A full dry water-blocking type high shielding long-distance symmetrical communication cable

Abstract

The application discloses a full-dry water-blocking type high-shielding long-distance symmetrical communication cable, which comprises a twisted cable core, a first water-blocking layer, a shielding layer, an inner sheath, a second water-blocking layer, an armoring layer and an outer sheath which are sequentially arranged from inside to outside; the twisted cable core is twisted into a cable by filling an environmental protection expansion type water-blocking filling rope among a plurality of signal twisted groups and a plurality of low-frequency four-wire groups; each group of signal twisted groups and each group of low-frequency four-wire groups are twisted by a plurality of insulated single wires, and the twisted groups are bound with environmental protection expansion type water-blocking yarns; and the twisted pitches of each group of signal twisted groups and each group of low-frequency four-wire groups are different. The symmetrical communication cable adopts a brand-new full-dry water-blocking structure design, discards the traditional oil paste filling mode, and has the advantages of reliable water-blocking, convenient production and construction, good environmental protection, stable structure, efficient transmission and controllable cost, and can completely solve the core defects of the prior art.

Description

Technical Field

[0001] This invention relates to the field of communication cable technology, specifically to a fully dry, water-resistant, high-shield, long-distance symmetrical communication cable. Background Technology

[0002] As the core carrier of cross-regional communication, long-distance symmetrical communication cables must withstand long-term water vapor erosion, soil pressure, and temperature fluctuations in the laying environment. Their water-blocking performance and signal transmission stability directly determine communication quality. Currently, the mainstream long-distance symmetrical communication cables in the industry mainly adopt a "grease-filled" water-blocking structure, which blocks water vapor penetration by filling the gaps between the cable cores with petroleum-based water-blocking grease. This method has the following shortcomings: Firstly, the water-blocking performance has shortcomings. Existing long-distance symmetrical communication cables mostly use grease-filled water-blocking. The water-blocking grease is fluid and easily solidifies and cracks in low-temperature environments and overflows in high-temperature environments. After long-term use, the water-blocking performance deteriorates significantly, especially in laying areas with high groundwater levels, where water ingress into the cable core can easily lead to excessive signal attenuation. At the same time, the grease filling process is cumbersome. During production, the amount and pressure of grease filling must be precisely controlled. Residual grease must be cleaned during subsequent cable splicing, which not only increases construction time but also easily affects the splicing quality and causes low insulation problems due to incomplete cleaning.

[0003] Secondly, it has poor environmental performance and deviates from the trend of green communication development. The petroleum-based water-blocking grease used in existing long-distance symmetrical communication cables is a non-degradable material, which can easily cause environmental pollution during the recycling of waste cables, contradicting the current industry's green, low-carbon, and environmentally friendly development concept.

[0004] Third, the structure has poor adaptability and insufficient synergy of the water-blocking system. The water-blocking structure has poor compatibility with the wire pair structure and sheath structure. The filling material between wire pairs is mostly ordinary non-water-blocking material, which cannot completely fill the gap between wire pairs and easily forms a water vapor penetration channel. At the same time, the filling material has poor compatibility with each structural layer, and is prone to aging and falling off after long-term use, which damages the overall structural stability of the cable and cannot adapt to the complex working conditions such as soil compression, mechanical pulling, and drastic changes in temperature and humidity during long-distance laying, further aggravating the risk of water-blocking failure.

[0005] Fourth, signal transmission stability is affected by the water-blocking structure. Uneven filling of the grease can easily lead to incomplete filling of the gaps inside the cable core, resulting in poor structural stability and easy drift of electrical parameters. At the same time, the physical and chemical properties of the grease can indirectly affect the insulation performance of the wire pairs as the environment changes, leading to signal attenuation and distortion during long-distance transmission, making it difficult to meet the transmission requirements of long-distance communication.

[0006] In summary, existing long-distance symmetrical communication cables have significant shortcomings in terms of water-blocking performance, environmental friendliness, structural adaptability, and signal transmission stability. There is an urgent need to develop a long-distance symmetrical communication cable with a fully dry water-blocking core that is environmentally friendly, convenient, structurally stable, reliable in transmission, and cost-controllable, so as to completely solve the series of problems caused by grease filling and meet the actual needs of long-distance communication projects. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned deficiencies of existing long-distance symmetrical communication cables by providing a fully dry, water-blocking, high-shield long-distance symmetrical communication cable. This cable adopts a novel fully dry, water-blocking structural design, abandoning the traditional grease-filling method. It has advantages such as reliable water blocking, convenient production and construction, good environmental performance, stable structure, high transmission efficiency, and controllable cost, and can completely solve the core shortcomings of existing technologies.

[0008] This invention is achieved through the following technical solution: This invention provides a fully dry, water-blocking, high-shield, long-distance symmetrical communication cable, comprising, from the inside out, a stranded cable core, a first water-blocking layer, a shielding layer, an inner sheath, a second water-blocking layer, an armor layer, and an outer sheath. The stranded cable core is formed by twisting multiple signal twisted pairs and multiple low-frequency four-wire groups together with environmentally friendly, expandable water-blocking filler rope. Each signal twisted pair and each low-frequency four-wire group is formed by twisting multiple insulated single wires together, and after twisting, they are wrapped with environmentally friendly, expandable water-blocking yarn. The twisting pitch of each signal twisted pair and each low-frequency four-wire group is different.

[0009] As a further embodiment of the present invention, the twisting pitch of the signal twisted pair is set to 70mm-110mm, the twisting pitch of the low-frequency four-wire group is set to 100mm-260mm, and the twisting pitch difference between adjacent signal twisted pairs, adjacent low-frequency four-wire groups, and between signal twisted pairs and low-frequency four-wire groups is P, satisfying 20mm≤P≤25mm.

[0010] As a further embodiment of the present invention, the first water-blocking layer comprises, from the inside out, a double-layer environmentally friendly expandable water-blocking strip, a polyethylene protective layer, and a single-layer environmentally friendly expandable water-blocking strip; the double-layer environmentally friendly expandable water-blocking strip is wrapped around the outside of the stranded cable core, the polyethylene protective layer is extruded around the outside of the double-layer environmentally friendly expandable water-blocking strip and has a thickness of 0.5mm-0.6mm, the single-layer environmentally friendly expandable water-blocking strip is wrapped around the outside of the polyethylene protective layer, and the overlap rate of the wrapping is ≥50%.

[0011] As a further embodiment of the present invention, the shielding layer is made of industrial pure aluminum plate with a thickness of 1.7mm-1.8mm and a purity of ≥99.7% through seamless welding, and is wrapped around the outside of the first water-blocking layer, with a shielding effectiveness of ≥85dB, so as to shield external electromagnetic interference.

[0012] As a further embodiment of the present invention, the inner sheath is made of low-smoke halogen-free polyolefin material extruded and wrapped around the outside of the shielding layer, and the thickness of the inner sheath is 1.0mm-1.3mm, and the extrusion temperature is 120℃-180℃.

[0013] As a further embodiment of the present invention, the second water-blocking layer includes an environmentally friendly expandable water-blocking strip and an environmentally friendly expandable water-blocking yarn arranged sequentially from the inside to the outside; the environmentally friendly expandable water-blocking strip is tightly wrapped around the outside of the inner sheath, and the environmentally friendly expandable water-blocking yarn is evenly distributed between the environmentally friendly expandable water-blocking strip and the armor layer, filling the gap between the two to ensure that there are no gaps or voids.

[0014] As a further embodiment of the present invention, the armor layer adopts a double-layer high-permeability steel strip armor gap wrapping, the steel strip thickness is 0.50mm-0.52mm, and is wrapped around the outside of the second water-blocking layer through a reverse gap wrapping process, with the wrapping gap being less than 30% and the wrapping angle controlled within the range of α±5°, so that the armor layer generates a continuous radial binding stress of 0.5MPa-1.2MPa on the inner second water-blocking layer.

[0015] As a further aspect of the present invention, the outer side of the armor layer is filled with environmentally friendly, expandable, water-resistant yarn to wrap and fill the gaps in the armor layer, ensuring that there are no gaps or voids.

[0016] As a further embodiment of the present invention, the outer sheath is made of weather-resistant, low-smoke, halogen-free polyolefin material, which is extruded and wrapped around the outside of the armor layer, and the thickness of the outer sheath is 2.0mm-2.2mm, with the extrusion temperature controlled at 110℃-130℃.

[0017] As a further embodiment of the present invention, the insulated single wires in the signal twisted pair and the low-frequency four-wire group each include a conductor and an outer insulating layer; the conductor diameter of the insulated single wire in the signal twisted pair is set to 0.704mm-0.705mm, and its insulation layer is made of solid polyethylene, with an inner sheath of low-density polyethylene and an outer sheath of high-density polyethylene; the conductor diameter of the insulated single wire in the low-frequency four-wire group is set to 0.903mm-0.905mm, and its insulation layer is made of physically foamed polyolefin, with an inner sheath of low-density polyethylene, an outer sheath of high-density polyethylene, and a foaming layer of high-density foamed polyolefin.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Excellent water-blocking performance, achieving long-term stable water blocking in a completely dry manner: By constructing a three-level completely dry water-blocking structure of "line-to-line micro water blocking + first water blocking layer + second water blocking layer", a double core water-blocking barrier is formed. No grease is required. When exposed to water, the water-blocking material expands rapidly (expansion ratio ≥300%), which can instantly block all water vapor penetration channels. This completely solves the problems of solidification, cracking, overflow, and performance degradation of existing grease-based water blocking materials under high and low temperature environments. Even in harsh laying areas with high groundwater levels, it can ensure that the cable core is dry for a long time, and the water-blocking performance is stable throughout the entire life cycle. This fundamentally avoids problems such as signal attenuation and insulation failure caused by water entering the cable core.

[0019] 2. Significantly simplified production and construction, with improved efficiency and reliability: The all-dry water-blocking structure eliminates the need for grease filling, eliminating the need for precise control of grease filling amount and pressure during production. This simplifies production processes, reduces production equipment and process control costs, and eliminates grease pollution, resulting in significantly improved production efficiency. During laying and splicing, there is no grease overflow or the need to clean residual grease, greatly reducing construction time and improving construction efficiency. At the same time, it avoids problems such as low insulation and poor splicing quality caused by incomplete grease cleaning, ensuring the overall performance reliability of the cable after construction and splicing.

[0020] 3. Outstanding environmental performance, in line with the core trend of green communication development: All water-blocking materials (expandable water-blocking filler rope, water-blocking tape, water-blocking yarn) are all dry, environmentally friendly and biodegradable, with no petroleum-based water-blocking grease. At the same time, the inner and outer sheaths are made of low-smoke halogen-free polyolefin environmentally friendly materials, and no harmful pollutants are generated throughout the entire life cycle of the cable. When the waste cable is recycled, all kinds of materials can be degraded or recycled and reused without environmental pollution, which fully complies with the current industry's green, low-carbon and environmentally friendly development concept.

[0021] 4. Stable structure and strong environmental adaptability; water-blocking performance is unaffected by working conditions: The all-dry water-blocking material is highly compatible with each structural layer of the cable. The filler rope, water-blocking tape, and water-blocking yarn achieve full and dense filling of the gaps inside the cable. Each layer is tightly bonded through extrusion, wrapping, and pressing processes, without gaps or loosening. The armor layer presses the second water-blocking layer, providing both mechanical protection and improving the water-blocking and sealing effect. The outer sheath has a wide temperature range of -40℃ to 80℃ and can adapt to various complex laying scenarios such as direct burial, pipeline, and overhead installation. It resists external erosion such as soil compression, rainwater immersion, and ultraviolet radiation, ensuring that the water-blocking structure is not damaged and the water-blocking performance does not decrease under various harsh working conditions. The overall cable structure is stable and has a long service life.

[0022] 5. Stable and low-loss signal transmission, with synergistic improvement in water blocking and transmission performance: The compact design of the all-dry water-blocking structure avoids problems such as unstable cable core structure and electrical parameter drift caused by uneven grease filling, ensuring long-term stable electrical performance of the cable; at the same time, by combining high-purity TR-type conductors, differentiated insulation layers, and unequal pitch stranding design, signal transmission loss is effectively reduced and crosstalk interference is reduced, achieving long-distance low-loss and low-distortion signal transmission; and the all-dry water-blocking structure and transmission structure do not interfere with each other, but rather further improve transmission stability through structural compaction, achieving a synergistic unity of "reliable water blocking" and "efficient transmission".

[0023] 6. Controllable cost, combining practicality and economy: The fully dry water-blocking material is readily available and the production process is mature, eliminating the need for special equipment and process control for grease filling, thus reducing manufacturing costs; the cable structure design is simple, and the weight and outer diameter are reasonably controlled, facilitating transportation and laying, reducing logistics and construction costs; at the same time, the fully dry water-blocking performance is stable for a long time, reducing the cost of cable maintenance and replacement, enabling large-scale production, and making it widely used in various long-distance communication projects, combining strong practicality and economy. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the fully dry, water-resistant, highly shielded long-distance symmetrical communication cable of the present invention.

[0025] The attached diagram shows the markings and corresponding component names: 1-Low-frequency four-wire group, 11-Polyolefin insulated single wire with foamed plastic coating, 12-Environmentally friendly expandable water-blocking yarn, 2-Signal twisted pair group, 21-Solid polyethylene insulated single wire, 22-Environmentally friendly expandable water-blocking yarn, 3-Environmentally friendly expandable water-blocking filler rope, 41-Environmentally friendly expandable water-blocking tape, 42-Polyethylene protective layer, 43-Environmentally friendly expandable water-blocking tape, 5-Shielding layer, 6-Inner sheath, 71-Environmentally friendly expandable water-blocking tape, 72-Environmentally friendly expandable water-blocking yarn, 8-Armor layer, 81-Environmentally friendly expandable water-blocking yarn, 9-Outer sheath. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0028] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0031] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0032] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0033] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0034] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0035] Existing long-distance symmetrical communication cables suffer from significant deficiencies in water-blocking performance, environmental friendliness, structural adaptability, and signal transmission stability. There is an urgent need to develop a long-distance symmetrical communication cable that is environmentally friendly, convenient, structurally stable, reliable in transmission, and cost-effective, with a fully dry water-blocking technology as its core. This would completely solve the problems associated with grease filling and meet the practical needs of long-distance communication engineering. Therefore, the applicant proposes a fully dry water-blocking long-distance symmetrical communication cable, using fully dry water-blocking technology as its core to address the pain points of existing technologies and solve the following technical problems: (1) Solve the problem that existing water-blocking grease is prone to solidification, cracking and overflow in high and low temperature environments due to its fluidity, and its water-blocking performance deteriorates after long-term use. In areas with high groundwater levels, it is also prone to water ingress into the cable core and excessive signal attenuation. The solution is to achieve fully dry, efficient and long-lasting water blocking of the cable and ensure the stability of signal transmission.

[0036] (2) Solve the problem of complicated grease filling process, which requires precise control of filling amount and pressure during production, and the need to clean residual grease during cable splicing, which increases construction time. At the same time, incomplete cleaning can affect splicing quality and cause low insulation problems. The all-dry structure simplifies the production and construction process, and improves splicing reliability and construction efficiency.

[0037] (3) To solve the problem that petroleum-based water-blocking grease is non-degradable and easily causes environmental pollution when waste cables are recycled, the application of all-dry environmentally friendly water-blocking materials can improve the overall environmental performance of cables and meet the industry's green and low-carbon development needs.

[0038] (4) To solve the problem that the existing cable water-blocking structure is not sufficiently coordinated with the structure of the wire pair and sheath, which easily forms water vapor penetration channels and the structure is prone to aging and damage, an integrated system that is fully dry water-blocking and deeply adapted to the overall cable structure is constructed to improve the stability and environmental adaptability of the cable structure and adapt to long-distance complex laying conditions.

[0039] (5) To solve the problem of unstable cable core structure and electrical parameter drift caused by uneven filling of grease, which in turn affects the stability of signal transmission, the cable core structure is stabilized by the compact design of the all-dry water-blocking structure, reducing signal transmission loss and meeting the needs of long-distance low-interference communication.

[0040] Please refer to Figure 1 The embodiment of this application provides a fully dry, water-blocking, high-shield, long-distance symmetrical communication cable, comprising, from the inside out, a stranded cable core, a first water-blocking layer, a shielding layer 5, an inner sheath 6, a second water-blocking layer, an armor layer 8, and an outer sheath 9; the stranded cable core is formed by stranding multiple signal twisted pairs 2 and multiple low-frequency four-wire groups 1 together with environmentally friendly expansion-type water-blocking filler rope 3. Each signal twisted pair 2 and each low-frequency four-wire group 1 is formed by stranding multiple insulated single wires, and after stranding, they are respectively wrapped with environmentally friendly expansion-type water-blocking yarn 22 and 12, and the stranding pitch of each signal twisted pair 2 and each low-frequency four-wire group 1 is different.

[0041] In this application, the stranded cable core is formed by twisting multiple signal twisted pairs 2 and multiple low-frequency four-wire groups 1 clockwise, with a stranding pitch of 500-550mm. During the stranding process, environmentally friendly expanding water-blocking filler rope 3 is used to fix the wire pair positions, reduce capacitance imbalance, and achieve dense filling of the gaps between the stranded layers, blocking the lateral penetration path of water vapor. Simultaneously, since the stranding pitches of each signal twisted pair 2 and each low-frequency four-wire group 1 are different, the coupling design of unequal-pitch stranding and water-blocking yarn allows the water-blocking yarn to self-lock and anchor onto the wire pair surface, forming a structurally stable and uniformly distributed initial water-blocking layer. In this embodiment, the symmetrical communication cable layers are tightly bonded and work synergistically to form a complete structure with a fully dry double water-blocking barrier as its core, achieving the technical goals of long-term water blocking, structural stability, and low-loss transmission.

[0042] According to some embodiments of this application, the insulated single wires in both the signal twisted pair group 2 and the low-frequency four-wire group 1 include a conductor and an outer insulating layer. The conductors are all TR-type soft round copper wires with a copper wire purity ≥99.9%, ensuring low signal transmission loss. Specifically, the diameter of the insulated single wire conductor in the low-frequency four-wire group 1 is set to 0.903-0.905mm for low-frequency signal transmission; the diameter of the insulated single wire conductor in the signal twisted pair group 2 is set to 0.704-0.705mm for conventional signal transmission. The two types of conductors are respectively wrapped with insulating layers to form independent insulated cores, laying the foundation for subsequent pair twisting, cabling, and adaptation to a fully dry, water-blocking structure.

[0043] The insulation layers of the two types of conductors employ differentiated insulation designs to adapt to the transmission requirements of both types of conductors, while simultaneously improving the insulation performance between wire pairs and avoiding the risk of moisture penetration indirectly caused by insulation failure. Specifically, the low-frequency four-wire group 1 uses a single wire 11 with physically foamed polyolefin insulation, featuring an inner sheath of low-density polyethylene, an outer sheath of high-density polyethylene, and a foam layer of high-density foamed polyolefin, combining excellent insulation performance with low transmission loss characteristics. The signal twisted pair group 2 uses a solid polyethylene insulated single wire 21, with an inner sheath of low-density polyethylene and an outer sheath of high-density polyethylene, ensuring the stability of conventional signal transmission.

[0044] Among them, the outer insulation layer of the conductor of the low-frequency four-wire group 1 has a thickness of 0.72-0.75mm, and the extrusion temperature is controlled at 210-220℃; the outer insulation layer of the conductor of the signal twisted pair group 2 has a thickness of 0.42-0.52mm, and the extrusion temperature is controlled at 250-260℃, so as to ensure that the insulation layer is smooth and round, without pinholes or damage, to achieve effective insulation between wire pairs, while avoiding the formation of water vapor penetration channels due to insulation layer damage.

[0045] According to some embodiments of this application, the twisting pitch of the signal twisted pair 2 is set to 70mm-110mm, the twisting pitch of the low-frequency four-wire group 1 is set to 100mm-260mm, and the twisting pitch difference between adjacent signal twisted pairs 2, adjacent low-frequency four-wire groups 1, and between signal twisted pairs 2 and low-frequency four-wire groups 1 is P, which satisfies 20mm≤P≤25mm.

[0046] In this symmetrical communication cable, the twisting pitch of each signal pair group 2 and each low-frequency four-wire group 1 is different. That is, the wire pair layers adopt an unequal pitch twisting design, combining two types of conductors for separate twisting, effectively offsetting the capacitance imbalance between wire pairs and reducing crosstalk interference. Research has found that the design parameters of the unequal pitch twisting have a crucial coupling relationship with the wrapping effect of the water-blocking yarn; the difference in twisting pitch directly affects the adhesion stability of the water-blocking yarn on the surface of the wire pairs after twisting.

[0047] Specifically, the twist pitch of each signal pair group 2 is set to 70-110mm, and the twist pitch of each low-frequency four-wire group 1 is set to 100-260mm. Furthermore, the difference in twist pitch between adjacent signal pair groups 2, adjacent low-frequency four-wire groups 1, and between signal pair groups 2 and low-frequency four-wire groups 1 is controlled to be 20mm-25mm. Within this range, a specific texture is formed on the surface of the wire pairs. This texture, together with the environmentally friendly expandable water-blocking yarn, forms a self-locking anchoring effect under the wrapping tension, ensuring that the water-blocking yarn adheres tightly to the surface of the wire pairs and is not prone to slippage or loosening.

[0048] Experiments have shown that when the stranding pitch difference is less than 15 mm, the surface of the wire pair is too smooth, and the water-blocking yarn is prone to longitudinal slippage under the stranding tension, resulting in uneven winding density and local gaps. When the stranding pitch difference is greater than 25 mm, the surface of the wire pair is excessively twisted, and the water-blocking yarn is prone to embedding into the insulation layer, causing insulation damage or breakage of the water-blocking yarn. Only within the above-mentioned optimal parameter range can the water-blocking yarn form a stable and dense micro-water-blocking barrier, initially blocking water vapor penetration along the line gaps, and achieving a deep coupling design of "stranding structure parameters - water-blocking process parameters".

[0049] According to some embodiments of this application, the first water-blocking layer includes a double-layer environmentally friendly expandable water-blocking tape 41, a polyethylene protective layer 42, and a single-layer environmentally friendly expandable water-blocking tape 43 arranged sequentially from the inside to the outside; the double-layer environmentally friendly expandable water-blocking tape 41 is wrapped around the outside of the stranded cable core, the polyethylene protective layer 42 is extruded around the outside of the double-layer environmentally friendly expandable water-blocking tape 41 and has a thickness of 0.5mm-0.6mm, and the single-layer environmentally friendly expandable water-blocking tape 43 is wrapped around the outside of the polyethylene protective layer 42, and the overlap rate of the wrapping is ≥50%.

[0050] This symmetrical communication cable forms the first fully dry and efficient water-blocking barrier by overlapping two layers of water-blocking tape (overlap rate ≥ 50%) around the stranded cable core, extruding a 0.5-0.6mm thick polyethylene protective layer 42 around the water-blocking tape, and then overlapping another layer of water-blocking tape (overlap rate ≥ 50%) around the protective layer. This works in conjunction with the line-pair level water-blocking yarn to achieve all-round water blocking inside the cable core.

[0051] According to some embodiments of this application, the shielding layer 5 is made of industrial pure aluminum plate with a thickness of 1.7mm-1.8mm and a purity of ≥99.7% through seamless welding, and is tightly wrapped around the outside of the first water-blocking layer without seams or damage. The shielding effectiveness is ≥85dB, which can effectively shield external electromagnetic interference. It can meet the requirements of low-speed data signal transmission with a transmission rate of ≥2Mbit / s without the need for additional shielding layer 5, thereby reducing the outer diameter of the cable and reducing the weight.

[0052] According to some embodiments of this application, the inner sheath 6 is made of low-smoke halogen-free polyolefin material extruded and wrapped around the outside of the shielding layer 5, and the thickness of the inner sheath 6 is 1.0mm-1.3mm, with an extrusion temperature of 120℃-180℃. This inner sheath 6 forms a sealing barrier, preventing moisture from penetrating inwards, protecting the first water-blocking barrier and the cable core structure, and providing a smooth and firm adhesion base for the outer second water-blocking layer.

[0053] According to some embodiments of this application, the second water-blocking layer includes an environmentally friendly expandable water-blocking tape 71 and an environmentally friendly expandable water-blocking yarn 72 arranged sequentially from the inside to the outside; the environmentally friendly expandable water-blocking tape 71 is tightly wrapped around the outside of the inner sheath 6, and the environmentally friendly expandable water-blocking yarn 72 is evenly distributed between the environmentally friendly expandable water-blocking tape 71 and the armor layer 8, filling the gap between the two to ensure that there are no gaps or voids.

[0054] The second water-blocking layer is located between the inner sheath 6 and the armor layer 8, serving as the cable's second core all-dry water-blocking barrier. Together with the first water-blocking barrier outside the stranded cable core, it forms a dual all-dry water-blocking system. The second water-blocking layer employs a composite structure of "water-blocking tape + water-blocking yarn." The water-blocking tape is made of expandable polyolefin, with a thickness of 0.2-0.3 mm, and is tightly wrapped around the outside of the inner sheath 6. The water-blocking yarn is evenly distributed between the water-blocking tape and the armor layer 8, filling the gaps and ensuring no gaps. Both the water-blocking tape and the water-blocking yarn are all-dry, environmentally friendly, and biodegradable materials, requiring no grease. They adhere tightly to the inner sheath 6 and the armor layer 8, rapidly expanding upon contact with water to seal all moisture penetration channels, ensuring the cable core remains dry for extended periods.

[0055] The "first water-blocking layer" and "second water-blocking layer" constructed in this application have a clear functional division and quantitative coordination relationship: they respectively constitute the first water-blocking barrier (outside the stranded cable core) and the second water-blocking barrier (outside the inner sheath 6). The second water-blocking barrier intercepts ≥95% of conventional water vapor intrusion, and a small amount of water vapor that penetrates the second water-blocking barrier (≤5%) will trigger the rapid expansion of the first water-blocking barrier. The expansion volume of the second water-blocking barrier is designed to be 1.5-2.0 times the volume of the annular gap of the armor layer 8, ensuring that even if the first water-blocking barrier fails partially, the expanded water-blocking material can still completely seal the infiltration channel. Simulation tests show that the overall water-blocking efficiency of the two-stage water-blocking layer is ≥99.9%, and remains stable throughout its entire life cycle.

[0056] According to some embodiments of this application, the armor layer 8 is wrapped with a double-layer high-permeability steel strip with a gap. The steel strip thickness is 0.50mm-0.52mm. It is wrapped around the outside of the second water-blocking layer using a reverse gap wrapping process, with a wrapping gap of less than 30% and a wrapping angle controlled within the range of α±5°. This allows the armor layer 8 to generate a continuous radial binding stress of 0.5MPa-1.2MPa on the inner second water-blocking layer. Environmentally friendly expandable water-blocking yarn 81 is then used to wrap and fill the wrapping gap of the armor layer 8 on the outside, ensuring no gaps remain. The armor layer 8 is tightly fitted to the second water-blocking layer, providing strong mechanical protection to prevent damage to the water-blocking layer, inner shielding layer 5, and internal structure caused by compression and pulling during cable laying. Furthermore, through the synergistic design of "armor-assisted sealing," a deep integration of mechanical protection and enhanced water-blocking efficiency is achieved, resisting the erosion of the water-blocking structure by the external environment.

[0057] According to some embodiments of this application, the outer sheath 9 is made of weather-resistant, low-smoke, halogen-free polyolefin material, which is extruded and wrapped around the outside of the armor layer 8. The outer sheath 9 has a thickness of 2.0mm-2.2mm, and the extrusion temperature is controlled at 110℃-130℃. The outer sheath 9 is tightly fitted to the armor layer 8 and has excellent temperature resistance, aging resistance, corrosion resistance, and UV resistance. The temperature resistance range is -40℃ to 80℃, forming a sealing and protective barrier. It can adapt to the complex environment of long-distance laying (direct burial, pipeline, overhead, etc.) and resist external erosion such as soil compression, rainwater soaking, atmospheric condensation, and ultraviolet radiation. It provides external protection for the double all-dry water-blocking system, ensuring long-term stable water-blocking performance.

[0058] This application relies on the core design of "double dry water barrier," combined with differentiated insulation, unequal pitch stranding, and multi-layer structure protection, to specifically address the technical defects of existing grease-filled cables. It achieves the core objectives of "dry-type long-lasting water barrier, environmentally friendly and convenient, structurally stable, and reliable transmission." The specific working principle is as follows: (1) Core All-Dry Water-Blocking Principle: Completely abandoning the traditional grease-filled mode, a three-level all-dry water-blocking system is constructed, consisting of "line-to-line micro-water-blocking + first water-blocking layer + second water-blocking layer". The outer and inner sheaths first physically isolate and block most of the external water vapor; after a small amount of water vapor breaks through the sheath, the water-blocking tape and water-blocking yarn of the second water-blocking layer expand rapidly upon contact with water (expansion ratio ≥300%, expansion time ≤5min), instantly blocking the water vapor penetration channel; if a trace amount of water continues to penetrate inward, the double-layer water-blocking tape, polyethylene protective layer, and single-layer water-blocking tape of the first water-blocking layer will form a new water-blocking defense line, completely preventing water vapor from contacting the cable core. All water-blocking materials are environmentally friendly and biodegradable, with no petroleum-based components, in line with the trend of green communication development.

[0059] The construction of the line-pair level micro water-blocking barrier is particularly crucial. Glass fiber-based environmentally friendly expandable water-blocking yarn is wrapped around each signal pair and each low-frequency four-wire group to form a line-pair level micro water-blocking barrier. Through the coupling design of unequal pitch twisting and water-blocking yarn wrapping, the water-blocking yarn is self-locked and anchored to the surface of the twisted line pairs, forming a structurally stable and uniformly distributed initial water-blocking layer. This design solves the long-standing problem of "easy displacement of water-blocking materials" in all-dry technology, laying the structural foundation for the synergistic effect of the subsequent two water-blocking barriers (the first water-blocking layer and the second water-blocking layer).

[0060] (2) Structural stability and water-blocking synergy principle: Each layer is tightly bonded through extrusion, wrapping, pressing and other processes, with no obvious gaps; environmentally friendly expansion-type water-blocking filling rope, water-blocking tape and water-blocking yarn achieve full and dense filling of the gaps inside the cable, avoiding the formation of water vapor "channels"; the armor layer provides mechanical protection while pressing the second water-blocking layer, improving the sealing effect of the water-blocking layer, and achieving the synergy of "structural stability" and "water-blocking efficiency"; the weather resistance and corrosion resistance of the outer sheath protect the water-blocking system from the outside, ensuring that the water-blocking structure is not damaged in complex laying environments and the water-blocking performance is stable for a long time.

[0061] Based on this, the armor layer generates continuous radial binding stress through a reverse gap wrapping process, which actively compresses and shapes the second water-blocking layer for a long time. This design brings the following three synergistic effects: Physical compression effect: Eliminates micron-level interfacial gaps between the second water-blocking layer and the inner sheath and armor layer, preventing moisture seepage along the interface. Directional expansion effect: Guides the water-blocking material to expand towards the cable core when it encounters water, improving sealing efficiency. Structural protection effect: Shares external mechanical stress, preventing structural damage to the water-blocking layer due to uneven stress.

[0062] This collaborative design of "armored sealing" provides mechanical protection while compressing the second water-blocking layer, enhancing the sealing effect of the water-blocking layer, achieving synergy between mechanical protection and water-blocking enhancement, and realizing a deep integration of mechanical protection and water-blocking enhancement. The weather resistance and corrosion resistance of the outer sheath further protect the water-blocking system from the outside, ensuring that the water-blocking structure is not damaged in complex laying environments and that the water-blocking performance remains stable for a long time.

[0063] Low-loss transmission and water-blocking adaptation principle: The conductor uses high-purity TR-type soft round copper wire to reduce transmission loss; the differentiated insulation design adapts to the needs of low-frequency and conventional signal transmission, reducing signal attenuation; the unequal pitch stranding design cancels the capacitance imbalance between wire pairs, reducing crosstalk interference; the dense design of the all-dry water-blocking structure avoids the problems of unstable cable core structure and electrical parameter drift caused by uneven grease filling, ensuring stable electrical performance of the cable, realizing long-distance low-loss and low-interference signal transmission, and the water-blocking structure and transmission structure do not interfere with each other, synergistically improving the overall performance of the cable.

[0064] The specific production, laying, and use of the symmetrical communication cable in this application are as follows: (1) Production process: First, TR type soft round copper wire is used to make low-frequency four-wire group conductors with a diameter of 0.903-0.905mm and signal twisted pair group conductors with a diameter of 0.704-0.705mm respectively; then, according to the differentiated insulation design, the insulation layer is extruded and wrapped with the corresponding process, and the corresponding extrusion temperature is controlled to form two types of insulated single wires; then, according to the unequal pitch requirements, multiple signal twisted pairs and multiple low-frequency four-wire groups are twisted together to form multiple groups of signal twisted pairs and multiple groups of low-frequency four-wire groups, and environmentally friendly expansion-type water-blocking yarn is wrapped around them; then, multiple groups of signal twisted pairs and multiple groups of low-frequency four-wire groups are cabled clockwise and filled with expansion-type water-blocking filling rope, and then wrapped with double-layer water-blocking tape, extruded polyethylene protective layer, and then wrapped with another layer of water-blocking tape to complete the preparation of the first water-blocking barrier; then, the shielding layer, extruded inner sheath, and second water-blocking layer (water-blocking tape + Water-blocking yarn is used to form a second water-blocking barrier. This is followed by a wrapping armor layer, further wrapping the water-blocking yarn, and finally, an extruded outer sheath. Strict control of all process parameters (extrusion temperature, wrapping density, winding overlap, etc.) ensures that each layer is tightly bonded, without damage or seams, completing cable production. The production process requires no grease filling, significantly simplifying the process, eliminating grease pollution, and significantly improving production efficiency. Furthermore, all materials meet environmental protection requirements.

[0065] (2) Laying process: Various laying methods such as direct burial, pipeline, and overhead can be adopted; Since the cable is a dry structure, there is no grease overflow during the laying process, which will not cause pollution to the construction environment. At the same time, there is no need to prepare grease cleaning tools and procedures in advance, simplifying the construction process; The cable structure is reasonably designed, and the weight and outer diameter are appropriately controlled, which facilitates transportation and laying; The armor layer can effectively protect the cable and avoid damage to the inner and outer water barrier and internal structure by external forces during the laying process, preventing the failure of water blocking performance; When splicing, the cable can be directly cut and each layer of structure can be peeled off without cleaning residual grease, which greatly improves the splicing efficiency and avoids the problem of low insulation caused by incomplete grease cleaning, ensuring the quality of splicing. After splicing, the good dry water blocking performance can still be maintained.

[0066] (3) Usage process: After the cable is laid, it is connected to the long-distance communication system. The two types of conductors transmit low-frequency signals and conventional signals respectively. Differentiated insulation and unequal pitch stranding work together to ensure low signal attenuation and no distortion. During use, if the groundwater level is high, rainwater soaking, or drastic temperature and humidity changes occur, the three-level dry water-blocking system plays a synergistic role. Through physical isolation and water expansion sealing, it effectively blocks all water vapor penetration, ensuring that the cable core is dry for a long time. This avoids signal attenuation and insulation failure caused by water entering the cable core from the root. The inner sheath, armor layer and outer sheath form a multi-layer structure to resist external environmental erosion and external impact, prevent water-blocking layer damage, and ensure long-term stability of the dry water-blocking performance. After the cable is discarded, all dry water-blocking materials and sheath materials can be recycled and degraded without environmental pollution, which is in line with the green communication development trend.

[0067] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fully dry, water-resistant, highly shielded long-distance symmetrical communication cable, characterized in that: The cable includes, from the inside out, a stranded cable core, a first water-blocking layer, a shielding layer, an inner sheath, a second water-blocking layer, an armor layer, and an outer sheath. The stranded cable core is formed by twisting multiple signal twisted pairs and multiple low-frequency four-wire groups together with environmentally friendly expanding water-blocking filler rope. Each signal twisted pair and each low-frequency four-wire group is formed by twisting multiple insulated single wires together, and after twisting, they are wrapped with environmentally friendly expanding water-blocking yarn. The twisting pitch of each signal twisted pair and each low-frequency four-wire group is different.

2. The all-dry, water-resistant, high-shield, long-distance symmetrical communication cable according to claim 1, characterized in that, The twist pitch of the signal twisted pair is set to 70mm-110mm, the twist pitch of the low-frequency four-wire group is set to 100mm-260mm, and the twist pitch difference between adjacent signal twisted pairs, adjacent low-frequency four-wire groups, and between signal twisted pairs and low-frequency four-wire groups is P, satisfying 20mm≤P≤25mm.

3. The all-dry, water-resistant, high-shielded long-distance symmetrical communication cable according to claim 1, characterized in that, The first water-blocking layer comprises, from the inside out, a double-layer environmentally friendly expandable water-blocking tape, a polyethylene protective layer, and a single-layer environmentally friendly expandable water-blocking tape; the double-layer environmentally friendly expandable water-blocking tape is wrapped around the outside of the stranded cable core, the polyethylene protective layer is extruded around the outside of the double-layer environmentally friendly expandable water-blocking tape and has a thickness of 0.5mm-0.6mm, and the single-layer environmentally friendly expandable water-blocking tape is wrapped around the outside of the polyethylene protective layer, and the overlap rate of the wrapping is ≥50%.

4. The all-dry, water-resistant, high-shield, long-distance symmetrical communication cable according to claim 1, characterized in that, The shielding layer is made of seamlessly welded industrial pure aluminum plate with a thickness of 1.7mm-1.8mm and a purity of ≥99.7%, and is wrapped around the outside of the first water-blocking layer, with a shielding effectiveness of ≥85dB to shield external electromagnetic interference.

5. The all-dry, water-resistant, high-shield, long-distance symmetrical communication cable according to claim 1, characterized in that, The inner sheath is made of low-smoke halogen-free polyolefin material extruded and wrapped around the outside of the shielding layer, and the thickness of the inner sheath is 1.0mm-1.3mm, and the extrusion temperature is 120℃-180℃.

6. The all-dry, water-resistant, high-shield, long-distance symmetrical communication cable according to claim 1, characterized in that, The second water-blocking layer includes an environmentally friendly expandable water-blocking strip and an environmentally friendly expandable water-blocking yarn arranged sequentially from the inside to the outside; the environmentally friendly expandable water-blocking strip is tightly wrapped around the outside of the inner sheath, and the environmentally friendly expandable water-blocking yarn is evenly distributed between the environmentally friendly expandable water-blocking strip and the armor layer, filling the gap between the two to ensure that there are no gaps or voids.

7. The all-dry, water-resistant, high-shield, long-distance symmetrical communication cable according to claim 1, characterized in that, The armor layer is made of double-layer high-permeability steel strip with gap wrapping. The steel strip thickness is 0.50mm-0.52mm. It is wrapped around the outside of the second water-blocking layer through a reverse gap wrapping process. The wrapping gap is less than 30%, and the wrapping angle is controlled within the range of α±5°. This makes the armor layer generate a continuous radial binding stress of 0.5MPa-1.2MPa on the inner second water-blocking layer.

8. The all-dry, water-resistant, high-shielded long-distance symmetrical communication cable according to claim 7, characterized in that, The outer side of the armor layer is filled with environmentally friendly, expandable, water-resistant yarn to ensure that there are no gaps or voids.

9. The all-dry, water-resistant, high-shield, long-distance symmetrical communication cable according to claim 1, characterized in that, The outer sheath is made of weather-resistant, low-smoke, halogen-free polyolefin material, which is extruded and wrapped around the outside of the armor layer. The thickness of the outer sheath is 2.0mm-2.2mm, and the extrusion temperature is controlled at 110℃-130℃.

10. The all-dry, water-resistant, high-shielded long-distance symmetrical communication cable according to claim 1, characterized in that, The insulated single wires in the signal twisted pair and the low-frequency four-wire group each include a conductor and an outer insulating layer. The conductor diameter of the insulated single wire in the signal twisted pair is set to 0.704mm-0.705mm, and its insulation layer is made of solid polyethylene, with a low-density polyethylene inner layer and a high-density polyethylene outer layer. The conductor diameter of the insulated single wire in the low-frequency four-wire group is set to 0.903mm-0.905mm, and its insulation layer is made of physically foamed polyolefin, with a low-density polyethylene inner layer, a high-density polyethylene outer layer, and a high-density foamed polyolefin foam layer.

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