Bushing for an electrical conductor

Abstract

The invention relates to a bushing (1) for an electrical conductor (2), wherein the electrical conductor (2) can be guided out of a housing (3) of an exhaust-gas system. The invention is characterized in that the electrical conductor (2) is designed to guide a component out of the housing (3) in an insulated manner, wherein a temperature gradient is formed over a length of the electrical conductor (2) in order to lower the temperature of the electrical conductor (2) within the bushing (1).

Description

[0001] Feedthrough for an electrical conductor

[0002] The invention relates to a feedthrough for an electrical conductor, wherein the electrical conductor can be led out of a housing of an exhaust system.

[0003] Such electrical conductors can be designed for connecting an electric heater. Such a heater is arranged, for example, in an exhaust system to more quickly reach a desired temperature threshold, above which an effective conversion of the pollutants carried in the exhaust gas can take place.

[0004] DE 102014218 983 B4 discloses a feedthrough for an electrical conductor, which serves to connect an electrically heatable heating disk. The feedthrough has an inner conductor guided in an insulation and an outer sleeve. The insulation is formed from a porous ceramic layer with at least two layers.

[0005] DE 102021 209264 B3 describes a further general feedthrough of an electrical conductor, wherein the insulation is made of a glass ceramic with a specific volume resistance.

[0006] Generally, the electrical conductor within the bushing experiences high temperatures. Therefore, the electrical conductor or an electrode cannot be contacted using commercially available connectors, as they cannot withstand the high temperatures. A current load, for example, can be up to 320 A. Commercially available connectors cannot be used for such high current loads and the resulting high temperatures, especially in an exhaust gas box environment where temperatures of around 200 °C prevail.

[0007] Furthermore, the electrical conductor leading out should be completely insulated to prevent short circuits with surrounding components, such as the housing of the exhaust system, especially the exhaust box. For example, short circuits caused by water, splash water, ice formation, dirt, oil / grease, fuel, and other external influences that could lead to a short circuit between the current-carrying component and the box housing should be avoided. It is particularly important, for example, to meet the ADR requirements, which stipulate protection against short circuits.

[0008] Furthermore, the duct should be designed to be essentially tight enough to prevent the escape of exhaust gases.

[0009] A further requirement for such bushings is that the electrical conductor must be protected from dirt, moisture, salt, oils, grease, fuel, corrosion and other external influences as well as other media.

[0010] The object of the present invention is to provide a feedthrough for an electrical conductor which overcomes the aforementioned disadvantages

[0011] According to the invention, this object is achieved by a bushing for an electrical conductor having the features in claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments and further developments emerge from the dependent claims.

[0012] At the core of the feedthrough according to the invention, the electrical conductor is designed for the insulated feedthrough of an electrical heater from the housing, wherein a temperature gradient is formed over a length of the electrical conductor in order to lower the temperature of the electrical conductor within the feedthrough. The temperature gradient is preferably designed such that the electrical conductor has a higher temperature on the side of the feedthrough on which it is connected to the electrical heater than on an opposite side on which it can be contacted with a plug-in connector. If the temperature of the electrical conductor is lowered within the feedthrough, no special materials are required to connect the electrical conductor to a plug-in connector outside the feedthrough. In particular, commercially available plugs can then be used to supply the electrical heater with power.

[0013] The bushing for an electrical conductor is designed to lead the electrical conductor out of a housing of an exhaust system. The bushing electrically insulates the electrical conductor from other components, thus protecting it from short circuits. The insulated electrical bushing also provides protection against contamination, moisture, and other media. In particular, the ADR requirement, which includes a requirement against short circuits, can be met.

[0014] The electric heater can be arranged in an exhaust box in order to be completely insulated via the insulated electrical feedthrough from the exhaust box.

[0015] The electrical conductor can preferably be guided through a sleeve for passage, with insulation arranged between the sleeve and the electrical conductor. The insulation is designed in particular to separate the electrical conductor from the sleeve in order to prevent a short circuit between the sleeve and the electrical conductor. The sleeve serves in particular to guide the electrical conductor out of the housing. Advantageously, the sleeve is made of a weldable material so that the sleeve can be welded to the housing. While the sleeve can continue to have a high temperature, the temperature of the electrical conductor within the sleeve is reduced.

[0016] According to a very advantageous development of the concept, the insulation can be provided with magnesium oxide or ceramic. Furthermore, glass ceramic, for example, can be used. These materials serve as insulation between the current-carrying electrical conductor and the outer sheath, in particular formed by the sleeve.

[0017] According to an advantageous embodiment, the electrical conductor may be formed at least partially from steel or a nickel alloy. The electrical conductor, i.e., the current-carrying components, are preferably designed for minimal contact resistance. In particular, the diameter of the current-carrying components can be adapted to a high current load. In particular, it should be ensured that a reduction in the insulation, i.e., a reduction in the thickness of the insulation, is avoided.

[0018] A further advantageous embodiment can provide for the diameter of the electrical conductor to be adapted to the current load and thermal conduction of the exhaust gas. For example, stainless steel can be used to form the electrical conductor. In another embodiment, the electrical conductor can also be made of steel or a nickel alloy, such as Inconel. Stainless steel has the advantage of being less susceptible to corrosion. However, stainless steel has a disadvantage in that it has a higher specific resistance, which is why a design based on the cross-section or diameter is advantageous.

[0019] For example, a high current flow is advantageous for heating by current loading, but this improves heat conduction and heats the electrodes more intensely by the exhaust gas. Therefore, an optimization between the cross-section and length of the electrode (or conductor) should be found to minimize heat conduction and minimize ohmic heating by the current loading. For example, a longer length can have a positive effect on heat conduction but a negative effect on resistance. Likewise, an increase in diameter can have a positive effect on heating by current loading but a negative effect on heat conduction by exhaust gas.

[0020] According to a very advantageous development of the idea, it can be provided that the electrical conductor has a transition from a steel material to a copper material or from a nickel alloy to a copper material. Such a transition can be designed such that two different materials meet or are fixed to one another. In order to keep the contact resistance as low as possible, a welded connection can be used, which is produced, for example, by friction welding. For example, in the direction of the electric heater, the electrical conductor can be made of a steel with moderate specific resistance in order to withstand the high temperatures at the electric heater. This can be achieved, for example, by welding the electrical conductor to the heater, i.e. by bringing it into direct contact.Within the feedthrough, a transition to a material with low resistivity can be provided in order to reduce the temperature development within the feedthrough.

[0021] According to an advantageous embodiment, it can be provided that the electrical conductor has a joint in a region within the sleeve, at which a section of the electrical conductor made of a steel material or a nickel alloy contacts a section made of a copper material. Such a joint can be designed, for example, as a lap joint, wherein the two sections made of different materials overlap and are thus fixed to one another. Furthermore, one section can be inserted into the other section, forming a type of butt joint. In this case, one conductor can have a shaped tip so that it can be inserted into the other conductor in a pointed manner.

[0022] A further advantageous embodiment can provide for a reduction in the temperature of the electrical conductor within the feedthrough to below 180°C, so that the feedthrough can be connected to a conventional connector. To achieve this temperature range, copper or a copper alloy can be used for a section of the electrical conductor.

[0023] According to a very advantageous development of the concept, the sleeve can be made of a weldable material, allowing the sleeve to be welded to the housing. This allows the transition to be mounted at any desired position on the housing, including, for example, any position in an exhaust aftertreatment system.

[0024] According to an advantageous embodiment, the bushing can fulfill an ADR requirement. In particular, this avoids protection against a short circuit between the electrical conductor and the housing from which the electrical conductor is led. The ADR requirement stipulates that electrical contacts must be insulated against short circuits.

[0025] Further advantageous embodiments of the inventive bushing for an electrical conductor also emerge from the exemplary embodiment, which is described in more detail below with reference to the figures. In the figures:

[0026] Fig. 1 shows a possible embodiment of a bushing according to the invention;

[0027] Fig. 2 shows a possible embodiment of a bushing according to the invention with a continuous conductor; and

[0028] Fig. 3 shows a possible embodiment of a bushing according to the invention with a joint within the conductor;

[0029] Fig. 4 further possible embodiments of a bushing according to the invention with differently designed joints within the conductor.

[0030] The illustration in Fig. 1 shows a possible embodiment of the feedthrough 1 in a longitudinal section. The section runs along the length of an electrical conductor 2, wherein the electrical conductor 2 is led out of a housing 3 of an exhaust system. In the left-hand area of ​​the illustration, the electrical conductor 2 is therefore connected to an electrical heater 4, which is led out of the housing 3 insulated by the electrical conductor 2. In the right-hand area of ​​the illustration, the electrical conductor 2 is connected to a plug connector 12. The plug connector 12 is in particular a commercially available plug connector that is not adapted to particularly high temperature requirements. In particular, it is sufficient to use a plug connector 12 that is designed for a temperature of 200°C or less, in particular for a temperature of 180°C.This is possible because a temperature gradient is formed along the length of the electrical conductor 2 in order to lower the temperature of the electrical conductor 2 within the feedthrough 1. The temperature reduction occurs in such a way that a high temperature present in the direction of the electrical heater 4 is reduced along the length of the electrical conductor 2 within the feedthrough 1 to a position outside the housing 3. As a result, the connector 12 is not exposed to high temperatures.

[0031] The feedthrough 1 can have a sleeve 5 in which the electrical conductor 2 is guided. The sleeve can be welded to the housing 3 via weld seams 13. In order to prevent a short circuit between the electrical conductor 2 and the sleeve 5, an insulation 6 is provided which guides the electrical conductor 2 in a spaced-apart manner to the sleeve 5 within the feedthrough 1. The insulation 6 is made in particular from a magnesium oxide, a ceramic or a glass ceramic. If the electrical conductor 2 is protected from short circuits with the housing 3, the ADR requirement can advantageously be met. In particular, a seal can be achieved in the transition area between the sleeve 5 and the plug connection 12 in order to meet the ADR requirement. This can advantageously be achieved by lowering the temperature up to the plug 12.Furthermore, the passage 1 is preferably designed to be sealed so that the penetration of dirt, moisture, salt, or other media can be prevented. Furthermore, the escape of exhaust gas through the passage 1 can be prevented.

[0032] Fig. 2 shows the bushing 1, consisting of an electrical conductor 2, a sleeve 5 and an insulation 6. The sleeve 5 is preferably made of a weldable material. The insulation 6 can be designed as explained above. The electrical conductor 2 is made in particular of pure steel or a nickel alloy, such as Inconel. It is advantageous if a diameter of the electrical conductor 2 is adapted to the current load and to the heat conduction through the exhaust gas. In particular, it is advantageous if the current-carrying elements, ie in particular the electrical conductor 2, are designed for the smallest contact resistance.

[0033] A further embodiment of the bushing 1 can be seen in Fig. 3. The same components are provided with the same reference numerals, so that they need not be discussed in detail here. In contrast to Fig. 2, a transition 7 is shown here within the bushing 1, wherein a material transition of the electrical conductor 2 occurs at the transition 7. In this way, different sections can be formed in which the electrical conductor 2 is made of different materials. In the left-hand area of ​​the illustration, which is oriented in the direction of the electric heater 4, a steel material 8 or a nickel alloy 10 can be used for the electrical conductor 2. In the right-hand area of ​​the illustration, a copper material 9 can be used for the electrical conductor 2. The different materials, i.e. the different sections, contact one another at the transition 7, which can in particular be designed as a joint 11.The joint 11 can have different configurations, as described in Figure 4.

[0034] Due to the different materials, i.e., the sections with different materials, the electrical conductor 2 can particularly advantageously have a temperature gradient within the feedthrough, so that the temperature is lowered away from the electric heater 4. This results in a particularly low temperature at a free end of the feedthrough 1, so that commercially available connectors 12 can be used to contact the electrical conductor 2.

[0035] Fig. 4 shows different designs of the joint 11, as it can be designed, for example, in the design in Fig. 3. Fig. 4 (a) shows a design as a lap joint, wherein the two sections consisting of a steel material 8 or a nickel alloy 10 and consisting of a copper material 9 overlap. The transition 7 is therefore shaped as an overlap joint, wherein the different sections can be connected to one another by the overlap. Fig. 4 (b) shows a further possibility, wherein one section of the electrical conductor 2 can be inserted into another section of the electrical conductor 2. In this way, a type of butt joint can be formed. It is also conceivable for the two sections to have different diameters. Furthermore, the two sections can also have identical diameters.This can be achieved, in particular, by having one of the sections have a point, as shown in Fig. 4 (c). This allows a joint 11 to be formed, with one of the sections projecting pointedly into the other section.

[0036] The examples shown illustrate possibilities for forming a transition from a steel material 8 or a nickel alloy 10 to a copper material 9. The diameters of the current-carrying elements, i.e., the sections of the electrical conductor 2, can be adapted to the high current loads. At the same time, it must be ensured that the insulation 6 remains sufficiently thick. It is therefore advantageous to design the current-carrying elements for minimal transition resistance.

[0037] For the feedthrough 1 according to the invention, the advantage can therefore be exploited that an electrical conductor 2 made of a copper material has a low specific resistance. This can support or particularly advantageously bring about a reduction in temperature within the electrical conductor 2 in the feedthrough 1. As a result, the temperature of the electrical conductor 2 can be greatly reduced from the inside to the outside, i.e. from the electrical heater 4 out of the housing 3, by suitable material selection. In the direction of the electrical heater 4, steel with a moderate specific resistance is therefore used in particular. This is necessary in particular because high temperatures prevail at the electrical heater 4. The different materials can be connected to one another within the transition 7.For example, a lap joint from copper to steel, a plugged connection from copper to steel, a plugged connection from copper to steel with a tip, and a wire transition from steel to copper can be made. Instead of steel, Inconel, for example, can be used. A copper alloy can also be used instead of copper.

[0038] In a further embodiment not shown, insulation discs can be attached, which can prevent the insulation 6 from being eroded or removed.

Claims

Patent claims 1. A feedthrough (1) for an electrical conductor (2), wherein the electrical conductor (2) can be led out of a housing (3) of an exhaust system, characterized in that the electrical conductor (2) is designed for the insulated feedthrough of a component from the housing (3), wherein a temperature gradient is formed over a length of the electrical conductor (2) in order to reduce the temperature of the electrical conductor (2) within the feedthrough (1).

2. Feedthrough (1) according to claim 1, characterized in that the electrical conductor (2) is guided in a sleeve (5) for feeding through, an insulation (6) being arranged between the sleeve (5) and the electrical conductor (2).

3. Feedthrough (1) according to claim 2, characterized in that the insulation (6) contains magnesium oxide or ceramic.

4. Feedthrough (1) according to claim 1, 2 or 3, characterized in that the electrical conductor (2) is at least partially made of steel or a nickel alloy.

5. Feedthrough (1) according to one of claims 1 to 4, characterized in that a diameter of the electrical conductor (2) is adapted to a current load and a heat conduction of the exhaust gas.

6. Feedthrough (1) according to one of claims 1 to 5, characterized in that the electrical conductor (2) has a transition (7) from a steel material (8) to a copper material (9) or from a nickel alloy (10) to a copper material (9).

7. Feedthrough (1) according to one of claims 2 to 6, characterized in that the electrical conductor (2) has a joint (11) in a region inside the sleeve (5), at which a section of the electrical conductor made of a steel material (8) or of a nickel alloy (10) contacts a section made of a copper material (9).

8. Feedthrough (1) according to one of claims 1 to 7, characterized in that the temperature of the electrical conductor (2) within the feedthrough (1) is reduced to below 180 °C, so that the feedthrough can be connected to a conventional plug connector (12).

9. Feedthrough (1) according to one of claims 2 to 8, characterized in that the sleeve (5) is made of a weldable material, so that the sleeve (5) can be welded to the housing (3).

10. Implementation (1) according to one of claims 1 to 9, characterized in that an ADR requirement is met with the implementation (1).

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