Segmented Electrical Feedthroughs

Abstract

Segmented Electrical Feedthrough. The present invention relates to a segmented electrical feedthrough (1, 10, 14) for electrically contacting a heating conductor through a housing, the segmented electrical feedthrough (1, 10, 14) comprising a contact portion (2, 15) and an insulating portion (3), the insulating portion (3) having an electrical conductor (6, 12, 17, 20), an insulating means (7) and an outer sleeve (8), the electrical conductor (6, 12, 17, 20) and the insulating means (7) being disposed within the outer sleeve (8), the electrical conductor (6, 12, 17, 20) being The present invention relates to an electrical feedthrough, which is electrically insulated from the outer sleeve (8) by insulating means (7), and which has a contact portion (2, 15) coupled to the electrical conductor (6, 12, 17, 20) at a first end face thereof, the electrical conductor (6, 12, 17, 20) being connectable to a heating conductor at a second end face thereof opposite the first end face, the contact portion (2, 15) and the insulating portion (3) being formed from two distinct elements which are rigidly connected to each other by means of a joining process. The present invention further relates to a method for manufacturing a segmented electrical feedthrough.

Description

[Technical Field]

[0001] The present invention relates to a segmented electrical feedthrough for electrically contacting a heating conductor through a housing, the electrical feedthrough comprising a contact portion and an insulating portion, the insulating portion having an electrical conductor, insulating means, and an outer sleeve, the electrical conductor and insulating means being disposed within the outer sleeve, the electrical conductor being electrically insulated from the outer sleeve by the insulating means, the contact portion being coupled to the electrical conductor at a first end surface, and the electrical conductor being connectable to the heating conductor at a second end surface opposite the first end surface. The present invention also relates to a method of manufacturing the electrical feedthrough. [Background technology]

[0002] Electrical heating elements are now commonly used to heat the exhaust gases in the exhaust gas section downstream of an internal combustion engine or the exhaust gases flowing through the exhaust gas section. The goal pursued here is to more quickly reach a temperature threshold above which effective conversion of harmful substances carried in the exhaust gas can occur. This is necessary because the catalytically active surface of a catalytic converter installed in the exhaust gas section used for exhaust gas aftertreatment can only achieve sufficient conversion of the respective harmful substances once it reaches a minimum temperature, the so-called light-off temperature.

[0003] Known solutions in the prior art require so-called heated catalytic converters, which either have a metal structure connected to a voltage source or a metal-coated ceramic structure that can be heated using an ohmic resistance.

[0004] To establish an electrical contact with the heatable structure, an electrical conductor must be inserted at least at one point through the housing of the exhaust gas section or of the catalytic converter located in the exhaust gas section. It is necessary to ensure that the feed-through is gastight, that electrical insulation between the housing and the electrical conductor is achieved, and that sufficient durability is guaranteed. The electrical conductor is typically made of a solid material, such as a metal bolt.

[0005] German Patent No. 102012110098 discloses a method for manufacturing an electrical feedthrough for powering an electrical exhaust gas heating device in a motor vehicle. The feedthrough has an outer tube through which an electrical conductor passes. The electrical conductor protrudes from the outer tube at at least one end face of the outer tube. The electrical conductor is surrounded by insulating material in the inner space of the outer tube. The feedthrough is formed by cutting a compressed rod material to a predetermined length, and a machining process is used to remove the areas that function as the outer tube and the areas that function as insulating material, thereby forming an electrical feedthrough of the desired length with the electrical conductor protruding out of the outer tube as desired.

[0006] A drawback of the methods for manufacturing electrical feedthroughs known in the prior art is that the compressed rod material used is very expensive, especially since it has a multi-layer structure. Furthermore, the machining process for making the electrical conductors available and cutting the electrical feedthrough to length means that a large portion of the rod material, approximately two-thirds of it, is destroyed and thus wasted. This makes the manufacturing process particularly laborious and expensive. Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to provide a segmented electrical feedthrough with at least equally good technical properties and a suitable manufacturing method that allows for an easy and cost-effective production of the electrical feedthrough. [Means for solving the problem]

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

[0009] One embodiment of the present invention relates to a segmented electrical feedthrough for electrically contacting a heating conductor through a housing, the electrical feedthrough comprising a contact portion and an insulating portion, the insulating portion having an electrical conductor, insulating means, and an outer sleeve, the electrical conductor and insulating means being disposed within the outer sleeve, the electrical conductor being electrically insulated from the outer sleeve by the insulating means, the contact portion being coupled to the electrical conductor at a first end surface, the electrical conductor being connectable to the heating conductor at a second end surface opposite the first end surface, and the contact portion and insulating portion being formed from two distinct elements that are firmly joined together using a joining process.

[0010] Electrical feedthroughs are used to guide electrical conductors through the exhaust gas duct or catalytic converter housing. The feedthrough must be able to withstand the temperatures encountered and be gas-tight to prevent exhaust gases from escaping. The electrical conductors must be electrically insulated from the housing to prevent short circuits.

[0011] Typically, electrical feedthroughs have a connection point on the exterior of the housing that leads to a current-carrying conductor. Typically, this connection point is formed by a threaded bolt that is part of the feedthrough's electrical conductor. The current-carrying conductor is then screwed onto the feedthrough's electrical conductor using a suitable plug.

[0012] A contact part is a part which, on the one hand, can bring about a connection with a current-carrying conductor and, on the other hand, can make a connection with an electrical conductor of an insulating part.

[0013] For this purpose, the contact part preferably has a conical region with an external thread onto which the plug of the current-carrying conductor can be screwed and permanently fixed, the conical design of this region aiding in the installation of the plug by a self-centering effect.

[0014] The contact parts are connected to the electrical conductors of the insulating region by a rigid joining process, in particular by brazing or welding.

[0015] The insulating section itself is formed from a composite material having a central cylindrical electrical conductor surrounded by insulating material, which insulates the electrical conductor from the outer metallic sleeve. In a preferred embodiment, the three different regions have the same axial extension, which allows the insulating section to be cut from a suitable rod material at a length appropriate for the application. This minimizes chips or material loss due to machining.

[0016] The electrical conductor is preferably made of steel, such as 2.4869. The materials selected for the electrical conductor and contact portion may be the same or different, provided that they have the same or similar oxidation resistance and specific electrical resistivity. The insulation is made of, for example, an oxide ceramic. The outer sleeve may also be made of steel.

[0017] The materials of the outer sleeve and the electrical conductor may be the same, but this is not required.

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

[0019] The protrusion of the electrical conductor is preferably arranged on the side of the insulating part that, in the assembled state, faces the heating conductor arranged therein. This asymmetric design also makes it possible to set a unique alignment of the insulating part relative to the contact part, which simplifies assembly and avoids assembly errors.

[0020] It is particularly advantageous if the contact part has a conical part and a cylindrical part, the cylindrical part forming the boundary surface with the insulating part.

[0021] The cylindrical portion of the contact part is particularly advantageous because the electrical conductor typically also has a cylindrical cross section in the insulating part. This makes it particularly easy to connect the contact part to the insulating part. Preferably, the cylindrical portion is aligned concentrically with the electrical conductor. The cylindrical portion preferably has the same diameter as the electrical conductor. In a particularly preferred alternative embodiment, the cylindrical portion can also have a slightly smaller diameter than the electrical conductor, which facilitates assembly and ensures that the cylindrical portion does not come into contact with the insulating material, in particular, does not make conductive contact with the outer sleeve.

[0022] The conical portion is preferably formed in such a way that screwing of the plug can be achieved as easily as possible. Preferably, the conical portion and the cylindrical portion have a common central axis. However, in alternative embodiments, the conical portion may be, for example, at an angle to the central axis of the cylindrical portion.

[0023] It is also advantageous if the insulating portion is formed from a composite material having an internally located electrical conductor that is circumferentially surrounded by a sleeve-like arranged electrical insulating material, the internally located electrical conductor and the electrical insulating material being surrounded by a metallic outer sleeve.

[0024] Such composites can be easily and extensively produced. Cutting the composite to length can be accomplished by a simple severing process with little material scraping. The thickness of the electrical conductor, insulating layer, and outer sleeve can be varied as easily as the materials selected.

[0025] A preferred embodiment is characterized in that the insulating part has a first end face and a second end face, the first end face forming an interface with the contact part of the electrical feedthrough and the second end face forming an interface with the heating conductor and / or the connection part.

[0026] The insulating part is connected to the contact part in the direction of current flow, and the heating conductor to be energized is connected to the insulating part. For this purpose, the insulating part, or more precisely the electrical conductor in the insulating part, has two end faces to which the contact part and the heating conductor to be energized can be connected on the one hand. Since the insulating part is preferably made of rod material, these end faces are preferably located parallel to and opposite each other.

[0027] It is also preferred if the feedthrough has a connection part arranged on the second end face of the insulating part and firmly connected to the electrical conductor of the insulating part.

[0028] The additional connecting portion is preferably formed by a disk-shaped or cylindrical element, which can be attached to the end face of the insulating portion facing away from the contact portion. This connecting portion increases the distance from the insulating portion to the heating conductor. This is particularly advantageous when the electrical conductor does not protrude beyond the insulating material and the outer sleeve. The element forming the connecting portion may have a special shape on the side facing the heating conductor to make it easier to connect to the heating conductor. For example, a structured surface, a surface positioned at a predetermined angle, or a curved surface are conceivable. Preferably, the surface of the connecting portion facing away from the insulating portion is adapted to the shape of the heating conductor to be contacted.

[0029] It is further advantageous if the electrical conductor, the insulating means and the outer sleeve have the same axial extension and the end regions of these elements terminate flush with one another, which is particularly advantageous for an easy and material-compatible production of the insulating part.

[0030] The above-mentioned method problem is solved by a method with the characterizing features of claim 7.

[0031] One embodiment of the present invention relates to a method of manufacturing a segmented electrical feedthrough, wherein a contact portion and an insulating portion are rigidly connected to one another using a bonding process, and the contact portion and insulating portion are rigidly connected to one another at a first end surface of the insulating portion.

[0032] A particular advantage of the method according to the invention is that the insulating part of the outer sleeve, which is connected to the housing in which the electrical conductor is to be guided, can be produced particularly easily and in a material-compatible manner. Since the composite materials used are expensive and the steps otherwise required for machining require long preparation and therefore production times, the use of insulating parts that are easy to assemble and can be produced quickly is particularly advantageous.

[0033] To achieve a fully functional electrical feedthrough, it is necessary to create a connection point for the plug and to enable the connection of a heating conductor on the other side of the insulating part. The segmented implementation allows, in particular, a cost-effective and easy production of the individual parts of the electrical feedthrough. Joining processes, such as brazing in particular, allow the individual parts to be stably and firmly combined into the electrical feedthrough.

[0034] Brazing is an especially advantageous joining process, since the brazing process is carried out in a brazing furnace anyway to produce honeycomb bodies for catalytic converters, and multiple parts of the electrical feedthrough can be easily connected together.

[0035] It is further advantageous if the contact portion and the insulating portion are aligned with one another in such a way that the contact portion is in conductive contact with only the electrical conductor of the insulating portion. Particularly preferably, the electrical conductor and the contact portion are aligned concentrically with one another.

[0036] It is further advantageous if the contact part and the insulating part are fixed to one another using fixing means before carrying out the joining process to form a solid connection.

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

[0038] The individual elements may alternatively have threads, i.e. internal and external threads, so that they can be brazed at the contact points and can be screwed together.

[0039] Alternatively, the elements may have holes into which compliant members are inserted, allowing the elements to be uniquely positioned relative to one another. The compliant members remain in the holes after the brazing process and become part of the electrical conductors.

[0040] Another alternative embodiment can be a tight press fit between the elements, where again a solder is applied to the subsequent contact surfaces between the elements, which solder forms the connection between the elements in a subsequent brazing process.

[0041] In particular, the contact surfaces between the elements, in particular between the electrical conductor and the contact part and between the electrical conductor and the connecting part, if provided, can be further processed so that a positive-locking connection is achieved in addition to the material-bonded connection that occurs during soldering. For this purpose, in particular, pin connections, structured surfaces, engaging elements or protrusions and steps can be provided, which create a positive connection.

[0042] It is also advantageous to fit the contact part with the conical region downwards into a tight mold, first coating the boundary surface arranged in the cylindrical region with solder, then placing the insulating part on the contact part by means of the first end face so that the contact part is in conductive contact with only the electrical conductor, and subsequently subjecting the mold together with the inserted part and the solder layer to the soldering process.

[0043] The brazing process is preferably carried out in a brazing furnace that is also used for brazing the metallic honeycomb body of the catalytic converter, which allows the brazing process to be carried out in parallel, thereby resulting in process economy.

[0044] The components forming the electrical feedthrough are then mounted one after the other on this mold, with solder being applied to the respective planned contact surfaces between the components. The components secured in the mold and soldered accordingly are finally heated to the required temperature in a corresponding furnace, whereby the solder melts and a solid connection is formed.

[0045] The electrical conductors and the brazing filler metal used preferably have a nickel base, and in particular the bolts forming the electrical conductors are preferably made mainly from nickel.

[0046] It is further preferred if the connecting part is placed on the second end surface of the insulating part after the second end surface has been coated with brazing material and before the mould together with the fitted part is subjected to the brazing process.

[0047] Depending on the design of the insulation, especially the electrical conductor, the connecting parts must be provided to provide a sufficient distance between the heating conductor and the outer sleeve to prevent electrical short circuits, and correspondingly, the contact points between the electrical conductor and the connecting parts are also brazed before the entire device is subjected to the brazing process.

[0048] Advantageous developments of the invention are set forth in the dependent claims and in the following description of the drawings.

[0049] The invention will be explained in more detail below on the basis of exemplary embodiments with reference to the drawings. [Brief explanation of the drawings]

[0050] [Figure 1] FIG. 1 is a cross-sectional view of a segmented electrical feedthrough in which the electrical conductors protrude axially beyond the insulating material and outer sleeve on one side. [Figure 2] FIG. 10 is a cross-sectional view of an alternatively formed segmented electrical feedthrough in which the electrical conductor has the same axial extension as the insulating material and outer sleeve, with a connection portion coupled to the electrical conductor that serves as a coupling point for a heating conductor, not shown. [Figure 3] 10 is a cross-sectional view of an alternatively formed segmented electrical feedthrough having an additional form-fit joint between the insulating portion and the contact portion; FIG. [Figure 4]10 is a cross-sectional view of another alternatively formed segmented electrical feedthrough having a different connection between the insulating portion and the contact portion; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0051] 1 shows a segmented electrical feedthrough 1. The feedthrough 1 is formed from a contact portion 2 and an insulating portion 3. The contact portion 2 has a conical portion 4, which may have an external thread so that a corresponding plug (not shown) can be screwed onto the contact portion 2. The contact portion 2 further has a cylindrical portion 5, which continues from the conical portion 4 and forms a contact point with an electrical conductor 6 of the insulating portion 3.

[0052] The contact parts are preferably made of a good electrical conductor material that is characterized by high oxidation resistance and low specific electrical resistivity, a preferred material being steel 2.4869 for example.

[0053] The contact portion 2 is followed by an insulating portion 3. As can be seen in Figure 1, the insulating portion 3 is formed from an electrical conductor 6, an insulating material 7, and an outer sleeve 8. The electrical conductor 6 preferably has a slightly larger diameter than the cylindrical portion 5. In the embodiment shown in Figure 1, the cylindrical portion has a diameter of 7.5 millimeters, while the electrical conductor 6 has a diameter of 8 millimeters. The dimensions are exemplary, but give a sense of the preferred dimensional ratios.

[0054] 1, the electrical conductor 6 has a longer axial extension than the insulating material 7 and the outer sleeve 8. This results in a protrusion of the electrical conductor 6, which facilitates the coupling of a heating conductor, not shown.

[0055] The protrusions of the electrical conductors 6 can be obtained, for example, by machining away the outer sleeve 8 and the insulating material 7 .

[0056] 1 also shows a mold 9, which is used to correctly position the individual elements of the segmented electrical feedthrough relative to one another before the soldering process. For this purpose, the mold 9 has recesses that are adapted to the individual elements, which force a unique positioning of the elements relative to one another.

[0057] An alternative embodiment of the segmented electrical feedthrough 10 is shown in Figure 2. Elements that are the same as those in Figure 1 have the same reference numerals.

[0058] Unlike in FIG. 1, the electrical feedthrough 10 additionally has a connecting portion 11, which is connected to an electrical conductor 12 at its end facing away from the contact portion. In the embodiment of FIG. 2, the electrical conductor 12 does not protrude beyond the insulating material 7 and the outer sleeve 8. Nevertheless, to ensure that the heating conductor (not shown) is sufficiently spaced from the outer sleeve 8, the cylindrically shaped connecting portion 11 is connected to the electrical conductor 12. This is likewise achieved by soldering the contact points and then brazing. Like the contact portion 3, the connecting portion 11 also has a smaller diameter than the electrical conductor 12.

[0059] The mould 13 is extended so that the connecting portion 11 is also uniquely positioned relative to the remaining elements and fixed for the brazing process.

[0060] 3 shows an alternatively shaped segmented electrical feedthrough 14. The outer sleeve 8 and insulating material 7 are shaped as in FIG. 1. The contact portion 15 has a recess 18 in the cylindrical portion 16 that forms an interface with the electrical conductor 17. The recess 18 is centrally located. The electrical conductor 17 has a pin 19 that corresponds to the recess 18. During assembly, the pin 19 is inserted into the recess 18, thereby forming a form-locking joint and thus preventing relative movement, at least in the radial direction.

[0061] If the pin 19 forms a press or interference fit with the recess 18, an axial lock can also be formed when the two elements are pressed together, i.e., when the pin 19 is pressed into the recess 18.

[0062] 4 shows an alternative embodiment of the connection between the electrical conductor 20 and the cylindrical part 22 of the contact piece. Here, the electrical conductor 20 has a number of pins 21 or a completely or partially surrounding edge on its radially outer periphery. The cylindrical part can be inserted into a receiving section thus formed in the electrical conductor 20, thereby ensuring at least a radial fixation, or, if a press fit is used, an axial fixation as well.

[0063] The different features of the individual embodiments can also be combined with one another.

[0064] The examples of Figures 1 and 4 are not of a limiting nature and are used to illustrate the idea of ​​the invention.

Claims

1. A segmented electrical feedthrough (1, 10, 14) for electrically contacting a heating conductor through a housing, comprising a contact portion (2, 15) and an insulating portion (3), a segmented electrical feedthrough (1, 10, 14) in which the insulating portion (3) has an electrical conductor (6, 12, 17, 20), an insulating means (7), and an outer sleeve (8), the electrical conductor (6, 12, 17, 20) and the insulating means (7) are disposed within the outer sleeve (8), the electrical conductor (6, 12, 17, 20) is electrically insulated from the outer sleeve (8) by the insulating means (7), the contact portion (2, 15) is coupled to the electrical conductor (6, 12, 17, 20) at a first end face, and the electrical conductor (6, 12, 17, 20) is connectable to a heating conductor at a second end face opposite to the first end face; the contact portion (2, 15) and the insulating portion (3) are formed from two different elements that are firmly connected to each other using a bonding process; the contact portion (2, 15) has a conical portion (4) and a cylindrical portion (5, 16, 22), the cylindrical portion (5, 16, 22) forming an interface with the insulating portion (3); The cylindrical portion (16) has a recess (18) arranged at the center of the interface, and the electrical conductor (17) has a pin (19) corresponding to the recess (18), so that when the electrical conductor (17) and the contact portion (15) are assembled, the pin (19) is inserted into the recess (18) to form a form-fitting joint. A segmented electrical feedthrough (1, 10, 14) characterized in that:

2. 2. The segmented electrical feedthrough (1, 10, 14) according to claim 1, wherein the insulating portion (3) is formed from a composite material having an internally located electrical conductor (6, 12, 17, 20) circumferentially surrounded by a sleeve-like arranged electrical insulating material (7), and wherein the internally located electrical conductor (6, 12, 17, 20) and the electrical insulating material (7) are surrounded by a metallic outer sleeve (8).

3. 2. The segmented electrical feedthrough (1, 10, 14) according to claim 1, characterized in that the insulating part (3) has a first end face and a second end face, the first end face forming an interface with the contact part (2) of the electrical feedthrough (1, 10, 14), and the second end face forming an interface with the heating conductor and / or connection part (11).

4. 2. The segmented electrical feedthrough (10) according to claim 1, characterized in that the electrical feedthrough (10) has a connecting portion (11) arranged on the second end surface of the insulating portion (3) and firmly connected to the electrical conductor (12) of the insulating portion (3).

5. 5. A method for manufacturing a segmented electrical feedthrough (1, 10, 14) according to any one of claims 1 to 4, wherein the contact portion (2, 15) and the insulating portion (3) are firmly connected to one another using a bonding process, characterized in that the contact portion (2, 15) and the insulating portion (3) are firmly connected to one another at the first end face of the insulating portion (3).

6. 6. The method according to claim 5, characterized in that the contact portion (2, 15) and the insulating portion (3) are aligned with each other in such a way that the contact portion (2, 15) is in conductive contact with only the electrical conductors (6, 12, 17, 20) of the insulating portion (3).

7. 6. The method according to claim 5, characterized in that the contact part (2, 15) and the electrical conductor (17) are fixed together using the pin (19) and the recess (18) before carrying out the joining process to form the solid connection.

8. 6. The method according to claim 5, further comprising inserting the contact part (2, 15) with the conical region (4) downwards into a tight mold (9, 13), first coating the interface surface located in the cylindrical region (5, 16, 22) with solder, then placing the insulating part (3) on the contact part (2, 15) by means of the first end face so that the contact part (2, 15) is in conductive contact with only the electrical conductor (6, 12, 17, 20), and subsequently subjecting the mold (9, 13) together with the inserted part and the solder layer to a soldering process.

9. 9. The method according to claim 8, characterized in that after coating the second end surface with brazing filler and before subjecting the mold (13) with the inserted part to the brazing process, a connecting part (11) with the heating conductor is placed on the second end surface of the insulating part (3).

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