Guide structure of shielded electrical wire

Abstract

Guide structure of a shielded electrical wire (1), wherein the shielded electrical wire (1), comprising an electrical wire (10) and a resin tube (20) covering the electrical wire (10), is guided in a bent state, wherein the resin tube (20) comprises a shielding layer (21), an inner resin (22) and an outer resin (23), wherein the shielding layer (21) is arranged between the inner resin (22) and the outer resin (23), wherein the resin tube (20) is designed such that the tensile strength of the inner resin (22) and the outer resin (23) is greater than the bending stress that is to be generated when the shielded electrical wire (1) is bent with a minimum bending radius in the guide structure, characterized in that the shielding layer (21) has a shielding resistance equal to or less than 103.8 mΩ / m and a shielding density equal to or greater than 50%, wherein the shielding density is a ratio of an area of ​​a surface of the electrical wire (10) covered by the shielding layer (21) to an area of ​​the total surface of the electrical wire (10), wherein the shielding layer (21) is formed in a grid shape with spaces (S) provided at a predetermined distance, and wherein the resin tube (20) is designed such that the inner resin (22) and the outer resin (23) are connected to each other in the spaces (S), and a range of each of the spaces (S) 5 mm 2 or more.

Description

TECHNICAL FIELD

[0001] The present invention relates to a guide structure of a shielded electric wire. BACKGROUND

[0002] In a shielded electric wire of a related art, a rod-shaped conductor is covered with an insulating sheath tube containing a shielding braid (see, for example, JP 2020 - 35677 A). In this shielded electric wire, the insulating sheath tube has an inner layer and an outer layer, and a shielding layer is arranged between the inner layer and the outer layer.

[0003] However, the shielded electric wire of the related art is not intended for use in a portion where the shielded electric wire needs to be bent, and there is a possibility that the desired heat dissipation performance cannot be ensured at the bent portion. Furthermore, there is a possibility that sufficient shielding performance cannot be obtained due to the design of the shielding layer.

[0004] DE 600 16 319 T2 describes an elementary wire for a coaxial cable, a coaxial cable and a coaxial cable bundle, according to the preamble of claim 1.

[0005] JP 2012 - 80 635 A relates to a shielding tube and a wiring harness. To verify the relationship between shielding performance and operating temperature, the resistance value of the metal layer of the shielding tube formed with a 25 μm thick metal layer was adjusted to the resistance in operating environments of 25°C, 80°C, and 120°C, and the value was measured.

[0006] US 2015 / 0 170 790 A1 describes systems and methods for constructing resin-infused cables. Electrical wiring harnesses may include an electrically conductive wire and a resin-infused braided shield surrounding a portion of the electrically conductive wire, with at least a portion of the braided shield being infused with a curable resin. An exemplary coverage of the braided shield may be between approximately 60% and 99.8%.

[0007] US 2018 / 0 065 216 A1 describes a method for forming energy-dissipative tubes. The tube is surrounded by a first resin layer, a metal layer, and a second resin layer. The metal of the metal layer can be formed into foils, perforated foils, tapes, perforated tapes, cables, wires, strands, meshes, braids, and the like. The metal layer can be embedded or partially embedded in one or both resin layers. This can be achieved by pressing the metal layer into the resin layer while the resin cures. SUMMARY

[0008] The present invention provides a guide structure of a shielded electric wire configured to suppress a reduction in heat dissipation performance and ensure shielding performance.

[0009] According to the present invention, as defined in claim 1, there is provided a shielded electric wire guide structure, wherein the shielded electric wire comprising an electric wire and a resin tube covering the electric wire is guided in a bent state, the resin tube having a shielding layer, an inner-side resin, and an outer-side resin, the shielding layer being sandwiched between the inner-side resin and the outer-side resin. The resin tube is configured such that a tensile strength of the inner-side resin and the outer-side resin is greater than a bending stress to be generated when the shielded electric wire is bent with a minimum bending radius in the guide structure.The shielding layer has a shielding resistance equal to or less than 103.8 mΩ / m and a shielding density equal to or greater than 50%, where the shielding density is a ratio of an area of ​​a surface of the electric wire covered by the shielding layer to an area of ​​a total surface of the electric wire. The shielding layer is formed in a lattice shape with gaps provided at a predetermined pitch. The resin tube is configured such that the inner side resin and the outer side resin are bonded to each other in the gaps, and an area of ​​each of the gaps is 5 mm. 2 or more.

[0010] Other aspects and advantages of the invention will become apparent from the following description, drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing an example of a guide structure of a shielded electric wire according to an embodiment of the present invention; Fig. 2A is a detailed configuration diagram of the Fig. 1, and shows a cross-sectional view thereof; Fig. 2B is a detailed configuration diagram of the Fig. 1, and shows a partial configuration thereof; Fig. 3 is a diagram showing a shielding effect for each frequency according to a shielding resistance and a shielding density; Fig. 4 is a partially enlarged view of a Fig. 2B shown shielding layer; and Fig. 5 is a conceptual diagram showing a state of bending a resin pipe. DESCRIPTION OF EMBODIMENTS

[0011] Hereinafter, the present invention will be described according to a preferred embodiment. The present invention is not limited to the embodiment to be described below, and can be modified as appropriate without departing from the gist of the present invention. Furthermore, although some configurations are not shown or described in the embodiment to be described below, it goes without saying that a known or well-known technique is applied to details of an omitted technique as appropriate, within a range where no contradiction occurs with the contents to be described below.

[0012] Fig. 1 is a perspective view showing an example of a shielded electric wire guide structure according to an embodiment of the present invention. As shown in Fig. As shown in Figure 1, a shielded electric wire 1 is routed in a state where it is bent at a plurality of bends B (the number of bends B may be one) according to a vehicle shape, for example, in a vehicle. With the following configuration, the shielded electric wire 1 ensures both shielding performance and heat dissipation performance at the bend B.

[0013] In Fig. 1, the shielded electric wire 1 is routed in an exposed state, but the configuration is not particularly limited thereto, and the shielded electric wire 1 may be routed in a state where a protective tube such as a corrugated tube / hose is provided. Furthermore, the shielded electric wire 1 may be routed together with other electric wires.

[0014] Fig. 2A is a detailed configuration diagram of the Fig. 1, and shows a cross-sectional view thereof. Fig. 2B is a detailed configuration diagram of the Fig. 1, and shows a partial configuration thereof. As shown in Fig. As shown in Fig. 2A, the shielded electric wire 1 includes an electric wire 10 and a resin tube 20.

[0015] The electric wire 10 is a rod-shaped conductor, i.e., a bare electric wire. The electric wire 10 is made of, for example, copper, aluminum, or an alloy thereof. Although the electric wire 10 in the Fig. 2A is a bare electric wire, the electric wire 10 is not particularly limited thereto, and may be a coated electric wire having an insulating sheath.

[0016] As in Fig. 2A and Fig. As shown in Figure 2B, the resin tube 20 is a tubular member made of an insulating resin and includes a shielding layer 21 having a shielding function. Specifically, the resin tube 20 includes an inner-side resin 22 serving as a tube inner surface, an outer-side resin 23 serving as a tube outer surface, and the shielding layer 21 disposed between the inner-side resin 22 and the outer-side resin 23.

[0017] The shielding layer 21 may be a braid made of a metal wire or may be a metal foil. Examples of the metal of the shielding layer 21 include copper, aluminum, iron, stainless steel, and alloys thereof. To improve durability, a clad fiber conductor in which a high-strength fiber is clad with a metal may be used as a material of the shielding layer 21. Here, the high-strength fiber is a fiber material chemically synthesized from a raw material such as petroleum, and has a tensile strength at break equal to or greater than 1 GPa and an elongation percentage at break of 1% or more and 10% or less. Examples of such a fiber include an aramid fiber, a polyacrylate fiber, and a PBO fiber. The high-strength fiber is plated with copper, nickel, tin, gold, silver, an alloy thereof, or the like.

[0018] Here, in the present embodiment, the shielding layer 21 has a shielding resistance of 103.8 mΩ / m or less, and a shielding density thereof, which is a ratio of an area of ​​a surface of the electric wire 10 covered by the shielding layer 21 to an area of ​​a whole of the surface of the electric wire 10, is 50% or more.

[0019] Fig. Figure 3 is a diagram showing a shielding effect for each frequency according to the shield resistance (SR in Fig. 3) and a shield density (SD in Fig. 3) shows. The Fig. The shielding effect shown in Figure 3 is a result obtained by measuring using an absorber clamp method. Generally, when the shielding effect is 30 dB or more, it is said that there is a noise suppression effect to such an extent that a mobile phone is out of range. Even with the shielded electric wire 1 according to the present embodiment, the shielding effect of 30 dB is ensured.

[0020] Here, as in Fig. As shown in Figure 3, in a low-frequency range (a range of 1 MHz or less), the shielding effect tends to improve as the shielding resistance decreases. Therefore, to ensure a shielding effect of 30 dB in the entire range of 10 kHz or more and 1 MHz or less, the shielding resistance must be 103.8 mΩ / m or less.

[0021] On the other hand, in a high-frequency range (a range exceeding 1 MHz), the shielding effect tends to improve as the shielding density decreases. Therefore, to ensure a shielding effect of 30 dB in the entire range of 1 MHz or more and 1 GHz or less, the shielding density must be 50% or more.

[0022] As described above, in the present embodiment, when the shielding resistance of the shielding layer 21 is set to be equal to or less than 103.8 mΩ / m and the shielding density is set to be equal to or greater than 50%, the shielding effect equal to or greater than 30 dB can be ensured in the entire range of 10 kHz or more and 1 GHz or less.

[0023] Fig. 4 is a partially enlarged view of the Fig. 2B. Furthermore, as shown in the enlarged view of Fig. 4, the shielding layer 21 is formed in a lattice shape with spaces S at a predetermined distance therebetween. Although in the Fig. 4, the shielding layer 21 is formed of a metal wire or a plated fiber in a lattice shape, the shielding layer 21 is not limited to this, and may be formed of a metal foil in a lattice shape.

[0024] Since such a mesh-shaped shielding layer 21 is used, the inner resin 22 and the outer resin 23 are bonded together in the gaps S of the mesh in the resin tube 20. As a result, the occurrence of a positional deviation between the shielding layer 21 and the resins can be made less likely. An area of ​​the gap S is 5 mm according to the invention. 2or more. This is because when the area of ​​the gap S is less than 5 mm2, the bonding between the inner side resin 22 and the outer side resin 23 becomes insufficient, and the effect of preventing positional deviation is reduced.

[0025] Furthermore, in the present embodiment, a tensile strength of the resin constituting the resin tube 20 is appropriately determined. That is, in the resin tube 20 according to the present embodiment, a tensile strength of the resin constituting the resin tube 20 is set to exceed a bending stress that can be achieved at a minimum bending radius with respect to the minimum bending radius among the plurality of Fig. 1 shown bends B (the bend B can be one).

[0026] Fig. 5 is a conceptual diagram showing a state of bending the resin pipe 20. As in Fig.5, the resin tube 20 is bent at the bend B, and a crack is generated from an outer side of the bend B, or a defect is generated at an inner side due to cross-sectional reduction. Such a portion becomes an air layer A. The air layer A has a lower thermal conductivity than that of each member (resin or the shielding layer 21) constituting the resin tube 20. For this reason, if the air layer A is formed at the bend B, a reduction in heat dissipation performance may be caused. In the present embodiment, however, since the tensile strength of the resin tube 20, ieBy increasing the tensile strength of the inner resin 22 and the outer resin 23 to exceed the bending stress generated when the shielded electric wire 1 is bent with the minimum bending radius in the guide structure, it is possible to reduce the possibility of the air layer A being formed due to the generation of a crack or the like. Therefore, a reduction in heat dissipation performance is suppressed.

[0027] Specifically, a bending stress 6 can be expressed by δ = E(y / r). Here, E is a longitudinal section coefficient (elastic modulus), y is a distance from a neutral axis, and r is a bending radius. E and y can be obtained based on the resin and a size used for the resin tube 20. Therefore, if the minimum bending radius is known, the bending stress is also known. In the shielded electric wire 1 according to the present embodiment, the material and the like of the resin tube 20 are determined in advance according to the minimum bending radius at the time of laying.

[0028] Next, a manufacturing method and operation of a guide structure of the shielded electric wire 1 according to the present embodiment will be described. First, the tensile strength of the shielded electric wire 1 is to be set according to a shape of the shielded electric wire 1 during routing (specifically, according to a minimum bending radius of bends of the shielded electric wire 1). For example, a size (thickness) of the resin tube 20 is determined according to a size of the electric wire. Consequently, a value of y in the bending stress δ = E(y / r) is determined. Next, a value of r is determined based on the minimum bending radius. The elastic modulus E is determined based on the material used for the resin tube 20, and the bending stress δ is obtained.For the resin pipe 20, a material having a tensile strength exceeding the bending stress δ is selected, and the resin pipe 20 is manufactured with the material.

[0029] In the resin pipe 20 manufactured in this way, cracks or the like are not generated in the bend B, and the air layer A is less likely to be formed. Therefore, heat dissipation performance is ensured.

[0030] Furthermore, in the present embodiment, the shielding layer 21 has a shielding resistance of 103.8 mΩ / m or less and a shielding density of 50% or more, and thus the shielding effect of 30 dB is ensured in the entire range of 10 kHz or more and 1 GHz or less.

[0031] In particular, since the shielding layer 21 is formed in a lattice shape, the inner side resin 22 and the outer side resin 23 are bonded together in the gap S of the lattice, and the formation of the air layer A due to deviation between the resin and the shielding layer 21 is suppressed. Thus, the heat dissipation performance can be more easily ensured.

[0032] In this way, according to the guide structure of the shielded electric wire 1 according to the present embodiment, since the tensile strength of the resin of the resin tube 20 exceeds the bending stress at the time of bending generated when the shielded electric wire 1 is bent with the minimum bending radius at the bend B in the guide structure, it is possible to prevent a situation in which a crack or the like is generated due to the bending of the resin tube 20 at the bend B and the formation of the air layer A, which causes a reduction in heat dissipation performance. In addition, since the shielding layer 21 has a shielding resistance of 103.8 mΩ / m or less and a shielding density of 50% or more, the shielding performance of 30 dB can be ensured in both a low-frequency range and a high-frequency range.Therefore, it is possible to suppress a reduction in heat dissipation performance and ensure the shielding performance.

[0033] The shielding layer 21 is formed in a lattice shape with gaps S at a predetermined pitch, and in the resin tube 20, the inner side resin 22 and the outer side resin 23 are bonded to each other at the gaps S of the lattice of the shielding layer 21. Therefore, with the bonding at the gaps S of the lattice at the bend B, it is possible to reduce a possibility that a positional relationship between the shielding layer 21 and the resin is changed and air enters a deviated portion, causing a reduction in heat dissipation performance.

[0034] While the present invention has been described with reference to certain exemplary embodiments thereof, the scope of the present invention is not limited to the exemplary embodiments described above, and those skilled in the art will understand that various changes and modifications may be made therein without departing from the scope of the present invention as defined by the appended claim.

[0035] For example, the materials and the like are not limited to those described above and can be changed as appropriate. Furthermore, the shielded electric wire 1 according to the embodiment may not be formed in a lattice shape. For example, metal wires, metal foils, or the like of the shielded electric wire 1 may be arranged in a spiral shape or the like, or may be arranged along an axial direction of the shielded electric wire 1.

Claims

[1] A guide structure of a shielded electric wire (1), wherein the shielded electric wire (1) comprising an electric wire (10) and a resin tube (20) covering the electric wire (10) is guided in a bent state, wherein the resin tube (20) has a shielding layer (21), an inner side resin (22) and an outer side resin (23), wherein the shielding layer (21) is arranged between the inner side resin (22) and the outer side resin (23), wherein the resin tube (20) is designed such that a tensile strength of the inner side resin (22) and the outer side resin (23) is greater than a bending stress to be generated when the shielded electric wire (1) is bent with a minimum bending radius in the guide structure, characterized bythat the shielding layer (21) has a shielding resistance equal to or less than 103.8 mΩ / m and a shielding density equal to or greater than 50%, wherein the shielding density is a ratio of an area of ​​a surface of the electric wire (10) covered by the shielding layer (21) to an area of ​​a total of the surface of the electric wire (10), wherein the shielding layer (21) is formed in a lattice shape with spaces (S) provided at a predetermined interval, and wherein the resin tube (20) is designed such that the inner side resin (22) and the outer side resin (23) are connected to each other in the spaces (S), and an area of ​​each of the spaces (S) 5 mm 2 or more.

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