Device for electrically contacting heating conductor

Abstract

The invention relates to a device for electrically contacting a heating conductor in an exhaust gas path, the heating conductor being arranged in a metal housing through which at least one electrical conductor is passed in order to contact the heating conductor within the housing, having an insulating part (3) which is designed as a sleeve, the sleeve having a central opening through which the electrical conductor (2) is passed, wherein the insulating part (3) has, on the radially outward surface thereof, a first metallization region (4), to which the first metal sleeve (7) is permanently connected, and the insulating part (3) also has, on the radially outward surface thereof, a second metallization region (5), to which the second metal sleeve (8) is permanently connected.

Description

Field of the Invention

[0001] The present invention relates to a device for electrically contacting a heating conductor in an exhaust path, wherein the heating conductor is arranged in a metal housing, and at least one electrical conductor is guided through the housing to contact the heating conductor inside the housing. The device further has an insulating member designed as a sleeve, the sleeve having a central hole through which the electrical conductor is guided. Background Art

[0002] Currently, in order to heat the exhaust gas in the exhaust path downstream of an internal combustion engine or to heat the exhaust gas flowing in the exhaust path, electrical heating elements are often used. The purpose of this is to reach the temperature threshold more quickly, from which the harmful substances carried in the exhaust gas can be effectively converted. This is necessary because the catalytically active surface for exhaust gas aftertreatment of the catalytic (conversion) converter installed in the exhaust path can only sufficiently convert the corresponding harmful substances after reaching the minimum temperature, i.e., the so-called light-off temperature.

[0003] Known solutions in the prior art include so-called heated catalytic converters, which have a metal structure or a ceramic structure with a metal coating connected to a voltage source, and the heated catalytic converter can be heated using ohmic resistance.

[0004] To electrically contact this heatable structure, the electrical conductor must pass through the housing of the exhaust path or through the housing of the catalytic converter arranged in the exhaust path at at least one location. It must be ensured that this penetration is airtight. In addition, electrical insulation must be achieved between the housing and the electrical conductor, and sufficient durability must be ensured. The electrical conductor is usually made of a solid integral material, such as a metal pin.

[0005] German Patent DE 10 2012 110 098 B4 discloses a method for manufacturing an electrical penetration for supplying power to an exhaust gas heating device in a motor vehicle. The penetration has an outer tube, and the electrical conductor passes through the internal space of the outer tube. The electrical conductor extends from the outer tube on at least one end face of the outer tube. The electrical conductor is surrounded by an insulating member in the internal space of the outer tube. The penetration is made from a rod stock that is cut to a fixed length and compacted, wherein the regions serving as the outer tube section and the regions serving as the insulating member section are respectively removed by a machining method, so as to manufacture the electrical penetration with a required length, and the electrical penetration has a predetermined protruding length relative to the outer tube.

[0006] The disadvantages of the methods known in the prior art for manufacturing electrical feed-throughs lie particularly in that the compacted rod stock used is very expensive because this rod stock has a multi-layer structure. In addition, when the electrical conductor is exposed by machining and the electrical feed-through is cut to a specific length, approximately two-thirds of the majority of the material in the rod stock is removed and wasted without being utilized due to the machining. Therefore, the manufacturing process is particularly complex and costly.

[0007] In addition, the known solutions in the prior art usually have poor airtightness and poor moisture resistance. Especially in the case of applications with a 48-volt operating voltage, electrical corrosion also occurs, which has an adverse effect on durability. Summary of the Invention

[0008] Therefore, the object of the present invention is to provide a device that enables better electrical contact / electrical connection of a heating conductor inside a housing and is improved in terms of airtightness and corrosion resistance.

[0009] The object in terms of the device is achieved by a device having the features described in claim 1.

[0010] An embodiment of the present invention relates to a device for electrically contacting a heating conductor in an exhaust path, wherein the heating conductor is arranged inside a metal housing, and at least one electrical conductor passes through the housing to contact the heating conductor inside the housing. The device further has an insulating component designed as a sleeve, the sleeve having a central hole through which the electrical conductor is guided. The insulating component has a first metallized area on its radially outward surface, and a first metal sleeve is permanently connected to the first metallized area. The insulating component also has a second metallized area on its radially outward surface, and a second metal sleeve is permanently connected to the second metallized area.

[0011] The insulating component is preferably formed by a sleeve having a hole extending through it along its axial extension direction. The insulating component thus has an annular cross-section. The hole extends along the central axis of the insulating component, and the insulating component is preferably designed to be rotationally symmetric about its central axis. The axial direction refers to the extension direction along the hole or the central axis, and the radial direction is the direction perpendicular to the central axis.

[0012] The insulating component is preferably made of an electrically insulating material, especially a ceramic material. For example, the insulating component can be formed by sintering or pressing powdered oxide ceramics.

[0013] The size of the hole is preferably designed such that the electrical conductor, which can also be referred to as the inner conductor, can be inserted into the hole with an exact fit. In this regard, it should be particularly noted that the electrical conductor is made of a metal material, preferably made of 2.4869 steel, and thus has different expansion characteristics from the insulating component made of ceramic. Therefore, the size of the hole must be designed such that the expansion of the electrical conductor does not cause damage to the insulating component.

[0014] The metallized region is a region on the outer peripheral part of the insulating component. Preferably, the metallized region is designed to completely surround in the circumferential direction. For example, the insulating component can be metallized by a surface coating, whereby the metallized region obtains the characteristics of a metallic material, and in particular, common connection processes can be used to connect metallic materials to each other.

[0015] The sleeves can be connected to the metallized region, and these sleeves are used to connect the insulating component to the housing of the device and to connect the electrical conductor to the insulating component.

[0016] Particularly advantageously, the first metallized region and the second metallized region are arranged at intervals along the axial extension direction of the insulating component.

[0017] To prevent the formation of an electrically conductive contact between these two sleeves, or between these two equally conductive metallized regions, these two sleeves are preferably arranged at intervals along the axial extension direction of the insulating component. Thus, a creepage distance is formed between these two metallized regions, and this creepage distance is intended to prevent an electrical short circuit between the sleeves or between the metallized regions. The length of this creepage distance depends on the voltage applied to the sleeves. The higher the voltage level, the longer the creepage distance should be designed.

[0018] Equally advantageously, the first metal sleeve forms a connection member / intermediate connection link with the housing of the device. The connection between the insulating component and the housing is achieved through the first metal sleeve. The first metal sleeve is connected to the metallized region on the one hand, for example, by brazing, and to the housing on the other hand, for example, by fusion welding. In principle, all known connection methods for metallic materials can be applied, but it should be noted that the connection between the metal sleeve and the housing should not cause damage to the connection between the metal sleeve and the insulating component, and vice versa. Especially when one of the connections is achieved through a brazing process, the heat load generated by the fusion welding process may cause damage to the brazing connection.

[0019] The size of the metal sleeve is preferably designed such that the metal sleeve can cover a sufficiently large range on the metallized region of the insulating component and at the same time form a sufficiently large contact range with the housing. The radially outer surface of the electrical conductor passing through the insulating component and in principle also through the metal sleeve must have a sufficient spacing from the radially inner surface of the metal sleeve to avoid a short circuit here.

[0020] A preferred embodiment is characterized in that the second metal sleeve constitutes a connection member with the electrical conductor passing through the insulating component.

[0021] The second metal sleeve is abutted against the second metallization region and is preferably also soldered to the second metallization region. The connection between the second metal sleeve and the electrical conductor can then be realized by a fusion welding process. Here, it is also necessary to pay attention to selecting a suitable joining method and performing it in a reasonable and coordinated order to ensure that the connection with poor thermal stability will not be damaged due to the heat input of another connection.

[0022] It is also preferred that the first metal sleeve and / or the second metal sleeve are respectively connected to their respective metallization regions by means of a soldering process.

[0023] Furthermore, it is advantageous that the outer diameter of the insulating component in the region of at least one of the metallization regions is smaller than the outer diameter of the insulating component in the region that separates the two metallization regions from each other.

[0024] The insulating component preferably may have a circumferentially surrounding flange that extends from the axial end of the insulating component to the middle. The region of the creepage distance may in turn have a larger diameter, such that the region of the creepage distance forms a stop for the metal sleeves sleeved from the corresponding end regions, for example. In this way, on the one hand, the positioning of the metal sleeves can be simplified, and on the other hand, the slippage of the metal sleeves or even the contact between the metal sleeves can be effectively avoided. Even if the connection between the metallization region and the metal sleeve is damaged, due to the larger diameter of the insulating component in the region of the creepage distance, the electrical isolation between the two metal sleeves will not be affected.

[0025] It is further advantageous that the insulating component is made of a ceramic material, and the surface of the insulating component in the metallization region is treated to form a metallized surface.

[0026] It is also suitable that the second metallization region and the second metal sleeve are arranged in the housing. Furthermore, it is advantageous that the region of the insulating component that separates the two metallization regions is arranged in the housing.

[0027] In the application of the present invention, the two metallization regions of the insulating component and the soldered sleeves are inserted into the openings in the housing. Subsequently, a permanent and fluid-tight connection is formed between the metal sleeves and the housing. Therefore, the region of the insulating component that faces away from the first metal sleeve and the second metal sleeve must be arranged inside the housing.

[0028] This is particularly advantageous because thereby the untreated region of the insulating component that forms the creepage distance is arranged inside the housing and thus does not withstand corrosive effects, especially those that may come from the environment.

[0029] Advantageous improvements of the present invention are described in the dependent claims and the following description of the drawings. Description of the Drawings

[0030] The present invention will be described in detail below with reference to the accompanying drawings according to embodiments. In the drawings:

[0031] Figure 1 A cross-sectional view of the device according to the present invention is shown. Detailed description of the specific implementation

[0032] Figure 1 The electrical lead-through part 1 is shown, which is composed of an electrical conductor 2 passing through an insulating member 3. The electrical conductor 2 is composed of a metal pin. The insulating member 3 is composed of an annular sleeve having a central hole through which the electrical conductor 2 passes.

[0033] The insulating member 3 has two regions 4, 5, the diameters of which are smaller than the diameter of the region 6 that separates the two regions 4, 5 from each other and forms a creepage distance, and this creepage distance can prevent electrical short circuits between the two regions 4, 5.

[0034] The regions 4, 5 are metallized. Metal sleeves 7, 8 are respectively pushed onto one metallized region 4, 5 each and are permanently connected to their respective metallized regions, for example, by soldering.

[0035] The first metal sleeve 7 connected to the first metallized region 4 is used to connect the electrical lead-through part to a housing (not shown). The second metal sleeve 8 connected to the second metallized region 5 is used to connect to the electrical conductor 2.

[0036] In Figure 1 In the example of, the first metal sleeve 7 is designed as a cylindrical sleeve, and the radially inward surface of the cylindrical sleeve abuts against the first metallized region 4. The housing can be connected, for example, to the radially outward surface of the first metal sleeve 7.

[0037] The second metal sleeve 8 also has a cylindrical section 9 that is connected to the second metallized region. In addition, the metal sleeve 8 has a bent section 10 that bends radially inward and surrounds the electrical conductor 2, so that a connection can be established between the electrical conductor and the second metal sleeve 8.

[0038] The electrical conductor 2 has an end region 11 as follows, and a heating conductor (not shown) can be connected to this end region inside a housing (not shown). In addition, the electrical conductor 2 has a second end region 12 to which a feeder line can be connected.

[0039] In particular, Figure 1 The embodiments of are used to illustrate the inventive concept and are not restrictive.

[0040] List of reference numerals:

[0041] 1 Electrical lead-through part

[0042] 2 Electrical conductor

[0043] 3 Insulating component

[0044] 4 First metallization region

[0045] 5 Second metallization region

[0046] 6 Creepage distance

[0047] 7 First metal bushing

[0048] 8 Second metal bushing

[0049] 9 Cylindrical section

[0050] 10 Bent section

[0051] 11 End region of the electrical conductor

[0052] 12 End region of the electrical conductor

Claims

1. A device for electrically contacting a heating conductor in an exhaust path, wherein, the heating conductor is arranged in a metal housing, and at least one electrical conductor passes through the housing to contact the heating conductor internally. The device has an insulating component (3) designed as a sleeve. The sleeve has a central hole through which the electrical conductor (2) passes. It is characterized in that the insulating component (3) has a first metallized zone (4) on its radially outer surface, and a first metal sleeve (7) is permanently connected to the first metallized zone. The insulating component (3) also has a second metallized zone (5) on its radially outer surface, and a second metal sleeve (8) is permanently connected to the second metallized zone.

2. The device according to claim 1, characterized in that, the first metallized zone (4) and the second metallized zone (5) are arranged spaced apart from each other along the axial extension direction of the insulating component (3).

3. The device according to any one of the above claims, characterized in that, the first metal sleeve (7) forms a connection member with the housing of the device.

4. The device according to any one of the above claims, characterized in that, the second metal sleeve (8) forms a connection member with the electrical conductor (2) passing through the insulating component (3).

5. The device according to any one of the above claims, characterized in that, the first metal sleeve (7) and / or the second metal sleeve (8) is connected to its respective metallized zone (4, 5) by a soldering process.

6. The device according to any one of the above claims, characterized in that, the outer diameter of the insulating component (3) in the region of at least one of the metallized zones (4, 5) is smaller than the outer diameter of the insulating component (3) in the region (6) that separates the two metallized zones (4, 5) from each other.

7. The device according to any one of the above claims, characterized in that, the insulating component (3) is made of a ceramic material. The surface of the insulating component (3) in the region of the metallized zones (4, 5) is treated to form a metallized surface.

8. The device according to any one of the above claims, characterized in that, the second metallized zone (5) and the second metal sleeve (8) are arranged inside the housing.

9. The device according to any one of the above claims, characterized in that, the region (6) of the insulating component (3) that separates the two metallized zones (4, 5) is arranged inside the housing.

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