Device for electrically contacting a heat conductor

Abstract

The invention relates to a device for electrically contacting a heat conductor (7, 15) through a housing of an exhaust gas section, comprising an electric conductor (1, 10) which is designed as a metal pin, a metal outer sleeve (3) through which the electric conductor (1, 10) is guided, and an insulating means (2) which is arranged between the electric conductor (1, 10) and the outer sleeve (3), wherein the outer sleeve (3) is bonded to the housing, The heat conductor (7, 15) is made of a metal honeycomb body which is arranged in the interior of the housing, and exhaust gas can flow through the housing along a main flow direction which corresponds to the axial extension of the housing. The electric conductor (1, 10) is aligned along the axial direction of extension of the housing.

Description

[0001] Description

[0002] Device for electrically contacting a heating conductor

[0003] Technical area

[0004] The invention relates to a device for electrically contacting a heating conductor through a housing of an exhaust gas path, with an electrical conductor which is designed as a metallic bolt, with a metallic outer sleeve through which the electrical conductor is guided and with an insulating means which is arranged between the electrical conductor and the outer sleeve, wherein the outer sleeve is materially connected to the housing, wherein the heating conductor is formed by a metallic honeycomb body which is arranged in the interior of the housing, wherein the housing can be flowed through with exhaust gas along a main flow direction which corresponds to the axial extent of the housing.

[0005] State of the art

[0006] 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.

[0007] Known solutions in the prior art include so-called heated catalysts, which have a metallic structure connected to a voltage source or a metallically coated ceramic structure that can be heated using ohmic resistance. To electrically contact the heatable structure, an electrical conductor must be introduced at least once through the housing of the exhaust system or a catalyst arranged 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 metallic bolt.

[0008] 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.

[0009] The heating conductor is connected inside the housing by connecting the metallic structure forming the heating conductor to the axial end face of the bolt. This is due to the fact that the electrical feedthrough is in the radial direction of the housing.

[0010] A disadvantage of the devices known in the prior art is that the radial orientation of the electrical feedthrough requires more space. This is particularly disadvantageous since electric heaters are increasingly being used in close proximity to the combustion engine, where the available space is extremely limited. In addition to the radial orientation and arrangement of the electrical feedthrough itself, the electrical contacting of the inner conductor with an electrical supply line outside the housing is also difficult due to the limited space available.

[0011] Description of the invention, task, solution, advantages

[0012] Therefore, the object of the present invention is to provide a device for electrically contacting a heating conductor arranged in an exhaust gas line, which is optimized with regard to the installation space requirement.

[0013] The object with regard to the device is achieved by a device having the features of claim 1.

[0014] One embodiment of the invention relates to a device for electrically contacting a heating conductor through a housing of an exhaust gas path, with an electrical conductor which is designed as a metallic bolt, with a metallic outer sleeve through which the electrical conductor is guided and with an insulating means which is arranged between the electrical conductor and the outer sleeve, wherein the outer sleeve is integrally connected to the housing, wherein the heating conductor is formed by a metallic honeycomb body which is arranged in the interior of the housing, wherein the housing can be flowed through with exhaust gas along a main flow direction which corresponds to the axial extent of the housing, wherein the electrical conductor is aligned along the axial extent direction of the housing.

[0015] The housing is usually formed by a tube through which fluid can flow along a main flow direction. This direction corresponds to the axial extent of the housing. According to the invention, the electrical conductor is aligned along this axial direction. It can also be positioned at a small angle to this axial direction. The electrical conductor thus penetrates the housing at an axial outer surface of the housing, rather than at a radially oriented outer surface. This allows for a significantly space-saving arrangement of the electrical conductor and thus of the entire electrical feedthrough.

[0016] It is particularly advantageous if the electrically conductive contact between the heating conductor and the electrical conductor is formed on a radially aligned surface of the electrical conductor. The heating conductor, which is usually disc-shaped and arranged within the housing, is formed by a metallic honeycomb body. The honeycomb body is formed from a plurality of stacked metal foils that are smooth and / or at least partially structured. The layer stack produced in this way is rotated about at least one pivot point and forms the heating conductor referred to as the heating disc. The wound layer packages run out at least at one point on the outer circumference of the heating disc and form a free end. The electrical contact of the heating conductor by means of the electrical conductor takes place at this free end.

[0017] Due to the inventive arrangement of the electrical conductor in an axial direction, the contact surface between the free end of the heating conductor and the electrical conductor is preferably formed on a radial end face of the electrical conductor.

[0018] It is also advantageous if the electrical conductor has a flattened surface at its end projecting into the housing, which is aligned in the radial direction of the electrical conductor.

[0019] The electrical conductor, designed as a metallic bolt, has a cylindrical shape in its basic state at its end region protruding into the housing. In order to establish advantageous electrical contact with the heating conductor, it is advantageous if the cylindrical outer surface is flattened on at least one section of the electrical conductor. The surface aligned in the radial direction of the electrical conductor serves as a contact surface with the heating conductor. A preferred exemplary embodiment is characterized in that the flattened surface has at least one recess acting as a solder reservoir. The flattened surface of the electrical conductor is preferably brought into contact with the free end of the heating conductor and permanently connected by means of a soldering process.To ensure process reliability and simplify the process, it is advantageous if the flattened surface has a recess that can be filled with a solder material. The recess can extend along the entire flattened surface or be formed only in sections.

[0020] It is also preferable if the electrical conductor has a bevel at its end region projecting into the housing, which reduces the axial end face of the electrical conductor and runs from the axial end face to the flattened surface.

[0021] The bevel serves to create an insertion slope. This, in particular, reduces the axial end face of the electrical conductor. Furthermore, the bevel is aligned such that it transitions from the axial end face of the electrical conductor into the radially oriented flattened surface. When inserting the electrical conductor into the housing, the free end of the heating conductor is thus advantageously guided toward the flattened surface to contact the electrical conductor.

[0022] Furthermore, it is advantageous if the electrical conductor has a slot introduced from its axial end face, which runs completely through the electrical conductor in the radial direction, wherein the heating conductor is guided through this slot.

[0023] Such a slot, which preferably runs completely through the electrical conductor, forms two radial connection surfaces on the electrical conductor. The free end of the heating conductor can be guided through this slot and connected to the electrical conductor. The electrical conductor encloses the free end of the heating conductor on both sides for this purpose. The slot can penetrate the axial end face of the electrical conductor, forming a U-shaped receptacle through the slot.

[0024] Furthermore, it is advantageous if the heating conductor is guided through the slot in the electrical conductor, wherein a ceramic wedge is pushed between at least two layers of the heating conductor designed as a honeycomb body, which creates a clamping between the heating conductor and the electrical conductor in the region of the slot.

[0025] In order to strengthen the connection between the heating conductor and the electrical conductor, a clamping part can be provided which can be pushed between individual metal foils of the free end of the heating conductor and thus creates a clamping between the heating conductor and the receiving area of ​​the electrical conductor formed by the slot.

[0026] It is also expedient if the electrical conductor is routed through the housing at a point outside the permeable cross-section of the housing. This is advantageous so that, despite the axial orientation of the electrical conductor, the actual permeable cross-sectional area of ​​the housing is not reduced. The free end of the heating conductor is therefore preferably routed out of the permeable cross-section of the housing into a further area, for example, into a secondary chamber. The electrical contact between the heating conductor and the electrical conductor is then created in this area.

[0027] Advantageous further developments of the present invention are described in the subclaims and in the following description of the figures.

[0028] Short description of the drawings

[0029] The invention will now be explained in detail using exemplary embodiments with reference to the drawings. In the drawings: Fig. 1 shows a perspective view of the electrical conductor with a flattened surface,

[0030] Fig. 2 is a perspective view of an electrical conductor, wherein the conductor has a slot introduced from the axial end face,

[0031] Fig. 3 is a perspective view of the electrical conductor, wherein the electrical conductor is in contact with the heating conductor via the radially aligned flattened surface,

[0032] Fig. 4 is a perspective view through an electrical conductor according to Figure 2, wherein the heating conductor is guided through the formed slot,

[0033] Fig. 5 is a view of the electrical conductor with a flattened radially oriented surface, wherein the electrical conductor has a bevel at its axial end region,

[0034] Fig. 6 shows an electrical conductor with a flattened radially oriented surface, the surface having a recess which serves as a solder reservoir, and

[0035] Fig. 7 shows an electrical conductor according to Figure 2, wherein the heating conductor guided through the slot is clamped in the slot by means of a ceramic wedge.

[0036] Preferred embodiment of the invention

[0037] Figure 1 shows an electrical conductor 1 formed from a metal bolt. This conductor is guided through a sleeve-like insulating means 2, which in turn is enclosed in a metal sleeve 3. The electrical conductor 1 has two free ends 4, 5. In the final assembled state, the free end 4 is positioned outside the housing of the exhaust system (not shown). The free end 5 is positioned inside the housing and serves for the electrical connection to the heating conductor (not shown).

[0038] The free end 5 is flattened over a portion of the axial extent of the electrical conductor 1, so that a flat surface 6 is formed on a radially oriented side of the electrical conductor 1. The surface 6 serves as a contact surface for the heating conductor (not shown).

[0039] Figure 2 shows an alternative embodiment of an electrical conductor 10. The basic structure corresponds to that of the electrical conductor 1 in Figure 1. In contrast to the flattened surface 6 in the example of Figure 1, the electrical conductor 10 has a slot 12 at the free end 11 located within the housing, which divides the free end region into two sections. The two sections created by the slot 12 each form a radial surface 13, 14, which serves as a contact surface for the heating conductor (not shown).

[0040] The heating conductor, in particular the free end of the layer stack forming the heating conductor, can be guided through the slot 12 and connected on both sides to the radially aligned surfaces 13, 14.

[0041] Figure 3 shows an electrical conductor 1 analogous to Figure 1. In Figure 3, the free end of a layer stack forming the heating conductor 7 is connected to surface 6. It can be clearly seen that the contact of the heating conductor 7 is made on a radial outer surface 6 of the electrical conductor 1.

[0042] The free end 5 of the electrical conductor 1 having the surface 6 engages in the axial direction in the plane in which the heating conductor 7 is arranged.

[0043] Figure 3 shows an electrical conductor 10 according to Figure 2. In Figure 4, a free end of the layer stack 15 is inserted into the slot 12 and connected to the electrical conductor 10 via the contact surfaces 13, 14 formed by the slot. Here, too, it can be clearly seen that the connection of the electrical conductor 10 to the heating conductor 15 takes place via radially aligned contact surfaces 13, 14 of the electrical conductor 10.

[0044] Figure 5 shows an alternative embodiment of an electrical conductor 1, as shown in Figure 1. In addition to the radially oriented surface 6 at the free end 5 of the electrical conductor 1, an inclined surface 8 is formed, which reduces the axial end surface 9 of the electrical conductor and forms a transition to the radially oriented surface 6.

[0045] The bevel 8 serves as an insertion aid and is intended to ensure that the free end of the heating conductor does not hook on the axial end face 9 when the electrical conductor 1 is inserted, but slides past it and comes into contact with the radially aligned surface 6.

[0046] Figure 6 shows an alternative embodiment of the electrical conductor 1 of Figure 1. Additionally, the radially oriented surface 6 has a recess 16, which serves as a solder reservoir. In the embodiment of Figure 6, the recess 16 is formed by a bore formed by the axial end face.

[0047] Figure 7 shows an alternative embodiment of an electrical conductor 10, wherein a free end of a heating conductor 15 is inserted into the slot 12. Additionally, a clamping element 17, a wedge in the case of Figure 7, is inserted between the layers of the heating conductor 15, thereby clamping the layers of the heating conductor 15 in the slot 12 of the electrical conductor 10. This further increases the stability of the connection. Preferably, the clamping element 17 is made of a ceramic and thus electrically non-conductive material.

[0048] The different features of the individual embodiments can also be combined with each other.

[0049] The embodiments of Figures 1 to 7 are not limiting in nature and serve to clarify the inventive concept. List of reference symbols

[0050] 1 . electrical conductor

[0051] 2. Insulating agents

[0052] 3. Outer sleeve

[0053] 4. free end

[0054] 5. free end

[0055] 6. radially aligned surface

[0056] 7. Heating conductor

[0057] 8. Slope

[0058] 9. axial end face

[0059] 10. electrical conductor

[0060] 11 . free end

[0061] 12. Slot

[0062] 13. radially aligned surface

[0063] 14. radially aligned surface

[0064] 15. Heating conductor

[0065] 16. Deepening

[0066] 17. Clamping element

Claims

Patent claims 1. Device for electrically contacting a heating conductor (7, 15) through a housing of an exhaust gas line, with an electrical conductor (1, 10) which is designed as a metallic bolt, with a metallic outer sleeve (3) through which the electrical conductor (1, 10) is guided and with an insulating means (2) which is arranged between the electrical conductor (1, 10) and the outer sleeve (3), wherein the outer sleeve (3) is integrally connected to the housing, wherein the heating conductor (7, 15) is formed by a metallic honeycomb body which is arranged in the interior of the housing, wherein exhaust gas can flow through the housing along a main flow direction which corresponds to the axial extent of the housing, characterized in that the electrical conductor (1, 10) is aligned along the axial extent of the housing.

2. Device according to claim 1, characterized in that the electrically conductive contact between the heating conductor (7, 15) and the electrical conductor (1, 10) is formed on a radially aligned surface (6, 13, 14) of the electrical conductor (1, 10).

3. Device according to one of the preceding claims, characterized in that the electrical conductor (1) has a flattened surface (6) at its end projecting into the housing, which is aligned in the radial direction of the electrical conductor (1).

4. Device according to claim 3, characterized in that the flattened surface (6) has at least one recess (16) acting as a solder reservoir.

5. Device according to one of the preceding claims 3 or 4, characterized in that the electrical conductor (1) has a bevel (8) at its end region (5) projecting into the housing, which bevel covers the axial end face (9) of the electrical conductor (1). nert and runs from the axial end face (9) towards the flattened surface (6).

6. Device according to one of the preceding claims, characterized in that the electrical conductor (10) has a slot (12) introduced from its axial end face, which slot runs completely through the electrical conductor (10) in the radial direction, the heating conductor (15) being guided through this slot (12).

7. Device according to claim 6, characterized in that the heating conductor (15) is guided through the slot (12) in the electrical conductor (10), wherein a ceramic wedge (17) is pushed between at least two layers of the heating conductor (15) designed as a honeycomb body, which creates a clamping between the heating conductor (15) and the electrical conductor (10) in the region of the slot (12).

8. Device according to one of the preceding claims, characterized in that the electrical conductor (1, 10) is guided through the housing at a point which is arranged outside the flow-through cross-section of the housing.

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