Media-tight busbar and method for producing a media-tight busbar

Abstract

The invention relates to a busbar (1), in particular for a battery-electric vehicle, comprising a current conductor (2) made of an electrically conductive material and an electrically insulating casing (3). The casing (3) comprises a heat-resistant material and is designed to be media-tight. In addition, a sealing element is arranged between the casing (3) and the current conductor (2), wherein the sealing element is designed as a flexible, heat-shrinkable tube (5) and the flexible, heat-shrinkable tube (5) has at least one adhesive layer (51, 52), or wherein the sealing element is designed as a pre-injection ring, comprising an injection ring (7) and a sealing lip (8). The invention further relates to a production method for providing a busbar (1), in particular a busbar (1) according to the invention.

Description

[0001] W40252W0

[0002] Media-tight busbar and manufacturing process for a media-tight busbar

[0003] The present invention relates to a busbar for electrical applications, in particular for battery-electric vehicles, and to a manufacturing method for such a busbar. The busbar comprises a conductor made of electrically conductive material and an electrically insulating sheath to ensure media tightness of the busbar, in particular against oil, such as thermal oil, for cooling electrical components such as high-voltage batteries, electric motors and power electronics, as well as transmission oil.

[0004] In the field of electrical power transmission and distribution, particularly in battery-electric vehicles, it is common practice to use busbars for transmitting high electrical power. Modern battery-electric vehicles incorporate numerous busbars. Innovative vehicle concepts increasingly rely on thermal management via immersion cooling, where electric motors and power electronics are cooled directly with oil, either by spraying or immersion. In this process, busbars come into contact with this oil, especially thermal oil, but also water and / or glycol. Furthermore, it is essential to prevent oil from leaking into the engine compartment. This will place increased demands on the media tightness of these busbars in the future. Another challenge for busbars in this environment is the exposure to vibrations and rapid temperature changes caused by charging currents.The busbars must therefore also be suitable for loads caused by temperature changes and vibrations.

[0005] Currently, rectangular busbars are manufactured by stamping out conductors from copper or aluminum sheets and then bending them into the desired dimensions. Due to the nature of this process, the corners of the resulting cross-section are unsuitable for creating a seal against any encapsulation. Common methods for applying an encapsulation do not provide a satisfactory seal and often require complex post-processing.

[0006] CN 203931 553 U describes a round conductor surrounded by several insulating and shielding layers. CN 1 03137251 A proposes sheathing a conductor using a ceramic-silicone rubber and heat-shrink tubing. DE 102013212166 A1 relates to a conductor arrangement comprising a conductor element, an insulating element, and a sealing element, wherein the conductor element has a positive-locking area that provides a positive connection between the conductor element and the insulating element, thus reducing the difference in absolute linear expansion between the conductor element and the insulating element, particularly with respect to the sealing element, compared to a difference without a positive-locking area. WO 2008 / 141 629 A1 discloses a lamp base for an electric lamp.

[0007] The object of the present invention is to overcome at least some of the disadvantages of the prior art, in particular to provide a media-tight busbar and a corresponding manufacturing process, so that gap formation between the conductor and the sheathing can be reduced and sealing can be improved over the lifetime of the busbar under the given conditions.

[0008] This problem is solved by a busbar having the features of claim 1. Dependent claim 24 relates to a corresponding manufacturing method for a busbar. Advantageous embodiments of the invention are the subject of the dependent claims.

[0009] Accordingly, a busbar, particularly for a battery-electric vehicle, is provided, comprising a conductor made of an electrically conductive material and an electrically insulating sheath. The sheath comprises a heat-resistant material and is media-tight.

[0010] The term busbar refers to a component that carries electrical energy from a source to various consumers or to other distribution points. In this context, the busbar may be specifically designed for battery electric vehicles, meaning it is capable of meeting the requirements and conditions of such vehicles.

[0011] The conductor, made of an electrically conductive material, serves to efficiently transport electric current. Electrically conductive materials are typically metals such as copper or aluminum, chosen for their high conductivity. The electrically insulating sheath protects the conductor from external influences and simultaneously ensures that the electric current is not unintentionally conducted to other parts of the vehicle or to people.

[0012] Because the sheathing is designed to be media-tight, the invention enables the electrical conductor to be sealed, particularly against thermal oil or gear oil. The media-tight design of the sheathing can be achieved, for example, by the sheathing itself having a sealing function and / or by the sheathing comprising a further element, in particular a sealing element, which fulfills a sealing function and is arranged between the sheathing and the electrical conductor.

[0013] Because the sheathing is heat-resistant, the invention prevents separation of the sheathing from the conductor at high temperatures, or at least reduces the likelihood of such separation. The increased heat resistance of the sheathing thus leads to a reduction in gap formation, even under particularly strong temperature fluctuations. Preferably, the sheathing material can have low thermal conductivity to reduce heat transfer to adjacent components.

[0014] Preferably, the conductor comprises a material with high electrical conductivity. For example, the conductor may preferably be made of copper, aluminum, copper foam, or aluminum foam. The conductor forms the central element of the busbar and is crucial for the efficient transmission of electrical energy, especially in battery-electric vehicles, where high currents must be conducted safely and effectively. Copper and aluminum are known for their excellent electrical conductivity, which means they minimize electrical resistance and thus reduce energy losses during transmission. This is particularly advantageous in applications where energy efficiency and heat generation are critical factors. Copper foam and aluminum foam also offer the advantage of an increased surface area, which improves heat dissipation and thus increases the thermal stability of the busbar.

[0015] According to further training, the busbar encasing comprises a thermoplastic material, ceramic, and / or fiberglass. The thermoplastic material offers the advantage of high flexibility and ease of processing, which facilitates the manufacturing and adaptation of the busbar to various shapes and sizes. Thermoplastic materials are characterized by their ability to become malleable when heated and retain their shape after cooling, enabling efficient and cost-effective production. Ceramic, as a component of the encasing, provides excellent thermal stability and electrical insulation, which is particularly important for ensuring the safety and reliability of the busbar in high-temperature environments. Ceramic materials are also non-combustible and resistant to chemical influences, which increases the busbar's service life.Fiberglass contributes to the mechanical strength and stability of the sheathing by improving the structural integrity of the busbar while reducing its weight.

[0016] Fiberglass-reinforced encapsulations are known for their high tensile strength and resistance to mechanical stress, making the busbar more resistant to physical impacts. The combination of these materials in the encapsulation results in a busbar that is both thermally and mechanically robust while also providing excellent electrical insulation.

[0017] Preferably, the thermoplastic polymer contains the highest possible proportion of glass fibers to achieve lower thermal expansion. Alternatively or additionally, the polymer may contain a halogen-free flame retardant. In particular, the polymer may comprise polyketone, polyphthalamide (PPA), and / or polyamide. Polyketone is electrically insulating and exhibits high elongation at break, low water absorption, and high impact strength. PPA is also electrically insulating and exhibits low thermal expansion and low shrinkage. The latter allows for advantageous processability. PA66 is also electrically insulating with high elongation at break.

[0018] According to one embodiment, the busbar has a material-bonded, media-tight connection between the conductor and the sheathing, wherein this connection particularly comprises a metal and a ceramic and / or polymeric material. The material-bonded connection enables the invention to achieve a stronger bond between the conductor and the sheathing.

[0019] A metallurgical bond is a connection in which the materials are bonded together at the molecular level, creating a particularly strong and durable bond. This type of bond can be achieved through various processes, such as welding, soldering, gluing, or chemical bonding, with the choice of process depending on the specific materials and the application requirements. A chemical bonding process, for example, may involve the use of an adhesion promoter.

[0020] The use of a metal in the bonded connection offers the advantage of high mechanical strength. The ceramic material in the cladding provides excellent heat resistance and electrical insulation, which is particularly important for ensuring the safety and reliability of the busbar in a battery-electric vehicle. A polymer material can also be used to provide flexibility and additional insulation, increasing the busbar's adaptability to different installation locations and operating conditions. Combining these materials in a bonded connection makes it possible to leverage the advantages of each material while minimizing their respective disadvantages. For example, the ceramic cladding can increase heat resistance, while the polymer-based material improves flexibility and electrical insulation.

[0021] The material bond can be provided by an additional layer between the conductor and the sheathing, or alternatively, the material bond can be provided by the conductor and the sheathing themselves. A direct material bond between the conductor and the sheathing can thus be achieved, for example, through the application of heat.

[0022] Preferably, the conductor has at least one groove. The groove depth is particularly greater than the gap that would form between the sheath and the conductor due to thermal expansion, thus improving the sealing effect of the sheath. Preferably, the conductor has several, particularly parallel, grooves. Most preferably, the grooves form a labyrinth geometry. The at least one groove provides a positive-locking, media-tight connection between the conductor and the sheath, further reducing gap formation between the conductor and the sheath, as the groove compensates for gap formation during temperature changes.

[0023] According to a further development, the busbar comprises a sheath with an inner layer and an outer layer, wherein the inner layer is in contact with the conductor and has a higher coefficient of thermal expansion than the outer layer. This means that the inner layer expands and contracts more than the outer layer with temperature changes. When the temperature increases, the inner layer expands more than the outer layer and is compressed between the conductor and the outer layer. Any resulting gap between the outer layer and the conductor can thus be filled by the inner layer. Preferably, the inner layer comprises silicone and the outer layer a thermoplastic such as polyketone, particularly in combination with glass fiber.

[0024] The invention allows the inner layer to be in contact with the conductor and the groove. This enables the inner layer to be compressed between the groove and the outer layer, further reducing gaps between the conductor and the sheathing. In particular, the outer layer can completely surround the inner layer, shielding it from the surrounding environment. Alternatively or additionally, the inner layer can completely cover and / or fill the at least one groove.

[0025] The inner layer of the casing can also incorporate a sealing element, or a sealing element can form the inner layer. For example, the inner layer can be formed by or include a heat-shrinkable tube, a potting compound, and / or a pre-molded ring. This allows the invention to advantageously design the inner layer for specific applications.

[0026] Preferably, the busbar includes a sealing element arranged between the electrically insulating sheath and the conductor. The sealing element can, for example, be designed as a flexible, heat-shrinkable tube, a so-called heat-shrink tubing. The material of the sealing element is preferably ethylene-vinyl acetate (EVA). Preferably, the sealing element is elastic so that it can compensate for temperature-related dimensional changes of the conductor and / or the sheath.

[0027] According to a further development, the sealing element is designed to provide a connection with the conductor and / or the sheathing, in particular by having at least one adhesive layer. This results in improved adhesion between the conductor and the sealing element and / or the sealing element and the sheathing.

[0028] The sealing element preferably has an internal adhesive layer facing the conductor, through which adhesion to the conductor is established. When the sealing element is designed as a flexible, heat-shrinkable tube, the connection between the conductor and the sealing element can thus be improved compared to compression alone. In particular, a more extensive bond with reduced bubble formation can be achieved. The internal adhesive layer preferably comprises an adhesive consisting of polyamide.

[0029] Preferably, the sealing element can alternatively or additionally have an outer adhesive layer facing the sheathing, which establishes adhesion to the sheathing. The outer adhesive layer can, in particular, comprise a heat-activated material, especially a hot-melt adhesive, whose adhesive properties can be activated by heat. Particularly preferably, the outer adhesive layer comprises an EVA (ethylene-vinyl acetate) material with good adhesive properties. Alternatively, the adhesive properties can also be activated by inductive energy input. According to a further embodiment, the sealing element is designed as a potting compound. The potting compound can comprise a potting compound and / or a sealant. The potting compound establishes adhesion to the conductor and the sheathing and compensates for geometric changes due to temperature fluctuations between the conductor and the sheathing.This prevents or at least reduces the formation of gaps between the conductor and the sheathing. The potting compound preferably consists of polyacrylate or silicone. Curing of the potting compound can be achieved, for example, using a two-component adhesive or UV irradiation.

[0030] According to further training, the busbar includes a recess located between the conductor and the sheathing to accommodate the sealing element. This recess allows for precise positioning of the sealing element, making busbar manufacturing more efficient. This is particularly important when the sealing element is potted, as it reduces material waste and lowers production costs.

[0031] Alternatively or additionally, the sealing element can be designed as a pre-molded ring. The pre-molded ring comprises a molded ring and a sealing lip. Designing the sealing element as a pre-molded ring allows for advantageous sealing of the conductor. The molded ring can be made of the same material as the sheathing. The sealing lip preferably comprises liquid silicone rubber (LSR). The sealing lip can be provided, in particular, by overmolding the molded ring. Most preferably, the sealing lip surrounds the molded ring over its entire circumference and / or is located on a surface of the molded ring facing the conductor.

[0032] In particular, the injection-molded ring can be arranged on the conductor such that the sealing lip is mechanically pressed against the conductor. This enhances the sealing effect. Preferably, the injection-molded ring is connected to the sheathing by overmolding. Furthermore, the injection-molded ring is preferably designed with at least one melting rib, which can contribute to an improved sealing effect between the injection-molded ring and the sheathing. The at least one melting rib can be provided by melting it onto the injection-molded ring, particularly when sheathing the conductor. The thickness of the at least one melting rib can be, for example, between 0.05 and 0.3 mm, preferably between 0.1 and 0.25 mm, and most preferably between 0.1 and 0.2 mm.

[0033] In one embodiment, an outer surface of the casing has a structure and / or coating. This structure and / or coating enables improved heat dissipation by convection. A possible structure could, for example, be in the form of grooves, raised areas, or other geometric patterns. Such a structured surface can improve heat dissipation by increasing the surface area and thus facilitating heat dissipation by convection or radiation. The coating can be designed to compensate for unequal thermal expansion and ensure a tight seal.

[0034] Alternatively or additionally, the surface of the conductor may have a textured surface. This allows the busbar to provide a better seal between the conductor and the sheathing. The textured surface can, for example, be a profile on the conductor. The profile can be regular or irregular, such as exhibiting a pattern, particularly a geometric one, at least in certain areas. The profile can be formed as a raised area and / or a depression in or on the conductor.

[0035] According to a further development, the geometry of the conductor, in particular its outer radius, can be designed such that the connection between the conductor and the sheathing remains leak-proof even under extreme thermal stress. Thus, the outer radius of the conductor, i.e., the edge rounding, is preferably between 0.25 and 1 mm, and particularly preferably between 0.75 and 0.85 mm.

[0036] Furthermore, the busbar can have a cooling system and / or be connected to one to dissipate heat generated within it. This cooling system can include a cooling gas channel running along the conductor. The cooling gas channel can be formed by making the busbar, particularly the conductor, hollow. Air can be used as the cooling gas. Alternatively or additionally, the cooling system can include a pelletizer element for active cooling, which is, for example, integrated into the busbar.

[0037] The conductor can also consist of multiple strands combined with different materials to ensure optimized heat and current conduction. Alternatively or additionally, the sheathing can be equipped with a bimetallic strip to trigger a protective function in case of overheating. Furthermore, the busbar can incorporate a coil structure to suppress electromagnetic interference. The busbar can also function as a capacitor to dampen voltage spikes in the current flow.

[0038] According to further training, the casing can incorporate miniaturized components. These miniaturized components can be made of thermally conductive materials to improve heat dissipation. Furthermore, the miniaturized components can be arranged in thin layers within the casing. This miniaturization allows for a space-saving design. The miniaturized components can be manufactured, for example, using microfabrication techniques such as laser sintering or micromilling.

[0039] Furthermore, the casing can include electromagnetic shielding. This shielding can consist of conductive fabric and / or conductive film that absorbs interference in the high-frequency range. Simulation-based optimization can be used to maximize efficiency.

[0040] According to one embodiment, the busbar can be combined with another busbar. For this purpose, the busbar can have a connector and the other busbar a corresponding mating connector. The other busbar can be designed according to one of the embodiments of the busbar according to the invention.

[0041] In particular, the additional busbar can have a cooling system and / or be connected to a cooling system. According to a second aspect of the invention, a manufacturing method for providing a busbar, especially one according to the invention, particularly for battery-electric vehicles, is provided. The manufacturing method comprises the steps of providing a conductor made of an electrically conductive material and encasing the conductor in a media-tight manner with a heat-resistant material. An advantage of this method lies in the improved thermal stability of the busbar, which is achieved by using materials that can withstand high temperatures, such as special plastics or ceramics. In particular, this can prevent or at least reduce the formation of gaps between the conductor and the encasing, so that the manufactured busbar is media-tight.

[0042] The encapsulation is preferably achieved by overmolding the conductor with the heat-resistant material. Overmolding, as a specific encapsulation technique, enables a precise and uniform distribution of the insulating material around the conductor, resulting in a homogeneous protective layer. This technique also offers the advantage of high production speed and efficiency, as it can be integrated into automated processes.

[0043] According to further training, the encapsulation process involves a two-step application. The first step involves applying an inner layer, and the second step involves applying an outer layer. The material of the inner layer has a higher coefficient of thermal expansion than the material of the outer layer. Positioned between the outer layer and the conductor, the inner layer, due to its greater expansion during temperature increases, is compressed between the conductor and the outer layer, thus compensating for any gap that may form between them. This two-step application process therefore results in improved media tightness of the manufactured busbar. The application of the inner layer may involve the use of an adhesion promoter.

[0044] Preferably, the manufacturing process comprises arranging a sealing element between the conductor and a sheath produced or to be produced during the sheathing process. Prior to sheathing, this arrangement may include mounting a sealing element, designed as a flexible, heat-shrinkable tube, onto the conductor. The flexible, heat-shrinkable tube can improve the media tightness of the manufactured busbar because, when heated, it contracts to conform tightly to the conductor, thus protecting it from contact with the medium. Furthermore, the flexible, heat-shrinkable tube may be designed to improve adhesion between the conductor and the sheath.

[0045] The installation of the flexible, heat-shrinkable tubing may involve positioning the conductor within an installation aid. This aid can, in particular, act as a stop for the flexible, heat-shrinkable tubing. Thus, the flexible, heat-shrinkable tubing may be pushed onto the conductor during installation until it makes contact with the installation aid. The installation aid therefore ensures precise positioning of the flexible, heat-shrinkable tubing on the conductor.

[0046] Preferably, the flexible, heat-shrinkable tubing has an internal adhesive layer that contacts the conductor. This adhesive layer can be activated in a further process step between assembling the flexible, heat-shrinkable tubing and applying the outer sheath. Activation can involve heating the flexible, heat-shrinkable tubing so that it shrinks onto the conductor. The internal adhesive layer then bonds the flexible, heat-shrinkable tubing and the conductor. Heating is preferably carried out at a temperature between 120 and 350 °C. More preferably, the heating process lasts between 1 and 2 seconds.

[0047] After activating the internal adhesive layer, the busbar can be removed from the assembly aid and inserted into an injection mold. A visual inspection of the insert, for example using a camera, can be performed during this process or even before insertion to verify the correct installation of the flexible, heat-shrinkable tubing. The busbar is then encased in the tubing within the injection mold.

[0048] Preferably, the flexible, heat-shrinkable tubing can alternatively or additionally have an external adhesive layer that contacts the outer sheath. This external adhesive layer can be activated by heat, for example, by using a hot melt adhesive. In particular, the external adhesive layer can be designed so that its adhesive effect is activated by the heat applied during the sheathing process, forming a bond with the sheath. This provides a strong, bonded connection between the flexible, heat-shrinkable tubing and the sheathing. Because the activation of the external adhesive layer occurs during the sheathing process, no additional process step is required.

[0049] According to further training, the arrangement of the sealing element can include applying a sealing element designed as a potting compound between the sheathing and the conductor. The potting compound thus provides adhesion between the conductor and the sheathing. This subsequent application of the potting compound can, in particular, fill gaps between the conductor and the sheathing that arise due to manufacturing tolerances and / or other deviations, for example, during the sheathing process.

[0050] The application process can be carried out in several steps. The sheathed conductor can be inserted into a dispensing machine. The actual application of the potting compound can then take place in the dispensing machine. For this purpose, a recess can be created between the conductor and the sheathing during the encasing process. A precisely measured amount of potting compound or sealant can then be injected into this recess using the dispensing machine. After application, the potting compound can be left to cure.

[0051] Curing, particularly for single-component potting compounds, can be achieved by UV irradiation. For this purpose, the busbar is preferably irradiated for 20 to 30 seconds. Particularly preferably, the busbar then dries for a further 72 hours. Alternatively or additionally, curing, particularly for multi-component potting compounds, can occur naturally over a longer period. In this case, the self-curing period is at least 6 minutes for a touch-dry surface, but preferably at least 15 minutes before the busbar is removed. Particularly preferably, the busbar cures naturally for a total of 7 days.

[0052] Preferably, the curing process includes a visual inspection, for example by camera, of the busbar. This visual inspection can be performed after curing, before curing, and / or during curing. In particular, it may be provided that the visual inspection is performed repeatedly.

[0053] It is also possible that the process prior to encapsulation includes mounting a sealing element, designed as an injection-molded ring, onto the conductor, wherein the injection-molded ring has a sealing lip. The injection-molded ring and sealing lip then form a pre-injection ring, which enables improved sealing of the conductor. The injection-molded ring can be made of the same material as the encapsulation. The sealing lip preferably comprises liquid silicone rubber (LSR). The sealing lip can be provided, in particular, by overmolding the injection-molded ring. Particularly preferably, the sealing lip surrounds the injection-molded ring over its entire circumference and / or the injection-molded ring is mounted on the conductor such that the sealing lip faces the conductor. In particular, the injection-molded ring is mounted on the conductor in such a way that the sealing lip is mechanically pressed against the conductor. This enhances the sealing effect.

[0054] When encasing the conductor, the injection-molded ring can be joined to the sheath, particularly by overmolding. Furthermore, especially during the sheathing process, at least one fused-to-metal seal can be melted onto the injection-molded ring. This allows for an improved seal between the injection-molded ring and the sheath. The at least one fused-to-metal seal is located, in particular, on a surface of the injection-molded ring facing the sheath. The thickness of the at least one fused-to-metal seal can be, for example, between 0.05 and 0.3 mm, preferably between 0.1 and 0.25 mm, and most preferably between 0.1 and 0.2 mm.

[0055] The manufacturing process according to the invention is particularly suitable for manufacturing a busbar according to the invention. The details and advantages disclosed for the busbar according to the invention are transferable and applicable to the manufacturing process according to the invention, and vice versa. Further details of the invention are explained with reference to the following figure. This figure shows:

[0056] Figure 1 shows an embodiment of a busbar according to the invention with several conductors and an electrically insulating, media-tight sheathing;

[0057] Figure 2 shows a schematic representation of a manufacturing process according to the invention, in which a current conductor with grooves is overmolded with a sheathing;

[0058] Figure 3 shows a schematic representation of a manufacturing process according to the invention, in which a conductor with a groove having a sheathing is overmolded with an inner layer and an outer layer;

[0059] Figure 4 shows a schematic representation of a busbar according to the invention with a 1-component sheathing with and without a groove under changing temperature conditions;

[0060] Figure 5 shows a schematic representation of a busbar according to the invention with a 2-component sheathing with and without a groove under changing temperature conditions;

[0061] Figure 6 shows an embodiment of a busbar according to the invention with a flexible, heat-shrinkable tube arranged between the conductor and the sheathing in a perspective view and a sectional view;

[0062] Figure 7 is a schematic representation of a manufacturing process according to the invention, in which a conductor is first fitted with a flexible, heat-shrinkable tube and then sheathed; Figure 8 is an embodiment of a busbar according to the invention with a casting resin encapsulation in a sectional view; and

[0063] Figure 9 shows a schematic representation of a manufacturing process according to the invention, in which a busbar receives a casting resin encapsulation after being encased; and

[0064] Figure 10 shows an embodiment of a busbar according to the invention with a pre-molded ring arranged between the conductor and the sheathing in a sectional view.

[0065] Figure 1 shows an embodiment of a busbar 1, which is designed in particular for a battery-electric vehicle. The busbar 1 comprises three conductors 2 and a sheath 3. The conductors 2 are made of an electrically conductive material, in particular copper or copper foam, to achieve the highest possible electrical conductivity.

[0066] Since the busbar 1 is to be designed to be media-tight, especially against oil, such as thermal oil, but also against water and / or glycol, for cooling electrical components such as high-voltage batteries, electric motors and power electronics as well as gear oil, the sheathing 3 is provided here, which is electrically insulating, heat-resistant and sealing.

[0067] Because the sheathing 3 is heat-resistant, the adhesion between the conductors 2 and the sheathing 3 can be improved. A challenge regarding the media tightness of busbars 1 is posed by the different coefficients of thermal expansion of the conductors 2 and the sheathing 3. This can lead to gaps forming between the conductors 2 and the sheathing 3, creating creepage distances that compromise the insulation of the conductors 2 from the surrounding medium. A heat-resistant sheathing 3, however, can prevent or at least reduce the different expansion behavior between the conductors 2 and the sheathing 3, thereby preventing or at least reducing gap formation. The material of the sheathing 3 can include, in particular, a thermoplastic polymer, ceramic, and / or glass fiber.Suitable thermoplastic polymers include polyketone, polyphthalamide (PPA), and / or polyamide. A particularly preferred material choice is a glass fiber-reinforced polyketone. To further increase the adhesion between the conductor 2 and the sheath 3, a metallurgical bond can be provided, in particular a metallurgical bond between a metal and a ceramic and / or polymeric material.

[0068] To increase heat dissipation, particularly by convection, from the busbar 1, the embodiment shown in Fig. 1 provides structuring 33 in the form of protrusions on the outer surface of the casing 3. The increased surface area facilitates heat dissipation. Alternatively or additionally, the outer surface of the casing 3 can be coated to promote heat dissipation.

[0069] Figure 2 schematically shows an embodiment of a manufacturing process for a media-tight busbar 1. The manufacturing process comprises two steps. In a first step S100, a conductor 2, here a copper busbar, having 3 slots 21, is provided and inserted into a mold. In the second step S200, the insert 2 is then overmolded with the media-tight encapsulation in the mold, so that a busbar 1 is produced which comprises a conductor 2 with an electrically insulating encapsulation 3. The slots 21, which can also be designed as a labyrinth geometry, reduce and / or prevent gap formation due to temperature changes between the conductor 2 and the encapsulation 3.

[0070] Figure 3 schematically shows another embodiment of a manufacturing process for a media-tight busbar 1. This manufacturing process comprises three steps. In a first step S100, a conductor 2, here a copper busbar, is provided with a groove 21 and inserted into a mold. In the mold, the insert 2 is first overmolded with an inner layer 31 in step S210, before being overmolded with an outer layer 32 in a further step S220. The inner layer 31 is applied in the area of ​​the groove 21. Thus, at the end of the manufacturing process, a busbar 1 is available, comprising a conductor 2 and a sheath 3, the sheath 3 having an inner layer 31 and an outer layer 32.

[0071] The inner layer 31 has a higher coefficient of thermal expansion than the outer layer 32. In this case, the inner layer 31 is made of silicone, while the outer layer 32 is made of plastic, preferably glass fiber reinforced polyketone. Such a busbar 1 is advantageous with regard to media tightness because the higher coefficient of thermal expansion of the inner layer 31 causes the material of the inner layer 31 to be compressed between the outer layer 32 and the conductor 2 when the temperature changes, for example, when heated. Thus, any gap that may form between the conductor 31 and the outer layer 32 can be at least partially compensated for by the inner layer 31. This increases the tightness of the busbar 1.

[0072] Figure 4 schematically illustrates the influence of a groove 21 in a conductor 2 on the media tightness of a busbar 1. The lower part of the figure shows a busbar 2 without a groove 21, while the upper part shows a busbar 2 with a groove 21. Furthermore, both busbars 1 are depicted in three different states. On the far left, the busbars 1 are in an initial state, specifically at room temperature of approximately 23 °C. In this state, there can be no gap between the sheathing 3 and the conductor 2.

[0073] The busbars 1 are shown in the center at an elevated temperature, specifically approximately 180 °C. It can be seen that the conductor 2, for example, made of copper, expands slightly compared to its initial state, while the plastic of the sheathing 3 expands considerably. As a result, a gap 4 forms, at least in some areas, between the conductor 2 and the sheathing 3. The diagram on the far right shows the busbars 1 undergoing rapid cooling from approximately 180 °C. Due to its lower heat capacity, the copper of the conductor 2 cools down, while the plastic of the sheathing 3 remains warm for longer. Overall, it can be seen that the resulting gap 4 between the conductor 2 and the sheathing 3 is significantly smaller with a groove 21 than without such a groove 21. This is primarily because the effect of the different coefficients of thermal expansion is less pronounced within the groove 21.In particular, a gap 4, as shown in Fig. 4, can be reduced by up to 98% with the groove 21. The media tightness of the busbar 1 can thus be significantly increased with the groove 21.

[0074] Figure 5 schematically illustrates the influence of the inner layer 31 of a sheath 3 on the media tightness of a busbar 1. Similar to the representations in Figure 4, Figure 5 shows an initial state on the left. In the center, the busbar 1 is shown at an elevated temperature, for example, 180 °C. While in the initial state there is no gap between the sheath 3 and the conductor 2, the temperature increase and the different coefficients of thermal expansion of the copper of the conductor 2 and the plastic of the outer layer 32 result in a gap 4. The silicone of the inner layer 31, which has a higher coefficient of thermal expansion, expands more than the plastic of the outer layer 32 and, due to its geometry, can only compress towards the conductor 2. The gap 4 is thus at least partially occupied by the inner layer 31.Such a busbar 1 with a two-component sheathing 3 thus exhibits improved media tightness.

[0075] In the illustration on the right, the 2-component busbar 1 is also shown with a groove 21. The groove 21 further improves the media tightness, as gap formation between the conductor 2 and the outer layer 32 of the sheathing 3 can be practically completely avoided.

[0076] Figure 6 schematically shows another embodiment of a busbar 1 according to the invention. The busbar 1 is shown in a perspective view in the lower illustration and in a sectional view in the upper illustration. This busbar 1 also has a conductor 2 and a sheath 3. However, a sealing element designed as a flexible, heat-shrinkable tube 5 is additionally arranged between the conductor 2 and the sheath 3. The flexible, heat-shrinkable tube 5 shrinks when heated, causing it to fit snugly against the conductor 2 and form a tight seal. The flexible, heat-shrinkable tube 5 can also be elastic and thus compensate for temperature-related dimensional changes of the sheath 3 and / or the conductor 2. Here, the flexible, heat-shrinkable tube 5 has an inner adhesive layer 51 and an outer adhesive layer 52.

[0077] The internal adhesive layer 51 can be provided to create adhesion between the flexible, heat-shrinkable hose 5 and the electrical conductor 2. The internal adhesive layer 51 can, in particular, comprise a polyamide adhesive, for example, a polyamide-R adhesive.

[0078] The outer adhesive layer 52 can be provided to create adhesion between the flexible, heat-shrinkable tubing 5 and the sheathing 3. The outer adhesive layer 52 can, in particular, comprise a heat-activated material, such as an EVA material with good adhesive properties. Thus, the adhesive properties of the outer adhesive layer 52 can be activated, for example, during the overmolding of the conductor 2 with the sheathing 3, eliminating the need for an additional process step to bond the flexible, heat-shrinkable tubing 5 to the sheathing 3.

[0079] Figure 7 schematically shows an embodiment of a manufacturing process according to the invention, in particular for a busbar 1 shown in Figure 6. The manufacturing process comprises five steps. In a first step S100, a conductor 2 is provided and inserted into an assembly aid 54. In the following step S110, a sealing element is arranged between the conductor 2 and a sheathing 3 to be produced during a sheathing process S200 by mounting the sealing element, designed as a flexible, heat-shrinkable tube 5, onto the conductor 2, with the assembly aid 54 serving as a stop. In step S130, the flexible, heat-shrinkable tube 5 is selectively heated by means of a heat source 53, so that the flexible, heat-shrinkable tube 5 shrinks onto the conductor 2.The heat source 53 heats the flexible, heat-shrinkable tubing 5, preferably for 1 to 2 seconds, to a temperature in the range of 120 to 350 °C. An internal adhesive layer 51 of the flexible, heat-shrinkable tubing 5 additionally bonds the conductor 2 and the flexible, heat-shrinkable tubing 5. In step S140, the conductor 2 is removed from the assembly aid 54 and inserted as an insert into a tool, in particular an injection mold. A visual inspection of the insert 2, for example by camera, can also be performed to verify that the flexible, heat-shrinkable tubing 5 is correctly positioned against the conductor 2. In the final step S200, the conductor 2 is overmolded with the sheathing 3.The heat applied during overmolding activates an outer adhesive layer 52 of the flexible, heat-shrinkable tubing 5, causing it to bond with the sheathing 3. This manufacturing process thus provides a busbar 1 that exhibits advantageous adhesion between the flexible, heat-shrinkable tubing 5 and the conductor 2 on the one hand, and between the flexible, heat-shrinkable tubing 5 and the sheathing 3 on the other. This results in increased media tightness of the busbar 2.

[0080] Figure 8 schematically shows another embodiment of a busbar 1 according to the invention, which has a sealing element made of casting resin 6, in particular epoxy resin, arranged between the sheath 3 and the conductor 2. In particular, a recess 61 is provided in the sheath 3 in which the casting resin 6 is arranged. The casting resin 6 compensates for geometric changes during temperature fluctuations between the sheath 3 and the conductor 2, so that the busbar 1 exhibits increased media tightness, as gap formation is reduced. The casting resin 6 can, in particular, be based on polyacrylate or silicone.

[0081] Figure 9 schematically shows an embodiment of a manufacturing process according to the invention, in particular for a busbar 1 as shown in Figure 8. In a first step S100, a conductor 2 is inserted into a mold as an insert. In step S200, the insert 2 is overmolded with a coating 3 in the mold. During this overmolding process, a recess 61 is formed in the coating 3. In step S310, the busbar 1 is removed from the mold and transferred to a metering machine.

[0082] In step S320 of the dosing machine, a sealing element designed as a potting compound is applied by injecting a precisely metered amount of casting resin 6 into the recess 61 formed in the casing 3. In step S330, the casting resin 6 is then cured by means of an irradiation source 62, which provides UV light. In the final step S340, the busbar 1 is stored until the casting resin 6 has sufficiently cured. In steps S330 and S340, an additional optical inspection, for example using a camera, of the busbar 1, and in particular of the casting resin 6, can be performed to determine the degree of curing of the casting resin 6 and to adjust the duration of the irradiation and / or storage accordingly.

[0083] The curing process of steps S330 and S340 can be adapted to the composition of the casting resin 6. For example, in the case of a single-component casting resin 6, curing according to step S330 can be carried out using an irradiation source 62, in particular UV irradiation. The irradiation can be performed for approximately 20-30 seconds. Afterwards, further curing can be carried out by storage according to step S340. This storage can last for approximately 72 hours.

[0084] For a casting resin comprising two or more components, curing can occur spontaneously, particularly through storage according to step S330 and without irradiation according to step S340. The storage time can be extended accordingly. For example, busbar 1 can be allowed to dry for approximately 6 minutes, perhaps while still in the dispensing machine, until its surface is touch-dry. It can then be stored without settling for approximately 15 minutes. Finally, the busbar can be stored for a further approximately 7 days until it is fully cured.

[0085] Figure 10 schematically shows another embodiment of a busbar 1 according to the invention. The busbar 1 is shown in a sectional view. This busbar 1 also has a conductor 2 and a sheathing 3.

[0086] Between the conductor 2 and the sheathing 3, an additional sealing element designed as a pre-molded ring is arranged, comprising a molded ring 7 and a sealing lip 8. The molded ring 7 can be mounted on the conductor 2, in particular, before the conductor 2 is sheathed S200.

[0087] The injection ring 7 is made of the same material as the sheath 3. The sealing lip 8 comprises liquid silicone rubber (LSR). The sealing lip 8 is formed by overmolding the injection ring 7, so that the injection ring 7 fully incorporates the sealing lip 8 on an inner surface. The injection ring 7 is mounted on the conductor 2 such that the sealing lip 8 faces the conductor 2. In particular, the injection ring 7 can be positioned on the conductor 2 such that the sealing lip 8 is mechanically pressed against the conductor 2. This enhances the sealing effect.

[0088] The injection molding ring 7 shown was connected to the sheathing 3 during the sheathing process S200 of the conductor 2, for example by overmolding. To increase the sealing effect between injection molding ring 7 and sheathing 3, the injection molding ring 7 has two melting ribs 9 arranged on one of its surfaces facing the sheathing 3. These two melting ribs 9 can be applied to the injection molding ring 7, for example by melting, particularly during the sheathing process S200. The thickness of the two melting ribs 9 is approximately 0.15 mm.

[0089] The features of the invention disclosed in the foregoing description, in the drawings, and in the claims can be essential for the realization of the invention, both individually and in any combination. Reference numeral list

[0090] busbar

[0091] electrical conductors

[0092] sheathing

[0093] gap

[0094] Flexible, heat-shrinkable tubing (heat shrink tubing) Casting resin

[0095] Splash ring

[0096] Sealing lip

[0097] Enamel rib

[0098] Nut

[0099] Inner layer

[0100] Outer layer

[0101] structuring

[0102] Internal adhesive layer

[0103] External adhesive layer

[0104] heat source

[0105] Assembly aid

[0106] in-depth

[0107] radiation source

Claims

Claims:

1. Busbar (1), in particular for a battery electric vehicle, comprising a conductor (2) made of an electrically conductive material and an electrically insulating sheath (3), wherein the sheath (3) comprises a heat-resistant material and is media-tight, wherein a sealing element is arranged between the sheath (3) and the conductor (2) and wherein the sealing element is designed as a flexible, heat-shrinkable tube (5), wherein the flexible, heat-shrinkable tube (5) has at least one adhesive layer (51, 52); or the sealing element is designed as a pre-injection ring, comprising an injection ring (7) and a sealing lip (8).

2. Busbar (1) according to claim 1, wherein the conductor (2) comprises a material with high electrical conductivity, preferably copper, aluminum, copper foam or aluminum foam.

3. Busbar (1) according to claim 1 or 2, wherein the sheathing (3) comprises a thermoplastic polymer, ceramic and / or glass fiber.

4. Busbar (1) according to one of the preceding claims, comprising a material-bonded, media-tight connection between the conductor (2) and the sheathing (3), in particular a material-bonded, media-tight connection made of a metal and a ceramic and / or polymeric material.

5. Busbar (1) according to one of the preceding claims, wherein the conductor (2) has at least one groove (21).

6. Busbar (1) according to any one of the preceding claims, wherein the sheathing (3) comprises an inner layer (31) and an outer layer (32), the inner layer (31) being in contact with the conductor (2) and having a higher coefficient of thermal expansion than the outer layer (32).

7. Busbar (1) according to any one of the preceding claims, wherein the sealing element is configured to provide a connection with the conductor (2) and / or the sheathing (3), in particular by comprising at least one adhesive layer (51, 52).

8. Busbar (1) according to one of the preceding claims, comprising a recess (61) between the conductor (2) and the sheathing (3) for receiving the sealing element.

9. Busbar (1) according to one of the preceding claims, wherein the sealing element is designed as a potting compound (6).

10. Busbar (1) according to one of the preceding claims, wherein the sealing element has an internal adhesive layer (51) facing the conductor (2), wherein the internal adhesive layer (51) in particular comprises an adhesive comprising polyamide.

11. Busbar (1) according to one of the preceding claims, wherein the sealing element has an external adhesive layer (52) facing the sheathing (3).

12. Busbar (1 ) according to claim 11, wherein the outer adhesive layer (52) comprises a material that can be activated by heat and / or inductive energy input, preferably a hot melt adhesive.

13. Busbar (1) according to claim 11 or 12, wherein the outer adhesive layer (52) comprises an EVA (ethylene vinyl acetate) material.

14. Busbar (1) according to one of the preceding claims, wherein the splash ring (7) has the same material as the casing (3).

15. Busbar (1) according to any one of the preceding claims, wherein the sealing lip (8) comprises liquid silicone rubber (LSR).

16. Busbar (1) according to any one of the preceding claims, wherein the sealing lip (8) surrounds the injection ring (7) over its entire circumference.

17. Busbar (1 ) according to one of the preceding claims, wherein the sealing lip (8) is arranged on a surface of the splash ring (7) facing the conductor (2).

18. Busbar (1 ) according to one of the preceding claims, wherein the splash ring (7) is arranged on the conductor (2) such that the sealing lip (8) is mechanically pressed against the conductor (2).

19. Busbar (1 ) according to one of the preceding claims, wherein the splash ring (7) is designed with a melting rib (9), wherein the thickness of the at least one melting rib (9) is in particular between 0.05 and 0.3 mm, preferably between 0.1 and 0.25 mm, and particularly preferably between 0.1 and 0.2 mm.

20. Busbar (1 ) according to claim 19, wherein the at least one melting fin (9) is arranged on a surface of the splash ring (9) facing the casing (3).

21. Busbar (1) according to one of the preceding claims, wherein an outer surface of the casing (3) has a structuring (33) and / or a coating.

22. Busbar (1) according to one of the preceding claims, wherein a surface of the conductor (2) has a structuring.

23. Busbar (1) according to one of the preceding claims, wherein a geometry of the conductor (2), in particular an outer radius of the conductor (2), is designed such that a connection between the conductor (2) and the sheathing (3) is media-tight even in extreme thermal stress situations.

24. Manufacturing method for providing a busbar (1), in particular a busbar (1) according to one of claims 1 to 23, comprising the steps: Providing (S100) a conductor (2) made of an electrically conductive material; Media-tight encapsulation (S200), in particular overmolding, of the conductor (2) with a heat-resistant material; and arrangement of a sealing element between the conductor (2) and a sheath (3) produced or to be produced during the encapsulation (S200), wherein the arrangement prior to sheathing (S200) comprises the mounting (S110) of a sealing element designed as a flexible, heat-shrinkable tube (5) having at least one adhesive layer (51, 52) on the conductor (2); or a sealing element designed as a splash ring (7) on the conductor (2), wherein the splash ring (7) has a sealing lip (8).

25. Manufacturing method according to claim 24, wherein the coating (S200) comprises an application, in particular overmolding, in two steps, wherein the first step (S210) comprises the application of an inner layer (31) and the second step (S220) comprises the application of an outer layer (32), and wherein the material of the inner layer (31) has a higher coefficient of thermal expansion than the material of the outer layer (32).

26. Manufacturing method according to claim 24, wherein the flexible, heat-shrinkable tube (5) has an internal adhesive layer (51) contacting the electrical conductor (2), comprising activation of the internal adhesive layer (51), in particular heating of the flexible, heat-shrinkable tube (5).

27. Manufacturing method according to claim 24 or 26, wherein the flexible, heat-shrinkable tube (5) has an outer adhesive layer (52) contacting the sheathing (3), comprising activation of the outer adhesive layer (52), in particular by heat, preferably by heat treatment of the sheathing (S200).

28. Manufacturing method according to claim 24, wherein the arrangement after sheathing (S200) comprises applying (S320) a sealing element designed as a potting compound (6) between the sheathing (3) and the conductor (2).

29. Manufacturing method according to claim 24, wherein the sealing lip (8) is provided by overmolding the injection ring (7), in particular by completely overmolding the injection ring (7).

30. Manufacturing method according to claim 24 or 29, wherein the assembly (S110) of the injection ring (7) comprises a mechanical compression of the sealing lip (8) with the conductor (2).

31. Manufacturing method according to one of claims 24, 29 or 30, wherein the injection ring (7) is joined to the sheathing (3) by means of overmolding, in particular in the media-tight sheathing (S200) of the conductor (2) with the sheathing (3).

32. Manufacturing method according to one of claims 24 or 29 to 31, comprising melting at least one melting fin (9) onto the injection ring (7), in particular during the media-tight encapsulation (S200) of the conductor (2) with the sheathing (3), preferably on a surface of the injection ring (7) facing the sheathing (3).

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