insulation portion (3).

6. Segmented electrical feedthrough (1) according to one of the preceding claims, characterized in that the electrical conductor (6), the insulation means (7) and the outer sleeve (8) have identical axial extents and the end regions of the elements terminate flush with one other.

7. Method for producing a segmented electrical feedthrough (1, 10, 14) according to one of the preceding claims, wherein the contact portion (2, 15) and the insulation portion (3) are durably connected to one another by means of a joining method, characterized in that the contact portion (2, 15) and the insulation portion (3) are durably connected to one another on the first end side of the insulation portion (3).

8. Method according to Claim 7, characterized in that the contact portion (2, 15) and the insulation portion (3) are aligned with one another in such a way that the contact portion (2, 15) is in electrically conductive contact only with the electrical conductor (6, 12, 17, 20) of the insulation portion (3).

9. Method according to one of the preceding Claims 7 or 8, characterized in that the contact portion (2, 15) and the insulation portion (3) are mutually fixed by means of a fixing means (9, 13, 18, 19, 21) before the joining method for generating the durable connection is carried out.

10. Method according to one of the preceding Claims 7 to 9, characterized in that the contact portion (2, 15) with the conical region (4) facing downward is inserted into an accurately fitting mold (9, 13), wherein the interface arranged on the cylindrical region (5, 16, 22) is first coated with a solder before the insulation portion (3) by way of the first end side is placed on the contact portion (2, 15) in such a manner that the contact portion (2, 15) is in conductive contact only with the electrical conductor (6, 12, 17, 20), wherein the mold (9, 13) with the inserted parts and the solder layer is subsequently subjected to a soldering procedure.

11. Method according to Claim 10, characterized in that the connection portion (11) is placed on the second end side of the insulation portion (3) once the second end side has been coated with a solder and before the mold (13) with the inserted parts is subjected to the soldering procedure.