Hollow-core hybrid optical fiber cable with gradient heat insulation barrier
By introducing a gradient design of cable core unit, expansion insulation layer and ceramic outer sheath into the optical cable, the problem that existing fire-resistant optical cables cannot dynamically build a heat insulation barrier under extreme high temperature is solved, and stable signal transmission and communication guarantee of optical fiber in high temperature environment are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-13
- Publication Date
- 2026-04-21
AI Technical Summary
Existing fire-resistant optical cables rely on static insulation layers under extreme high-temperature fires, which cannot dynamically construct an efficient thermal barrier, resulting in excessively rapid temperature rise of the optical fiber and easy communication interruption.
The hollow hybrid optical cable design with a gradient thermal barrier is adopted, including cable core unit, expansion thermal insulation layer and ceramic outer sheath. The flame-retardant polymer tube shell, foamed ceramic material and ceramic outer sheath form a dynamic thermal barrier at high temperature, and construct a multi-level collaborative protection mechanism.
In extreme fire environments, effectively controlling the cable core temperature within a safe threshold ensures stable signal transmission over long periods, enhancing the fire resistance and communication reliability of optical cables.
Smart Images
Figure CN224152715U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of optical fiber and cable technology, specifically to a hollow hybrid optical fiber and cable with a gradient thermal insulation barrier. Background Technology
[0002] With the widespread adoption of fiber-to-the-home (FTTH) and the large-scale construction of new information infrastructure such as 5G and data centers, the deployment environment for communication optical cables is becoming increasingly complex and demanding. Optical cables are no longer simply laid in dedicated communication conduits, but are increasingly traversing building electrical shafts, vertical shafts, and integrated utility tunnels, and are being laid in the same trench or close to power cables. While this wiring method saves space, it also brings significant safety hazards: if a fire breaks out in an adjacent power line due to overload, short circuit, or other reasons, the resulting high-temperature flames and thermal shock will directly affect the optical cable, posing a serious threat to its physical integrity and signal transmission stability.
[0003] In critical scenarios with extremely high business continuity requirements, such as data centers, rail transit, financial centers, and high-rise buildings, communication interruptions can lead to huge economic losses or safety accidents. Therefore, the market has raised the requirements for the fire safety performance of optical cables to far exceed the conventional flame retardant rating. This means that optical cables are not only required to be flame retardant, but also to be able to continuously ensure optical signal transmission in flames for a period of time after a fire breaks out, thus buying valuable time for emergency communications, personnel evacuation, and fire rescue.
[0004] Currently, the mainstream technical approach in the industry to improve the fire resistance of optical cables mainly relies on adding a heat insulation barrier layer outside the cable core. Commonly used materials include:
[0005] Wrapped mica tape: Mica is structurally stable and non-flammable at high temperatures and has a certain heat insulation effect. However, it is prone to embrittlement and pulverization under continuous high-temperature flame burning, and its mechanical strength is lost quickly. Moreover, due to process limitations, it is difficult to achieve a complete seal, and heat may penetrate through the gaps.
[0006] Ceramicized silicone rubber sheath: This material has the elasticity of rubber at room temperature and can be sintered to form a ceramic hard shell at high temperatures. However, its ceramicization process depends on the complete combustion and decomposition of the polymer matrix. There is a period of weak strength before the formation of a dense ceramic body, and the thermal insulation efficiency of a single ceramic layer is limited. Under the action of extreme high temperature for a long time, heat will still be gradually conducted to the cable core.
[0007] Metal sheath: The optical fiber is protected by metal tubes such as stainless steel. Although it can resist high temperature, it has problems such as heavy weight, high cost, poor bending performance and susceptibility to electromagnetic interference, which limits its application range.
[0008] In summary, existing fire-resistant solutions are essentially "passive defenses," and their insulation performance relies on the inherent static thermal resistance of the materials. In a fierce fire, these static insulation layers may fail due to rapid ablation, structural damage, or thermal saturation, causing the cable core temperature to rise to the fiber's failure threshold in a short period of time, resulting in transmission interruption.
[0009] Therefore, the field of communication infrastructure security faces a technical challenge: how to design an optical cable that can dynamically and proactively build and maintain an efficient heat insulation barrier in extreme high-temperature fire environments, thereby keeping the operating temperature of the internal optical fibers below a safe threshold for a long time and ensuring the survival capability of the communication link in a fire. Utility Model Content
[0010] The purpose of this invention is to provide a hollow hybrid optical fiber cable with a gradient thermal barrier, which solves the technical problem that existing fire-resistant optical cables rely on static thermal insulation layers under extreme high temperatures and cannot dynamically construct an efficient thermal barrier, resulting in excessively rapid temperature rise of internal optical fibers and easy communication interruption.
[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0012] A hollow hybrid optical fiber cable with a gradient thermal insulation barrier includes a cable core unit, an expansion thermal insulation layer, and a ceramicized outer sheath arranged from the inside to the outside.
[0013] The cable core unit contains at least one hollow optical fiber;
[0014] The expansion insulation layer is composed of multiple micro expansion insulation tubes; each micro expansion insulation tube includes a flame-retardant polymer shell and a foamed ceramic material filled inside it.
[0015] The ceramicized outer protective layer covers the outside of the expansion insulation layer and is composed of a composite material that can be transformed into a ceramic body at high temperatures above 600 degrees Celsius.
[0016] A further technical solution is that the cable core unit also includes G.654.E(B1.2e) optical fiber and G.652.D(B1.3) optical fiber mixed with the hollow optical fiber.
[0017] A further technical solution is that the optical fiber in the cable core unit is placed inside a flame-retardant PBT sleeve; the flame-retardant PBT sleeve is filled with flame-retardant fiber paste.
[0018] A further technical solution is that the flame-retardant polymer tube shell is a flame-retardant polyolefin tube with an outer diameter of 0.8-1.0 mm and a wall thickness of 0.08-0.12 mm.
[0019] A further technical solution is that the foamed ceramic material expands by a factor of not less than five when heated, and can be sintered at high temperature to form a porous ceramic heat insulation body.
[0020] A further technical solution is that multiple micro-expansion insulation tubes in the expansion insulation layer are evenly distributed circumferentially along the cable core unit in a single layer or multiple layers, and extend axially along the cable core unit.
[0021] A further technical solution is that the micro-expansion heat insulation tube is embedded in the ceramicized outer protective layer, forming an integrated composite structure with the ceramicized outer protective layer.
[0022] A further technical solution is that the optical cable also includes a flame-retardant pad layer located between the cable core unit and the expansion insulation layer.
[0023] A further technical solution is that the cable core unit has a non-metallic reinforcing member at its center, the non-metallic reinforcing member including glass fiber reinforced plastic located at the center and filler rope located around the glass fiber reinforced plastic.
[0024] Compared with the prior art, the beneficial effects of this utility model are:
[0025] The optical cable provided by this invention achieves a breakthrough improvement in fire resistance through a multi-level synergistic protection mechanism that combines flame-retardant protection, active expansion insulation, and ceramicized ablation resistance. The inner hollow-core optical fiber and flame-retardant structure ensure high-temperature signal stability and early protection; the core embedded expansion insulation tube actively expands and ceramicizes during a fire, dynamically constructing a highly efficient heat insulation barrier; the outer ceramicized sheath provides structural support and direct resistance to flames. The combination of these three elements enables the optical cable to maintain its core temperature within a safe threshold for extended periods even in extreme fire environments, ensuring stable signal transmission over long periods and providing reliable protection for fire-safe communication in critical facilities such as data centers and rail transit. Attached Figure Description
[0026] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the following drawings are provided for illustration:
[0027] Figure 1 This is a schematic diagram of the structure of this utility model.
[0028] Icons: Cable core unit 1, hollow fiber 11, G.654.E (B1.2e) fiber 12, G.652.D (B1.3) fiber 13, expansion insulation layer 2, flame-retardant polymer tube shell 21, foamed ceramic material 22, ceramicized outer sheath 3, flame-retardant PBT sleeve 4, flame-retardant fiber paste 41, flame-retardant pad 5, glass fiber reinforced plastic 6, filler rope 7. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.
[0030] Example:
[0031] like Figure 1 As shown, this utility model provides a hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier, including a cable core unit 1, an expansion thermal insulation layer 2, and a ceramicized outer sheath 3 arranged from the inside out; the cable core unit 1 includes at least one hollow optical fiber 11 (four in this embodiment); specifically, the hollow optical fiber 11 uses anti-resonant hollow optical fiber 11 (HC-ARF) as the transmission medium, and its optical signal transmission characteristics in the air give it an inherently extremely low temperature drift coefficient and radiation resistance, fundamentally improving the signal stability and survivability of the G.654.E (B1.2e) optical fiber 12 in high-temperature environments; the expansion thermal insulation layer 2 is composed of multiple micro-expansion thermal insulation tubes, each micro-expansion thermal insulation tube including a flame-retardant polymer tube shell 21 and a foamed ceramic material 22 filled inside it; specifically, the foamed ceramic material 22 includes a paste or powder material composed of inorganic silicate, ceramic precursor and foaming agent; the ceramicized outer sheath 3 covers the outside of the expansion thermal insulation layer 2 and is composed of a composite material that can be transformed into a ceramic body at high temperatures.
[0032] The principles and beneficial effects of the above technical solution:
[0033] This solution constructs a triple-gradient protection system consisting of the cable core, an expansion insulation layer 2, and a ceramicized outer sheath 3. In a high-temperature fire environment, the outer ceramicized sheath first forms a dense ceramic shell to resist direct flame impact. The foamed ceramic material 22 in the adjacent expansion insulation layer 2 rapidly expands and ceramicizes upon heating, forming a significantly thicker, highly efficient heat insulation barrier filled with closed pores outside the cable core unit 1. The inner hollow optical fiber 11, because light travels through air, is minimally affected by temperature. This achieves gradient protection from "ablation resistance" to "heat insulation" to "signal stability." It systematically solves the problem of rapid heat intrusion causing G.654.E (B1.2e) optical fiber 12 failure under extreme high temperatures, and maintains the cable core temperature below the safe threshold for extended periods in high-temperature flames, significantly improving the fire resistance survival time and communication assurance capabilities of the optical cable.
[0034] In this embodiment, the cable core unit 1 further includes G.654.E(B1.2e) optical fiber 12 and G.652.D(B1.3) 13 mixed with the hollow optical fiber 11; specifically, the cable core unit 1 includes hollow optical fiber 11, G.654.E(B1.2e) optical fiber 12 and G.652.D(B1.3) optical fiber 13.
[0035] The principles and beneficial effects of the above technical solution:
[0036] This solution utilizes the signal stability of hollow-core fiber 11 under extreme high temperatures to ensure critical channels, while employing mature and cost-effective G.654.E (B1.2e) fiber 12 and G.652.D (B1.3) fiber 13 to handle the main transmission capacity, achieving an optimized combination of performance and cost. In this way, hollow-core fiber 11 ensures the signal baseline survivability under extreme conditions such as fires, while the combination of conventional G.654.E (B1.2e) fiber 12 meets the daily high-speed, high-capacity transmission requirements, improving the overall practicality and economy of the optical cable.
[0037] In this embodiment, the G.654.E(B1.2e) optical fiber 12 in the cable core unit 1 is placed inside the flame-retardant PBT sleeve 4, and the flame-retardant PBT sleeve is filled with flame-retardant fiber paste 41; specifically, the flame-retardant PBT sleeve is made of modified polybutylene terephthalate.
[0038] The principles and beneficial effects of the above technical solution:
[0039] Flame-retardant fiber paste 41 provides buffering, water resistance and initial flame retardancy. The outer flame-retardant PBT sheath has excellent mechanical properties at room temperature and can form a carbonized layer in the early stage of heating, which plays a role in flame retardancy and short-term protection, preventing G.654.E(B1.2e) optical fiber 12 from being damaged in the early stage of a fire.
[0040] In this embodiment, the flame-retardant polymer shell 21 of the micro expansion insulation tube is a flame-retardant polyolefin tube with an outer diameter of 0.8-1.0 mm and a wall thickness of 0.08-0.12 mm; specifically, the nominal diameter is 0.9 mm and the wall thickness is 0.1 mm.
[0041] The principles and beneficial effects of the above technical solution:
[0042] Flame-retardant polyolefin materials are used to ensure the flexibility and processability of the tube shell at room temperature, as well as its flame retardancy in the initial stage of heating. The miniaturization of the tube shell allows it to be embedded in the sheath at high density, which does not affect the bending performance of the optical cable, and provides stable encapsulation for the internal foamed ceramic material 22. This enables the stable preservation of the thermal insulation material under normal conditions and the controlled release in case of fire. The miniaturized design makes the thermal insulation response faster and the distribution more uniform, laying the foundation for building an efficient distributed thermal insulation barrier.
[0043] In this embodiment, after the foamed ceramic material 22 is heated and expands, its volume expansion factor is greater than or equal to five times (seven times in this embodiment), and it can be sintered at high temperature to form a porous ceramic heat insulation body.
[0044] The principles and beneficial effects of the above technical solution:
[0045] The foamed ceramic material 22 contains a foaming agent and a ceramic precursor. When exposed to high temperatures, the foaming agent generates a large amount of gas, causing it to expand dramatically and double in volume, thus filling the gaps and thickening the insulation layer. At the same time, the ceramic precursor is sintered at high temperatures, solidifying the expanded porous structure into a foamed ceramic body with mechanical strength. By combining physical expansion and thickening with chemical ceramic solidification, a lightweight, high-porosity, and extremely thermally stable rigid insulation layer is dynamically constructed, whose insulation performance far exceeds that of static insulation materials.
[0046] In this embodiment, multiple micro-expansion insulation tubes in the expansion insulation layer 2 are evenly distributed along the circumference of the cable core unit 1 in a single layer or multiple layers (two layers in this embodiment) and extend along the axial direction of the cable core unit 1.
[0047] The principles and beneficial effects of the above technical solution:
[0048] By arranging micro-expansion insulation tubes evenly in the circumference and continuously in the longitudinal direction, it is ensured that the cable core is surrounded by one or more layers of tightly arranged insulation units at any cross-section of the optical cable. This arrayed, full-coverage layout allows the insulation units in front to respond synchronously and quickly form a continuous insulation ring whenever heat invades from any direction during a fire. This achieves a seamless and highly reliable insulation response, avoids "thermal bridges" caused by localized insulation deficiencies, ensures that heat is uniformly blocked and dissipated, and greatly improves the integrity and effectiveness of the overall insulation barrier.
[0049] In this embodiment, the micro-expansion heat insulation tube is embedded in the ceramic outer protective layer 3 through a co-extrusion process, forming an integrated composite structure with the ceramic outer protective layer 3.
[0050] The principles and beneficial effects of the above technical solution:
[0051] By using a customized co-extrusion die, the pre-arranged micro-expansion insulation tubes are simultaneously wrapped and fixed within the ceramicized sheath material during melt extrusion molding, forming an integrated composite sheath after cooling. This process not only achieves high-efficiency production, but more importantly, the ceramicized sheath material forms a tight "constraint" on the internal insulation tubes after curing. The integrated structure ensures the structural stability and consistency of the product; the "constrained expansion" mechanism forces the foamed ceramic material 22 to expand orderly within the confined space, ultimately forming a closed-cell ceramic honeycomb structure with higher strength and more uniform pores, whose thermal insulation and mechanical properties are far superior to those of the free expansion state.
[0052] In this embodiment, the optical cable also includes a flame-retardant pad 5 located between the cable core unit 1 and the expansion insulation layer 2; the flame-retardant pad 5 is a mica tape.
[0053] The principles and beneficial effects of the above technical solution:
[0054] The flame-retardant pad 5 wraps around the cable core unit 1, serving as a physical spacer between the cable core and the outer composite sheath. It provides additional heat insulation and flame-retardant cushioning in the early stages of a fire and protects the cable core from the high temperatures of extrusion during manufacturing. It provides another layer of passive protection for the cable core; simultaneously, as a structural transition layer, it helps maintain the roundness of the cable core and ensures the uniformity of the outer composite sheath thickness, thereby guaranteeing stable final thermal insulation performance.
[0055] In this embodiment, a non-metallic reinforcing member is provided at the center of the cable core unit 1; the non-metallic reinforcing member includes glass fiber reinforced plastic 6 and filler rope 7.
[0056] The principles and beneficial effects of the above technical solution:
[0057] A glass fiber reinforced plastic (6) and filler rope (7) are installed at the center of the cable core, serving as the "skeleton" of the entire optical cable. It primarily bears the tensile forces during laying and operation, preventing tension on the hollow-core optical fibers (11), G.654.E (B1.2e) optical fibers (12), and G.652.D (B1.3) optical fibers (13), while also providing lateral pressure resistance to maintain the stability of the cable core structure. The use of non-metallic materials avoids induced currents and is suitable for complex electromagnetic environments. This ensures the optical cable possesses the necessary mechanical strength to meet the requirements of laying and long-term use; a stable cable core structure is a crucial prerequisite for the uniform and reliable formation and function of the outer gradient thermal insulation barrier.
[0058] Although the present invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter combination within the scope of the disclosure, drawings, and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.
Claims
1. A hollow-core hybrid fiber-optic cable having a gradient thermal shield, characterized by, This includes the cable core unit, the expansion insulation layer, and the ceramicized outer sheath, arranged from the inside out. The cable core unit contains at least one hollow optical fiber; The expansion insulation layer is composed of multiple micro expansion insulation tubes; each micro expansion insulation tube includes a flame-retardant polymer shell and a foamed ceramic material filled inside it. The ceramicized outer protective layer covers the outside of the expansion insulation layer and is composed of a composite material that can be transformed into a ceramic body at high temperatures above 600 degrees Celsius.
2. The hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1, characterized in that: The cable core unit also includes G.654.E(B1.2e) optical fiber and G.652.D(B1.3) optical fiber mixed with the hollow optical fiber.
3. The hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1, characterized in that: The optical fiber in the cable core unit is placed inside a flame-retardant PBT sleeve; the flame-retardant PBT sleeve is filled with flame-retardant fiber paste.
4. A hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1, characterized in that: The flame-retardant polymer tube shell is a flame-retardant polyolefin tube with an outer diameter of 0.8-1.0 mm and a wall thickness of 0.08-0.12 mm.
5. A hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1 or 4, characterized in that: The foamed ceramic material expands by a factor of not less than five when heated, and can be sintered to form a porous ceramic insulation.
6. A hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1, characterized in that: The multiple micro-expansion insulation tubes in the expansion insulation layer are evenly distributed circumferentially along the cable core unit in a single layer or multiple layers, and extend axially along the cable core unit.
7. A hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1, characterized in that: The micro-expansion heat insulation tube is embedded in the ceramicized outer protective layer, forming an integrated composite structure with the ceramicized outer protective layer.
8. A hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1, characterized in that: The optical cable also includes a flame-retardant pad layer located between the cable core unit and the expansion insulation layer.
9. A hollow-core hybrid optical fiber cable with a gradient thermal insulation barrier according to claim 1, characterized in that: The cable core unit has a non-metallic reinforcing member at its center; the non-metallic reinforcing member includes glass fiber reinforced plastic located at the center and filler rope located around the glass fiber reinforced plastic.