Cable

Abstract

The present disclosure belongs to the technical field of communication. Provided is a cable. The cable comprises a plurality of cores, a plurality of first insulation layers and a second insulation layer, wherein each core is circumferentially covered by the corresponding first insulation layer, and the second insulation layer covers the plurality of first insulation layers; and the second insulation layer has a plurality of hole structures that are not in communication with the outer surface of the second insulation layer, the outer surface of the second insulation layer being the surface that radially faces away from the first insulation layer. In the present disclosure, since the hole structures in the second insulation layer are not in communication with the outer surface of the second insulation layer, the hole structures are closed hole structures and are radially isolated from the external environment, so as to effectively block moisture to make the cable less susceptible to moisture, thereby prolonging the service life of the cable.

Description

Cable

[0001] The present application claims priority to the Chinese patent application No. 202411339934.8, filed on September 24, 2024, and entitled "Cable", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of communication, in particular to a cable. BACKGROUND

[0003] The cable, such as a double-core cable, comprises two conductors, an inner insulation layer covering each conductor, an outer insulation layer covering the inner insulation layer, and a shielding layer and a mica layer covering the outer insulation layer.

[0004] When a signal is transmitted in the cable, there is resistance loss from the conductors and dielectric loss from the insulation layer. For example, the dielectric loss of the insulation layer accounts for 30% of the total loss. Currently, in order to reduce the dielectric loss, the material of the outer insulation layer is generally selected to be expanded polytetrafluoroethylene (EPTFE) with a microporous structure. The EPTFE in the form of a strip is wound around the inner insulation layer by wrapping.

[0005] However, the microporous structure on the outer insulation layer can cause poor water resistance of the cable, making the cable prone to moisture, and reducing the service life of the cable. SUMMARY

[0006] The present disclosure provides a cable, wherein the hole structure of the second insulation layer of the cable and the outer surface of the second insulation layer are not connected, which belongs to a closed hole structure, can effectively isolate the cable from the external environment, so that the cable is not prone to moisture, thereby prolonging the service life of the cable.

[0007] According to the present disclosure, a cable is provided, which comprises a plurality of cores, a first insulation layer and a second insulation layer.

[0008] The circumference of each core is covered with the first insulation layer, and the second insulation layer covers the plurality of first insulation layers.

[0009] The second insulation layer has a plurality of hole structures, and the hole structures are not connected to the outer surface of the second insulation layer, wherein the outer surface of the second insulation layer is a surface that radially faces away from the first insulation layer.

[0010] The first insulation layer is also referred to as an inner insulation layer, and the second insulation layer is also referred to as an outer insulation layer.

[0011] In the scheme shown in the present disclosure, a plurality of hole structures are arranged in the second insulation layer of the cable, the hole structures are not communicated with the outer surface of the second insulation layer and belong to closed hole structures in the radial direction, which can effectively block water vapor, so that the cable is not prone to moisture and the service life of the cable is prolonged.

[0012] In a possible implementation, the hole structure is in the shape of a strip, and the strip direction of the hole structure is parallel to the length direction of the cable.

[0013] In the scheme shown in the present disclosure, the hole structure of the second insulation layer can be a hole structure extending through the length of the cable, or one end of the hole structure is located at the end of the cable and the other end is located in the second insulation layer.

[0014] In the scheme shown in the present disclosure, the hole structure in the second insulation layer is in the shape of a strip, and the two open ends of the hole structure are distributed along the length direction of the cable, so as to be not communicated with the outer surface of the second insulation layer in the radial direction.

[0015] In a possible implementation, the hole structure is a coupling core hole formed by a coupling core process.

[0016] In the scheme shown in the present disclosure, the hole structure is formed by a coupling core process, so that by controlling the number of coupling core structures on the mold, the number of hole structures can be adjusted. Once the number of hole structures is adjustable, the porosity of the second insulation layer can be adjusted, thereby facilitating the balance between the porosity and the mechanical properties of the second insulation layer, so that the cable meets both lower dielectric loss and good mechanical properties.

[0017] In this way, the cable has both high porosity and good mechanical properties. The high porosity of the cable is conducive to reducing the dielectric loss of the cable, and the good mechanical properties of the cable make the cable less likely to deform in a bending scenario, thereby reducing the occurrence of impedance discontinuity and enhancing the signal transmission quality of the cable.

[0018] In a possible implementation, the shape of the cross section of the hole structure is polygonal, circular, elliptical or sectorial.

[0019] In the scheme shown in the present disclosure, the hole structure is formed by a coupling core process, so that by controlling the shape and size of the coupling core structure on the mold, the shape and size of the hole structure can be controlled, which can also regulate the porosity of the second insulation layer to some extent, thereby facilitating the balance between the porosity and the mechanical properties of the second insulation layer, so that the cable meets both lower dielectric loss and good mechanical properties.

[0020] In a possible implementation, the hole structure is formed in the second insulation layer by a foaming process.

[0021] In the scheme shown in the present disclosure, the hole structure in the second insulating layer can also be formed by a foaming process. For example, the raw material used to form the second insulating layer contains a foaming agent, and then the second insulating layer is formed by an extrusion process, and under the action of the foaming agent, the second insulating layer is distributed with more hole structures. Among them, the foaming agent can be a foaming agent used for physical foaming, or a foaming agent used for chemical foaming.

[0022] In a possible implementation, the second insulating layer is formed by an extrusion process.

[0023] In a possible implementation, the material of the second insulating layer is a perfluoropolymer or a polyolefin polymer.

[0024] In the scheme shown in the present disclosure, the perfluoropolymer or the polyolefin polymer has a relatively low dielectric constant and dielectric loss, so that the second insulating layer adopts this material, which can further reduce the insulation loss of the cable.

[0025] In a possible implementation, the material of the second insulating layer is at least one of polyfluoroethylene propylene FEP, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer PFA, polyethylene PE, polypropylene PP, cyclic olefin copolymer COC, and poly-4-methyl-1-pentene TPX.

[0026] In a possible implementation, the cable further includes a shielding layer, and the shielding layer is wrapped outside the second insulating layer in the circumferential direction.

[0027] In the scheme shown in the present disclosure, the shielding layer can be a metal mesh structure, wrapped outside the second insulating layer, for example, wrapped outside all the second insulating layers, to avoid the case that electromagnetic radiation occurs between the cable and other cables.

[0028] In a possible implementation, the cable further includes a protective layer, and the protective layer is wrapped outside the shielding layer in the circumferential direction.

[0029] In the scheme shown in the present disclosure, the protective layer can also be referred to as a Mylar layer, wrapped outside the shielding layer, to protect the shielding layer from corrosion and oxidation. BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a schematic view of a transverse cross-section of a cable according to an example embodiment of the present disclosure;

[0031] FIG. 2 is a schematic view of a transverse cross-section of a cable according to an example embodiment of the present disclosure;

[0032] FIG. 3 is a schematic view of an axial cross-section of a cable according to an example embodiment of the present disclosure;

[0033] Figure 4 is a schematic view of the micro-pores in the second insulating layer according to one example embodiment of the present disclosure;

[0034] Figure 5 is a schematic view of a cross-section of a dual-core cable including a shielding layer and a protective layer according to one example embodiment of the present disclosure.

[0035] Reference numeral explanation

[0036] 1, electrical core; 2, first insulating layer; 3, second insulating layer; 31, pore structure; 4, shielding layer; 5, protective layer. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the embodiments of the present disclosure will be described in further detail below with reference to the drawings.

[0038] The present embodiment relates to a cable, in particular a multi-core cable, including a plurality of electrical cores. The cable can be applied to an active cable, which can be an AEC (active electrical cable) active cable or an ACC (active copper cable) active cable. Regardless of the type of active cable, the active cable is structurally composed of a cable and electrical modules connected to both ends of the cable. In the AEC active cable, the chips in the electrical modules are retimer chips, and in the ACC active cable, the chips in the electrical modules are redriver chips.

[0039] The cable can also be applied to a passive DAC (direct attach cable). The passive DAC is also structurally composed of a cable and electrical modules connected to both ends of the cable, except that the electrical modules do not include active chips. Because the electrical modules of the passive DAC do not include active chips, the passive DAC is generally applied to short-distance interconnection scenarios.

[0040] The cable can also be used to implement in-frame device interconnection. The direct connection of the cable to the device can be that the cable is connected to the device through a cable connector. For example, a single cable is connected to a cable connector, and the cable connector is connected (e.g., plugged or welded, etc.) to the device. For another example, a plurality of cables are bundled together and connected to a cable connector, and the cable connector is connected (e.g., plugged or welded, etc.) to the device.

[0041] In the present embodiment, the specific application scenarios of the cable are not limited, but regardless of the application scenario, the cable described in the present embodiment refers to a raw cable that does not include a connector and does not include an electrical module.

[0042] A double-core cable including two electric cores is widely applied in the communication field due to the advantages of strong anti-interference, high transmission efficiency and stable reliability. A typical structure of the double-core cable includes two electric cores, an inner insulation layer and an outer insulation layer. The inner insulation layer is wrapped around the circumference of each electric core, and the outer insulation layer is wrapped outside the two inner insulation layers.

[0043] The signals are transmitted in the electric cores, the inner insulation layer is used to avoid crosstalk of the signals transmitted by the two electric cores, and the outer insulation layer is used to avoid crosstalk between the cable and other cables.

[0044] With the development of signal transmission towards high frequency and high speed, the cable is required to have lower loss. The signal loss of the cable mainly includes conductor loss and insulation loss. The conductor loss is caused by the resistance of the electric core, which is also called resistance loss. The insulation loss is caused by the inner insulation layer and the outer insulation layer, which is also called dielectric loss. The dielectric loss accounts for 30% of the total loss.

[0045] The dielectric loss is mainly related to the dielectric constant (DK) and the dissipation factor (DF) of the insulation layer. For example, the lower the dielectric constant, the lower the dielectric loss, and the lower the dielectric loss.

[0046] Considering that the dielectric constant and the dielectric loss of air are relatively low, introducing air into the inner insulation layer and the outer insulation layer can reduce the dielectric loss of the inner insulation layer and the outer insulation layer.

[0047] In the prior art, in order to introduce air into the inner insulation layer and the outer insulation layer, the inner insulation layer is usually made by foaming process to form air holes in the inner insulation layer. The material of the outer insulation layer is generally expanded polytetrafluoroethylene (EPTFE). The EPTFE is in the form of a strip and is formed outside the inner insulation layer by wrapping process. The EPTFE itself has a microporous structure, so that the outer insulation layer formed by the EPTFE has air.

[0048] However, the microporous structure of each layer of EPTFE formed by the outer insulation layer of EPTFE penetrates the thickness of the EPTFE, which is reflected on the outer insulation layer. These microporous structures are distributed along the radial direction and are in communication with the external environment. This microporous structure will cause the cable to be not resistant to water vapor and be prone to moisture.

[0049] Moreover, the porosity of the outer insulation layer formed by EPTFE is too high, such as up to 65%, and the outer insulation layer with high porosity leads to the mechanical performance of the cable to be reduced. For example, the cable is applied in a bending scene, and the cable is prone to deformation in the bending, which affects the impedance of the inner core 1 of the cable to drop and discontinuity of the impedance to occur, and once the impedance of the inner core 1 is discontinuous, the signal transmission will be affected, for example, the conductor loss increases.

[0050] In addition, considering that the cable has application scenes such as bending, pressure bearing, and high temperature and humidity, the outer insulation layer needs to have certain mechanical strength and moisture-proof performance to avoid the discontinuity caused by the impedance drop to cause loss degradation. For example, the impedance drop of the outer insulation layer is greater than 5Ω during bending, and the loss degradation of the conductor is greater than 7%, which seriously affects the signal integrity (SI) performance of the cable, and further limits the further evolution of the product using the cable to 224G.

[0051] Therefore, the embodiment provides a cable, and the outer insulation layer of the cable has a plurality of hole structures, each hole structure is not communicated with the outer surface of the outer insulation layer in the radial direction, and belongs to a closed hole structure. The hole structure on the outer insulation layer is isolated from the external environment and can block water vapor, so that the cable is not prone to moisture.

[0052] As shown in FIG. 1, it is a cross-sectional schematic view of the cable shown in the embodiment. Referring to FIG. 1, the cable includes a plurality of inner cores 1, a first insulation layer 2, and a second insulation layer 3. The number of the inner cores 1 can be two, three, four, or more. The number of the first insulation layer 2 is equal to the number of the inner cores 1. For example, the circumferential direction of each inner core 1 is covered with the first insulation layer 2.

[0053] The number of the second insulation layer 3 is related to the number of the first insulation layer 2. For example, the second insulation layer 3 is covered in the circumferential direction outside the plurality of first insulation layers 2. As an example, as shown in FIG. 1, the number of the second insulation layer 3 is one, and the second insulation layer 3 is covered outside all the first insulation layers 2. As another example, the number of the second insulation layer 3 can also be multiple, and the number is less than the number of the first insulation layer 2, so that each second insulation layer 3 covers multiple first insulation layers 2 in the circumferential direction. For example, the number of the inner cores 1 is four, the circumferential direction of each inner core 1 is covered with the first insulation layer 2, and there are four first insulation layers 2, and each second insulation layer 3 is covered outside two first insulation layers 2.

[0054] In the embodiment, the number of the second insulation layer 3 is not limited to one or multiple, and for the convenience of introduction, the example of the second insulation layer 3 covered outside all the first insulation layers 2 is shown in FIG. 1.

[0055] The first insulation layer 2 is also called inner insulation layer because it is located inside the cable compared with the second insulation layer 3, and the second insulation layer 3 is also called outer insulation layer.

[0056] It should be noted that there can be a gap between the second insulation layer 3 and the first insulation layer 2. For example, as shown in FIG. 1, the second insulation layer 3 is sleeved outside the two first insulation layers 2, and the area surrounded by the second insulation layer 3 and the two first insulation layers 2 is not filled with insulation material but a gap. In another example, there can be no gap between the second insulation layer 3 and the first insulation layer 2. For example, as shown in FIG. 2, the second insulation layer 3 is sleeved outside the two first insulation layers 2, and the second insulation layer 3 is outside the first insulation layer 2. Whether there is a gap between the first insulation layer 2 and the second insulation layer 3 is mainly related to the mold for processing the second insulation layer 3, and the embodiment is not limited in this regard. In the drawings, the second insulation layer 3 is shown as a racetrack type.

[0057] As described above, in order to reduce the dielectric constant and dielectric loss of the insulation layer, it is necessary to introduce air into the insulation layer. For the first insulation layer 2, air is generally introduced into the first insulation layer 2 through a foaming process. For example, a foaming agent is added to the liquid or gel raw material for forming the first insulation layer 2, and the liquid or gel raw material with the foaming agent is then extruded through an extrusion mold to form the first insulation layer 2. Under the action of the foaming agent, many pores are formed in the first insulation layer 2. The pores are filled with air, so the pores in the first insulation layer 2 can also be called air holes (short for air holes).

[0058] In one example, the air holes in the first insulation layer 2 can be formed by physical foaming or chemical foaming. Physical foaming is a foaming method in which air holes are formed by the foaming agent itself. The foaming agent used is generally one or a mixture of several of carbon dioxide, nitrogen, butane, and freon. Chemical foaming is a foaming method in which air bubbles are formed by chemical reaction of the foaming agent. The foaming agent used is generally azobisdimethylamide, sodium bicarbonate, or magnesium hydroxide.

[0059] In one example, the second insulation layer 3 has a pore structure, and the pores of the pore structure are filled with air. Therefore, the pore structure of the second insulation layer 3 can also be called air holes (short for air holes). The pore structure 31 of the second insulation layer 3 is a closed pore structure. Specifically, the pore structure 31 in the second insulation layer 3 is not connected to the outer surface of the second insulation layer 3. The outer surface of the second insulation layer 3 is the surface that faces away from the first insulation layer 2 in the radial direction. Since the pore structure 31 of the second insulation layer 3 is not connected to the outer surface of the second insulation layer 3, the pore structure 31 is located inside the second insulation layer 3.

[0060] In an example, the hole structure 31 of the second insulation layer 3 is not communicated with the outer surface of the second insulation layer 3, which can be that all the hole structures 31 are not communicated with the outer surface, or that part of the hole structures 31 are not communicated with the outer surface and the other part of the hole structures 31 are communicated with the outer surface.

[0061] In an example, the hole structure 31 in the second insulation layer 3 can be formed by a coupling core process, for example, by designing a special structure of a mold, such as a mold having a coupling core structure (such as a strip-shaped protruding rib) for forming a coupling core hole, so that during the extrusion of the second insulation layer 3, the second insulation layer 3 having the coupling core hole is formed, and as shown in FIG. 3, which is a schematic view of the cross section of the cable along the axial direction, the hole structure 31 is a strip-shaped coupling core hole.

[0062] In an example, the strip direction of the hole structure 31 of the second insulation layer 3 is parallel to the length direction of the cable, for example, the center line of the hole structure 31 is parallel to the center line of the cable.

[0063] In an example, the hole structure 31 can pass through the entire length of the cable, for example, the two ends of the hole structure are located at the two ends of the cable, respectively. In another example, the hole structure 31 can also not pass through the length of the cable, for example, one end of the hole structure is located at the end of the cable, and the other end is located inside the cable, and for example, both ends of the hole structure are located inside the cable.

[0064] In an example, the hole structure 31 in the second insulation layer 3 is formed by a coupling core process, which can control the number of hole structures in the second insulation layer 3 by setting the number of coupling core structures of the mold, so that the number of hole structures in the second insulation layer 3 is adjustable, which is beneficial to balance the porosity and mechanical properties of the cable.

[0065] In an example, the hole structure formed by the coupling core process can also control the arrangement mode of the plurality of hole structures in the second insulation layer 3 by controlling the arrangement mode of the coupling core structure on the mold.

[0066] In an example, in the scheme of forming the hole structure in the second insulation layer 3 by the coupling core process, the specific shape and size of the hole structure in the second insulation layer 3 can also be controlled by setting the cross-sectional shape and size of the coupling core structure of the mold, so that the shape of the hole structure in the second insulation layer 3 is controllable. For example, the cross-sectional shape of the hole structure 31 of the second insulation layer 3 can be a circular hole shape as shown in FIG. 1, or a polygonal shape, or a sector or an oval shape, wherein the specific shape of the hole structure is not limited in the present embodiment, and the circular hole structure is exemplified in the drawings.

[0067] In addition, the scheme of forming the hole structure in the second insulating layer 3 by the coupling core process has high production efficiency and is suitable for mass production of the cable. Moreover, the shape, number and arrangement of the hole structure can be accurately controlled, so that the hole structure 31 in the second insulating layer 3 is controllable.

[0068] Through simulation and experimental tests, in the scheme of forming the hole structure in the second insulating layer 3 by the coupling core process, the dielectric constant of the second insulating layer 3 can be controlled to be between 1.0 and 2.1.

[0069] In another example, the hole structure 31 in the second insulating layer 3 can also be formed by a foaming process. For example, a foaming agent is added to the liquid or gel raw material for forming the second insulating layer 3, and the liquid or gel raw material with the foaming agent is extruded by an extrusion die to form the second insulating layer 3. Under the action of the foaming agent, many pores are formed in the second insulating layer 3, which are the hole structure 31. As shown in FIG. 4, which is a cross-sectional view of the hole structure 31 formed in the second insulating layer 3 by the foaming process, the small dots in the second insulating layer 3 in FIG. 4 represent the hole structure. Since the hole diameter of the hole structure 31 formed by the foaming agent is relatively small and irregular, the hole structure is schematically shown by small black dots in FIG. 4.

[0070] In an example, in the scheme of forming the hole structure 31 in the second insulating layer 3 by the foaming process, the number of the hole structure in the second insulating layer 3 can also be controlled by controlling the content of the foaming agent. Since the distribution of the foaming agent in the second insulating layer 3 cannot be controlled, the hole structure formed by the foaming process is generally irregularly distributed in the second insulating layer 3. However, no matter how the hole structure is distributed in the second insulating layer, the hole structure 31 is not in communication with the outer surface of the second insulating layer 3, so that the hole structure is a closed hole structure.

[0071] Through simulation and experimental tests, in the scheme of forming the hole structure in the second insulating layer 3 by the coupling core process, the dielectric constant of the second insulating layer 3 can be controlled to be between 1.3 and 2.1.

[0072] It should be noted that, since the present embodiment is mainly related to the characteristics of the hole structure in the second insulating layer 3, the pores in the first insulating layer 2 are not shown in the drawings.

[0073] It should be noted that the pores in the first insulating layer 2 can also be formed by the coupling core process. The specific forming process can be referred to the description of forming the hole structure in the second insulating layer 3 by the coupling core process described above, which will not be described here.

[0074] As described above, the hole structure in the second insulating layer 3 is formed by a coupling core process or a foaming process, so the material of the second insulating layer 3 does not need to use EPTFE with a micro-porous structure, and the material of the second insulating layer 3 can be a polymer with low dielectric constant and low dielectric loss.

[0075] For example, the material of the second insulating layer 3 can be a perfluorinated polymer or a polyolefin polymer. Specifically, the material of the second insulating layer 3 can be at least one of fluorinated ethylene propylene (FEP), polyfluoroalkoxy (PFA), polyethylene (PE), polypropylene (PP), copolymers of cycloolefin (COC), and poly-4-methyl-1-pentene (TPX).

[0076] In an example, as shown in FIG. 5, which is a schematic view of a cross section of the cable, referring to FIG. 5, the cable further includes a shielding layer 4, which is wrapped in the circumferential direction outside the plurality of second insulating layers 3, for example, wrapped outside all the second insulating layers 3. The shielding layer 4 is generally a metal mesh structure, which is used to shield electromagnetic interference between the cable and other cables or devices.

[0077] Continuing to refer to FIG. 5, the cable further includes a protective layer 5, which can also be referred to as a Mylar layer, wrapped in the circumferential direction outside the shielding layer 4, which protects the shielding layer 4 from corrosion or oxidation.

[0078] Based on the above, the circumferential direction of each battery cell 1 is wrapped with a first insulating layer 2, wherein each first insulating layer 2 is wrapped in the circumferential direction of the battery cell 1 by an extrusion process, and the first insulating layer 2 has a large number of pores, wherein the pores in the first insulating layer 2 are formed by a foaming process to increase the porosity of the first insulating layer 2. The circumferential direction of the plurality of first insulating layers 2 is wrapped with a second insulating layer 3, which can be wrapped outside the plurality of first insulating layers 2 by an extrusion process, and the second insulating layer 3 also has a plurality of hole structures 31 distributed therein, wherein the hole structure of the second insulating layer 3 can be formed by a coupling core process or a foaming process to increase the porosity of the second insulating layer 3. All the second insulating layers 3 are wrapped with a shielding layer 4 and a protective layer 5 in turn to form a multi-core cable.

[0079] The hole structure in the second insulating layer 3 is not connected with the outer surface of the second insulating layer 3 and is a closed hole structure in the radial direction, which can effectively block water vapor and prevent the cable from being damp, thereby prolonging the service life of the cable.

[0080] The hole structure of the second insulation layer 3 can be formed by a coupling core structure of an extrusion die, so that the number, shape and size of the hole structure of the second insulation layer 3 are controllable, and the arrangement in the second insulation layer 3 is controllable, which is beneficial to balance the porosity and mechanical properties of the cable, so that the cable has both low dielectric loss and good mechanical properties.

[0081] For example, the loss of such a cable is less than 10% in a double 85 test, wherein the double 85 test is a test under the condition that the temperature is set to 85 degrees and the humidity is set to 85%.

[0082] In an example, the first insulation layer 2 introduces air through a foaming process, and the second insulation layer 3 introduces air through a coupling core process or a foaming process, so that the first insulation layer 2 and the second insulation layer 3 can be processed by an extrusion process, and the extrusion speed is larger than the wrapping speed in the wrapping technology, such as the extrusion speed can be greater than 50 meters per second, which is beneficial to speed up the production of the cable and improve the production efficiency of the cable.

[0083] In the embodiments of the present disclosure, a plurality of hole structures are arranged in the second insulation layer of the cable, which are not communicated with the outer surface of the second insulation layer and belong to closed hole structures in the radial direction, which can effectively block water vapor, so that the cable is not easy to be damp, and the service life of the cable is prolonged. Moreover, the hole structure in the second insulation layer can be formed by a coupling core process, and by controlling the number of the coupling core structure of the die for forming the second insulation layer, the number of the hole structure in the second insulation layer can be controlled, and then the porosity of the second insulation layer can be adjusted, which is beneficial to balance the porosity and mechanical properties of the second insulation layer, so that the cable meets both low dielectric loss and good mechanical properties.

[0084] The terms used in the embodiments of the present disclosure are used only to explain embodiments of the present disclosure and not to limit the present disclosure. Unless otherwise defined, the terms used in the embodiments of the present disclosure should be interpreted as having a meaning that is consistent with a meaning in the related art. The terms "first", "second", and the like used in the specification and claims of the present disclosure are used to distinguish the names of the components from one another, and do not limit the components in sequence, number, or importance. Also, the terms "one", "another", or the like used in the specification and claims of the present disclosure are not limited to "one" or "another" but are used to indicate at least one. The terms "include", "comprise", and the like used in the specification and claims of the present disclosure mean that the elements or objects listed in the "include" or "comprise" are included in the "include" or "comprise" but do not exclude other elements or objects not listed. The terms "upper", "lower", "left", "right", and the like are used to indicate relative positions only, and when the absolute positions of the described objects are changed, the relative positions can also be changed accordingly. "Multiple" means two or more, unless otherwise specified.

[0085] The above-described embodiments are merely illustrative of the present disclosure and do not limit the present disclosure. Any modification, equivalent replacement, improvement, and the like made within the principles of the present disclosure should be included in the scope of the present disclosure.

Claims

1. A cable, characterized by The cable comprises a plurality of electric cores (1), a first insulating layer (2) and a second insulating layer (3); The first insulating layer (2) is coated on the circumference of each electric core (1), and the second insulating layer (3) is coated outside the plurality of first insulating layers (2); The second insulating layer (3) has a plurality of hole structures (31), and the hole structures (31) are not communicated with the outer surface of the second insulating layer (3), wherein the outer surface of the second insulating layer (3) is the surface facing away from the first insulating layer (2) in the radial direction.

2. The cable of claim 1, wherein, The hole structures (31) are in the shape of strips, and the strip direction of the hole structures (31) is parallel to the length direction of the cable.

3. The electrical cable according to claim 1 or 2, characterized in that, The hole structures (31) are coupling core holes formed by a coupling core process.

4. The cable of claim 3, wherein, The cross section of the hole structures (31) is in the shape of a polygon, a circle, an ellipse or a sector.

5. The cable of claim 1, wherein, The hole structures (31) are formed in the second insulating layer (3) by a foaming process.

6. The cable according to any one of claims 1 to 5, characterized in that The second insulating layer (3) is formed by an extrusion process.

7. A cable according to any one of claims 1 to 6, characterised in that, The material of the second insulating layer (3) is a perfluoropolymer or a polyolefin polymer.

8. The cable of claim 7, wherein, The material of the second insulating layer (3) is at least one of polyfluoroethylene propylene FEP, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer PFA, polyethylene PE, polypropylene PP, cyclic olefin copolymer COC and poly-4-methyl-1-pentene TPX.

9. The cable according to any one of claims 1 to 8, characterized in that The cable further comprises a shielding layer (4) coated outside the second insulating layer (3) in the circumferential direction.

10. The cable of claim 9, wherein, The cable further comprises a protective layer (5) coated outside the shielding layer (4) in the circumferential direction.

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