Electrical conductor with multiple sheathing layers and method for manufacturing such a conductor

Abstract

Electrical conductor with an outer sheath, wherein the outer sheath has several sheath layers made of a polymer, wherein at least two sheath layers have interlocking structures on their mutually facing side surfaces, wherein the interlocking structures of one sheath layer engage with the interlocking structures of the other sheath layer, wherein at least one sheath layer has interlocking structures on two opposite side surfaces, wherein the interlocking structures of each side surface engage with interlocking structures of another sheath layer facing the respective side surface and the interlocking structures engage behind each other, wherein the sheath layers consist of different polymers.

Description

[0001] The invention relates to an electrical conductor with an outer sheath, wherein the outer sheath comprises several sheath layers, and to a method for manufacturing such a conductor.

[0002] Electrical cables are used in many technical fields. For example, they are also components of motor vehicles, particularly in hybrid-electric and fully electric vehicles. Generally, every electrical cable requires an outer sheath to protect against mechanical and electrical faults. The structure of this outer sheath depends on the application of the electrical cable, and may be designed, for example, to ensure sealing or to prevent plastic deformation. To achieve the necessary properties, it is known from the prior art that the outer sheath can be constructed from multiple layers.

[0003] For example, the publication EP 2 426 673 B1 shows an electrical cable in which an additional intermediate sheath is present between the inner part of the cable, which is encased by an inner sheath, and an outer sheath, with the outer sheath resting on the intermediate sheath. In this arrangement, the outer sheath serves the purpose of making the cable suitable for drinking water and resistant to microbial growth.

[0004] German patent application DE 34 44 500 C2 discloses a cable whose core, consisting of one or more conductors, is surrounded by a sheath made of insulating materials. The outer layer of this sheath is made entirely or partially of a thermoplastic, radiation-crosslinked polyurethane to protect the core against external mechanical stress and to maintain the protective function of the outer sheath for at least a certain period of time when exposed to heat.

[0005] Publication US 2015 / 0279515A1 discloses a cable with a two-layer outer sheath, in which the outermost layer is made of a biocompatible material, the underlying sheath layer acting as a buffer layer and being made of an elastic material to ensure stability of the outer sheath even under mechanical stress and biocompatibility.

[0006] In publication EP 2 591 478 A1, a self-supporting cable is disclosed which has a sheath consisting of two layers, wherein these layers are designed in such a way that they can move relative to each other in a longitudinal direction in order to simplify bending of the cable.

[0007] US 2013 / 0048338A1 describes a coated cable comprising a core surrounded by an inner, grooved insulating layer. The grooved insulating layer is encased by at least one further layer, which has structures that engage with the grooves of the inner layer. The grooves of the inner layer increase its surface area facing the outer layer, thereby improving adhesion between the layers. The outer layer may have structures with a rectangular cross-section that engage between the trapezoidal structures that define the grooves of the inner layer. However, the rectangular structures do not engage behind the trapezoidal structures.

[0008] US 2016 / 0238166A1 describes a corrugated sleeve for sheathing a cable. The sleeve comprises two adjacent layers of a polymer, with the inner damping layer having a corrugated structure into which the outer layer engages. The outer layer follows the course of the U-shaped corrugations of the inner layer.

[0009] US Patent 6,906,264 B1 discloses a color-coded, metal-reinforced cable. The multiple conductors inside the cable are spirally enclosed by a metal strip with an S-shaped cross-section. The metal strip is wound in such a way that the S-shaped cross-section engages with the preceding and subsequent windings.

[0010] US 4,731,502 A describes an electrical conductor with an outer sheath consisting of two sheath layers. Interlocking structures between the sheath layers are not provided.

[0011] EP 2 672 491 A1 describes a cable with a mechanically resistant sheath that exhibits good resistance due to the manufacturing process. It is characterized by the fact that the sheath, which is single-layered or multi-layered, preferably two-layered, possesses higher resistance resulting from the extrusion process. In a two-layer construction, corresponding interlocking structures are incorporated.

[0012] A disadvantage of outer walls for electrical cables constructed in this way is that sufficient adhesion between the sheath layers is not guaranteed for every material combination, which can lead to deformation of the outer sheath when mechanical forces are applied, thereby impairing its protective function for the inside of the cable.

[0013] The invention is therefore based on the objective of providing an electrical conductor with an outer sheath consisting of several layers, in which the layers form a sufficiently stable connection regardless of the choice of material.

[0014] To solve this problem, the invention provides that at least two cladding layers have engagement structures on their mutually facing side surfaces, wherein the engagement structures of one cladding layer engage with the engagement structures of the other cladding layer.

[0015] The advantage of the solution according to the invention lies in the fact that the interlocking of the engagement structures results in an improved positive-locking connection between the two sheath layers. Thus, for example, in the case of two sheath layers made of different materials that adhere only inadequately to each other, a stable connection between the two sheath layers is achieved, preventing detachment, warping, or stretching, particularly of the outer sheath layer, as a result of mechanical stress. In particular, the engagement structures of an inner, first sheath layer and the engagement structures of a second sheath layer surrounding this first sheath layer can be shaped complementarily to each other in order to obtain the largest possible contact area between the engagement structures. The interior of the electrical conductor to be sheathed can be of any design.For example, it is possible to sheath single- or multi-core cables, whereby the core or cores of the cable may have a single- or multi-layer inner sheath and / or a sheath consisting of one or more insulating layers.

[0016] According to the invention, the electrical conductor is designed such that at least one sheath layer has interlocking structures on two opposite side surfaces, wherein the interlocking structures of each side surface engage with interlocking structures of another sheath layer facing the respective side surface. This makes it possible to form a multilayer stack of sheath layers connected by interlocking structures, in which the sheath layers are connected to each other by their interlocking interlocking structures. It is also possible that, in an outer sheath consisting of several layers, some of the layers lie smoothly against each other and have no interlocking structures at the interface with another layer, whereas the other part is connected to each other via interlocking structures at the interfaces of the sheath layers.Different materials are used for the respective layers of the outer shell, so that different material combinations and / or material sequences can be realized for the entire outer shell.

[0017] The engagement structures interlock with each other. This interlocking further increases the stability of the positive-locking connection formed by the engagement of the structures of two sheath layers. For example, the interlocking can be achieved by the engagement structures of a first sheath layer having an undercut geometry in their cross-section, with the engagement structures of a second sheath layer engaging into the undercut space when they engage with the structures of the first sheath layer. This prevents the sheath layer from separating under a force acting, for example, perpendicular to the contact surface between the sheath layers.

[0018] The intervention structures can be designed with trapezoidal, I-shaped, L-shaped, T-shaped, convexly curved, and / or concavely curved cross-sections. Depending on their arrangement and orientation, these intervention structures exhibit an undercut geometry, enabling engagement or access from behind. The intervention structures of a shell layer can all have the same cross-sectional shape, or intervention structures with different cross-sectional shapes can be arranged circumferentially in any number and sequence. For example, alternating I-shaped and T-shaped cross-sections can be implemented for the intervention structures.Depending on the cross-sectional geometry of the engagement structures, circumferentially asymmetrical arrangements can be achieved, for example, when using engagement structures with an L-shaped cross-section oriented in the same direction, or circumferentially symmetrical arrangements, for example, when using engagement structures with a T-shaped cross-section. A symmetrical arrangement offers the advantage that, in the event of torsion of the second shell layer relative to the first shell layer along both directions of rotation in the circumferential direction, the connection created by the interlocking engagement structures maintains the same stability. The engagement structures of a second shell layer, which engage with or behind the engagement structures of a first shell layer, preferably have cross-sectional geometries arranged such that they are complementary to the engagement structures of the first shell layer.This ensures a precise intervention or countermeasure of the intervention structures.

[0019] The electrical conductor according to the invention is further designed such that the sheath layers consist of a polymer. The use of different polymer materials for the sheath layers offers the advantage that the properties of the outer sheath, with regard to its protective effect, can be flexibly adapted to the requirements of the electrical conductor. In particular, adjustments can be made with regard to the electrical insulation capacity of the outer sheath, as well as its mechanical stability and its resistance to plastic deformation.

[0020] In a preferred embodiment of the invention, one of two sheath layers with interlocking or overlapping engagement structures is made of polyurethane and the other of silicone. For example, an inner sheath layer can be made of silicone, and an outer layer of the outer sheath enclosing this inner layer can be made of polyurethane. This provides the polyurethane sheath with protection for the electrical conductor, but, due to the inner silicone layer, reduces the degree of plastic deformation compared to an outer sheath of the same thickness made entirely of polyurethane. The engagement of the engagement structures provided on both layers ensures the mechanical stability of this outer sheath arrangement.

[0021] Furthermore, according to the invention, the electrical conductor may have a connection means, in particular for a plug connection, at at least one of its ends. With the aid of this connection means, it is possible, for example, for the electrical conductor to be connected and used in an electrical arrangement according to its intended purpose.

[0022] The electrical cable may also be designed to be a high-voltage cable. For example, such a high-voltage cable can connect various high-voltage components in a hybrid-electric or fully electric vehicle.

[0023] In addition to the electrical conductor, the invention relates to a method for producing an electrical conductor according to the invention, comprising the steps: - Provision of the interior of the electrical conductor to be sheathed, - Application of a first mantle layer enclosing the interior, wherein the first mantle layer has interlocking structures on its outwardly facing side surface, - Applying a second mantle layer, wherein the second mantle layer has engagement structures on its inward-facing side surface that engage with the engagement structures of the first mantle layer, wherein, when applying the second mantle layer, the outward-facing side surface of the second mantle layer also has engagement structures, after which a third mantle layer is applied, wherein the third mantle layer has engagement structures on its inward-facing side surface that engage with the engagement structures on the outward-facing side surface of the second mantle layer, wherein the engagement structures interlock behind each other when engaging. - where the three jacket layers consist of different polymers.

[0024] Using this method, electrical conductors with the features according to the invention can be manufactured, and it is particularly possible to produce the engagement structures of the first and second sheath layers with any cross-sectional geometry, so that they can interlock or overlap. The application of the second sheath layer can be carried out in such a way that the layer material of the second sheath layer conforms to the engagement structures of the first sheath layer and thereby forms engagement structures that are complementary to the engagement structures of the first sheath layer. In particular, if the engagement structures of the first sheath layer have an undercut cross-sectional geometry, this method results in the engagement structures of the second sheath layer overlapping the engagement structures of the first sheath layer and the second sheath layer being positively connected to the first sheath layer.

[0025] When the second mantle layer is applied, its outward-facing side surface also features interlocking structures. A third mantle layer is then applied, this third layer having interlocking structures on its inward-facing surface that engage with the interlocking structures on the outward-facing side surface of the second mantle layer. It is also possible that the connection between the second and third mantle layers is achieved through interlocking interlocking structures.

[0026] Furthermore, the inventive method can be provided for the application of the sheath layers by extrusion. During the extrusion of the polymer material of a sheath layer, interlocking structures with any desired arrangement of cross-sectional shapes can be produced directly in the manufacturing process.

[0027] Further advantages and details of the invention will become apparent from the exemplary embodiments described below and from the drawings. These show: Fig. 1 a perspective, cutaway view of an embodiment of an electrical conductor not according to the invention, Fig. 2 a cutaway view of an embodiment of an electrical conductor not according to the invention with trapezoidal engagement structures, Fig. 3 a cutaway view of an embodiment of an electrical conductor not according to the invention with concave and convex curved engagement structures, Fig. 4 a cutaway view of an embodiment of an electrical conductor not according to the invention with circumferentially asymmetrical arrangement of engagement structures with L-shaped cross-section, as well as Fig. 5 a cutaway view of an embodiment of an electrical conductor according to the invention with three sheath layers connected via interlocking engagement structures.

[0028] For the sake of clarity, the following were included in the illustrations: Fig. 1 to Fig. 5. Not all depicted intervention structures are provided with their own reference symbol.

[0029] The in Fig. The electrical conductor 1 shown in Figure 1 has a conductor interior 2 designed as a single-core cable for conducting current in a high-voltage line, which is sheathed by a first sheath layer 3 and a second sheath layer 4. The first sheath layer 3, which encloses the conductor interior 2, has I-shaped interlocking structures 5 on its outward-facing side surface. The second sheath layer 4, which encloses the first sheath layer 3 and forms the outer boundary of the electrical conductor, has I-shaped interlocking structures 6 on its inward-facing side surface. Due to the interlocking structures 5, 6, a stable, form-fitting connection is created between the first sheath layer 3 and the second sheath layer 4. The sheath layers 3, 4 are made of different polymer materials. The first sheath layer 3 is made of silicone, for example, and the second sheath layer 4 of polyurethane.This material combination can also be used in the other embodiments.

[0030] By extruding the material of the first sheath layer 3 onto the conductor interior 2, the interlocking structures 5 of the first sheath layer 3 can be generated directly during the application of the first sheath layer 3. The interlocking structures 6 of the second sheath layer 4, which are shaped complementarily to the interlocking structures 5 of the first sheath layer 3, are formed accordingly by extruding the material of the second sheath layer 4 onto the first sheath layer 3. This results in the interlocking structures 5 and 6 directly interlocking, and the first sheath layer 3 and the second sheath layer 4 lying against each other without any gaps. After the sheath layers have been applied, the electrical conductor can be fitted with connectors such as plugs at its ends.

[0031] The following examples of embodiments can also be produced using such a method.

[0032] In Fig. Figure 2 shows a further embodiment of an electrical conductor 1 not according to the invention. Here, the first sheath layer 3, which encloses the interior of the conductor 2, has trapezoidal engagement structures 7 on its outwardly facing surface. These trapezoidal engagement structures 7 have an undercut geometry in their cross-section, so that the similarly trapezoidal engagement structures 8 of the second sheath layer 4, which also encloses the first sheath layer 3, engage behind it. This engagement creates a positive connection between the sheath layers, thereby achieving improved mechanical stability of the sheath layer arrangement against a force acting in the radial direction in this example. The trapezoidal engagement structures 7 of the first sheath layer 3 and the trapezoidal engagement structures 8 of the second sheath layer 4 are complementary in shape.

[0033] At the in Fig. In the further embodiment of an electrical conductor not according to the invention shown in Figure 3, the first sheath layer 3 has concave undercut engagement structures 9 that engage with and behind the convex undercut engagement structures 10 of the second sheath layer 4. The positive-locking connection between the engagement structures 9 of the first sheath layer 3 and the engagement structures 10 of the second sheath layer 4 prevents the second sheath layer 4 from separating from the first sheath layer 3.

[0034] At the in Fig. In the embodiment of an electrical conductor not according to the invention, shown in Figure 4, the first sheath layer 3 has L-shaped engagement structures 11 which engage in the complementary and therefore also L-shaped engagement structures 12 of the second sheath layer 4 and interlock them in a form-fitting manner. Because the L-shaped engagement structures are all oriented in the same way, an arrangement is created that is asymmetrical with respect to a circumferential torsional force acting on the second sheath layer 4. This differs from the one shown in Figure 4. Fig. Examples 1-3 are shown, where the arrangements are symmetrical with respect to such a force.

[0035] In Fig.Figure 5 shows an electrical conductor 1, which has a first sheath 3 enclosing the conductor's interior 2, an adjacent second sheath 4, and a third sheath 13 adjacent to the second sheath 4, which forms the outer boundary of the electrical conductor 1. The first sheath 3 has T-shaped engagement structures 14 on its outward-facing side surface, which interlock with the T-shaped engagement structures 15 on the inward-facing side surface of the second sheath 4. In this example, the second sheath 4 also has trapezoidal engagement structures 16 on its outward-facing side surface, which interlock with the trapezoidal engagement structures 17 on the inward-facing side of the third sheath 13.

[0036] In this embodiment, the first jacket layer 3 and the third jacket layer 13 can be made of polyurethane and the second jacket layer 4 of silicone, or all three jacket layers can be made of different polymeric materials, so that, for example, the third jacket layer 13 is made of polyurethane, the second jacket layer 4 of silicone and the first jacket layer 3 of another polymeric material.

[0037] Furthermore, it is possible to provide the third sheath layer 13 with additional interlocking structures on its outer surface and to apply further sheath layers, thus enabling an outer sheath consisting of any number of sheath layers connected to each other by interlocking interlocking structures. The individual sheath layers can have identically shaped interlocking structures, or any combination of cross-sectional shapes of the interlocking structures can be used for a single sheath layer and / or for different sheath layers. In the case of stably adhering material pairings, the corresponding sheath layers 4 and 13 can also lie smoothly against each other at the adjacent sheath surfaces, i.e., without interlocking structures.

Claims

[1] Electrical conductor with an outer sheath, wherein the outer sheath has several sheath layers made of a polymer, wherein at least two sheath layers have interlocking structures on their mutually facing side surfaces, wherein the interlocking structures of one sheath layer engage with the interlocking structures of the other sheath layer, wherein at least one sheath layer has interlocking structures on two opposite side surfaces, wherein the interlocking structures of each side surface engage with interlocking structures of another sheath layer facing the respective side surface and the interlocking structures engage behind each other, wherein the sheath layers consist of different polymers. [2] Electrical conductor according to claim 1, characterized by that the intervention structures are trapezoidal, I-shaped, L-shaped, T-shaped, convexly curved and / or concavely curved in cross-section. [3] Electrical conductor according to any of the preceding claims, characterized by , that of two sheath layers with interlocking or overlapping intervention structures, one sheath layer consists of polyurethane and the other of silicone. [4] Electrical conductor according to any of the preceding claims, characterized by that the electrical conductor has a connection means, in particular for a plug connection, at at least one of its ends. [5] Electrical conductor according to any of the preceding claims, characterized by that the electrical line is a high-voltage line. [6] A method for producing an electrical conductor according to any of the preceding claims comprising the steps • Provision of the interior of the electrical conductor to be sheathed, • Application of a first encasing layer of a polymer, wherein the first encasing layer has interlocking structures on its outward-facing side surface, • Applying a second coating layer made of a polymer, wherein the second coating layer has engagement structures on its inward-facing side surface that engage with the engagement structures of the first coating layer, wherein the engagement structures interlock behind each other when engaging, wherein, when applying the second coating layer, the outward-facing side surface of the second coating layer also has engagement structures, after which a third coating layer is applied, wherein the third coating layer has engagement structures on its inward-facing side surface that engage with the engagement structures on the outward-facing side surface of the second coating layer, wherein the engagement structures interlock behind each other when engaging. • where the three jacket layers consist of different polymers. [7] Method according to claim 6, characterized by that the application of the jacket layers is done by extrusion.

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