Central-tube air-blown micro optical cable

Abstract

The present application relates to a central-tube air-blown micro optical cable. A co-extruded sleeve comprises a polycarbonate layer and an outer polybutylene terephthalate layer; and the ratio of the annular area corresponding to the cross section of the polycarbonate layer to the annular area corresponding to the cross section of the polybutylene terephthalate layer is 1.69-4.3. The above structure utilizes the characteristics of amorphism and relatively high hardness of polycarbonate and the characteristic of the density thereof being less than that of polybutylene terephthalate; and by changing the sizes and the ratio of the annular areas of the polycarbonate layer and the polybutylene terephthalate layer, the weight ratio of the polycarbonate layer to the polybutylene terephthalate layer is adjusted, and the proportion of the polycarbonate layer is increased, thereby improving the rigidity of the optical cable while reducing the weight thereof. In addition, the polycarbonate layer has a low shrinkage rate, which further makes the size of the optical cable smaller than that of a conventional sleeve structure, thereby finally achieving the purposes of weight reduction, rigidity improvement and size reduction, increasing the air-blowing distance, and improving the air-blowing performance of the optical cable.

Description

A miniature optical cable for central tube air blowing Technical Field

[0001] This application relates to the field of optical fiber communication technology, and in particular to a miniature optical cable for central tube air blowing. Background Technology

[0002] With the development of optical network services, the shortage of communication pipeline resources is inevitable. Expanding pipeline capacity using traditional methods requires high road excavation and compensation costs, while micro-pipe and micro-cable technology can expand the capacity of existing pipelines, maximizing the utilization of existing facilities.

[0003] To make full use of pipeline resources, miniaturization of optical cables and high fiber density have become the core demands of customers; however, a small outer diameter of optical cables often results in insufficient overall rigidity. If the optical cable is too soft, it will greatly affect the air blowing performance of the optical cable, and the air blowing distance and efficiency will not meet the application scenarios.

[0004] Summary of the Invention

[0005] This application provides a miniature optical cable for air blowing in a central tube, which solves the problem in related technologies where the miniaturization of optical cables to make full use of pipeline resources results in insufficient overall rigidity of the optical cable, affecting the air blowing performance of the optical cable.

[0006] In a first aspect, a micro optical cable for air blowing with a central tube is provided, which includes an optical fiber, and a co-extruded tube and a sheath are sequentially provided outside the optical fiber. The co-extruded tube includes a polycarbonate layer and a polybutylene terephthalate layer located outside the polycarbonate layer.

[0007] The ratio of the annular area corresponding to the cross-section of the polycarbonate layer to the annular area corresponding to the cross-section of the polybutylene terephthalate layer is 1.69 to 4.3.

[0008] In some embodiments, the area ratio is 1.69 to 3.38; or,

[0009] The area ratio is 3.38 to 4.3.

[0010] In some embodiments, the area ratio is 1.69, 3.38, or 4.3.

[0011] In a second aspect, a micro optical cable for air blowing with a central tube is provided, which includes an optical fiber, and a co-extruded sleeve and a sheath are sequentially provided outside the optical fiber. The co-extruded sleeve includes a polycarbonate layer and a polybutylene terephthalate layer located outside the polycarbonate layer.

[0012] The weight ratio of the polycarbonate layer to the polybutylene terephthalate layer is 1.56-3.96.

[0013] In some embodiments, the weight ratio is 1.56 to 3.11; or,

[0014] The weight ratio is 3.11 to 3.96.

[0015] In some embodiments, the weight ratio is 1.56, 3.11, or 3.96.

[0016] In some embodiments, the polycarbonate layer is filled with fiber paste inside and outside the optical fiber; the sheath is made of polyethylene or low-smoke halogen-free material; and aramid yarn is provided between the co-extruded tube and the sheath.

[0017] In some embodiments, the outer diameter of the sheath is 2.1-3.8 mm, and the wall thickness is 0.3-0.5 mm;

[0018] The optical fiber has 1-36 cores; the optical fiber diameter is 200μm or 250μm.

[0019] In some embodiments, the air blowing distance of the central tube air blowing miniature optical cable under air blowing pressure is greater than 1250m; the air blowing distance is measured in an environment with a temperature range of 5℃-38℃, a humidity range of 30%-65%, and a 7 / 4mm air blowing pipe.

[0020] In some embodiments, the lateral pressure resistance of the micro-optical cable used for air blowing in the central tube is greater than 1000N. The lateral pressure resistance is measured under the conditions of an air blowing distance in an environment with a temperature range of 5°C-38°C and a humidity range of 30%-65%, using a 7 / 4mm air blowing pipe.

[0021] The beneficial effects of the technical solution provided in this application include:

[0022] This application provides a micro optical cable for air blowing with a central tube. The co-extruded tube includes a polycarbonate layer and an outer polybutylene terephthalate (PBPT) layer. The ratio of the annular area corresponding to the cross-section of the polycarbonate layer to the annular area corresponding to the cross-section of the PBPT layer is 1.69–4.3. This structure utilizes the non-crystalline nature and high hardness of polycarbonate, as well as its lower density than PBPT. By changing the size ratio and annular area ratio of the polycarbonate and PBPT layers, the weight ratio between the two layers is adjusted, increasing the proportion of the polycarbonate layer. This reduces the weight of the optical cable while improving its rigidity. Furthermore, the polycarbonate layer has a low shrinkage rate, which further reduces the size of the optical cable compared to conventional tube structures. Ultimately, this achieves the goals of weight reduction, increased rigidity, and smaller size, while increasing the air blowing distance and improving the air blowing performance of the optical cable. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 is a cross-sectional schematic diagram of the micro optical cable for air blowing in the center tube provided in the embodiment of this application;

[0025] Figure 2 is a view showing the inner and outer diameter dimensions of the polycarbonate layer and the outer polybutylene terephthalate layer provided in the embodiments of this application.

[0026] In the diagram: 1. Optical fiber; 2. Sheath; 3. Polycarbonate layer; 4. Polybutylene terephthalate layer; 5. Fiber paste; 6. Aramid yarn. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] To fully utilize pipeline resources, miniaturization and high fiber density of optical cables have become core customer demands. Small outer diameters often result in insufficient overall rigidity, and excessive flexibility significantly impacts air-blowing performance, making the air-blowing distance and efficiency unsuitable for application scenarios. The core technical challenge of miniaturized air-blowing optical cables lies in achieving both small outer diameter and light weight while maintaining sufficient rigidity to ensure good air-blowing performance.

[0029] In a central tube air-blown optical cable installation, the cable is suspended within the duct by airflow during air-blowing construction. The thrust of the airflow and the air-blowing equipment propels the cable forward within the air-blowing microtube. Only with sufficient rigidity can the cable avoid severe deformation during operation within the duct.

[0030] The core technical challenge of miniature air-blown optical cables is to ensure sufficient rigidity to guarantee good air-blowing performance while meeting the requirements of small outer diameter and light weight.

[0031] The common approach to increasing the rigidity of optical cables is to incorporate rigid reinforcements, such as GFRP (glass fiber reinforced plastic) rods. However, this design inevitably increases the cable size, pushing the cable size beyond its limits. On the other hand, smaller cable sizes result in relatively lower rigidity. Insufficient rigidity leads to a significant reduction in air blowing distance, potentially making normal construction impossible.

[0032] To address the above problems, this application provides a miniature optical cable for air blowing in a central tube, which solves the problem in related technologies where the miniaturization of the optical cable, in order to make full use of pipeline resources, results in insufficient overall rigidity of the optical cable, affecting the air blowing performance of the optical cable.

[0033] Please refer to Figures 1 and 2. A micro optical cable for air blowing with a central tube includes an optical fiber 1, and a co-extruded tube and a sheath 2 are sequentially provided outside the optical fiber 1. The co-extruded tube includes a polycarbonate layer 3 and a polybutylene terephthalate layer 4 located outside the polycarbonate layer 3.

[0034] The ratio of the annular area corresponding to the cross-section of polycarbonate layer 3 to the annular area corresponding to the cross-section of polybutylene terephthalate layer 4 is 1.69 to 4.3. The above cross-sections are perpendicular to the axial direction of the optical cable length, and the two annulus rings are located on the same cross-section, as shown in Figure 2.

[0035] The above structure utilizes the non-crystalline nature and high hardness of polycarbonate (PC), as well as its lower density than polybutylene terephthalate (PBT). By changing the size ratio and annular area ratio of the polycarbonate and PBT layers, the weight ratio between them is adjusted. In other words, the proportion of the polycarbonate layer is increased, thereby reducing the weight of the optical cable while improving its rigidity. In addition, the low shrinkage rate of the polycarbonate layer further allows the optical cable to be smaller than that of conventional sheath structures, ultimately achieving the goals of weight reduction, increased rigidity, and smaller size, while increasing the air blowing distance and improving the air blowing performance of the optical cable.

[0036] The co-extruded tube and optical fiber 1 form an optical unit. The optical cable of this application improves the overall rigidity of the optical cable by increasing the rigidity of the optical unit itself.

[0037] By controlling the ratio of the annular area of ​​the polycarbonate layer and the polybutylene terephthalate layer, and thus the weight ratio between the polycarbonate layer and the polybutylene terephthalate layer, the rigidity of the optical cable can be adjusted, the weight reduced, and the overall size of the optical cable decreased, thereby increasing the air-blowing distance of the optical cable.

[0038] Of course, in order to better and more comprehensively define the optical cable resulting from the above structure, further limitations are made. Characterized by the final product parameters, a micro optical cable for air blowing with a central tube is proposed, which includes an optical fiber 1, and a co-extruded tube and a sheath 2 are sequentially provided outside the optical fiber 1. The co-extruded tube includes a polycarbonate layer 3, and a polybutylene terephthalate layer 4 located outside the polycarbonate layer 3;

[0039] The weight ratio of polycarbonate layer 3 to polybutylene terephthalate layer 4 is 1.56-3.96.

[0040] In some preferred embodiments, the weight ratio is 1.56 to 3.11; or,

[0041] The area ratio is 3.11 to 3.96.

[0042] In some preferred embodiments, the weight ratio is 1.56, 3.11, or 3.96.

[0043] Based on the above explanation, when determining whether a structure belongs to the above structures, we can distinguish them by the final weight ratio. There is no need to measure the dimensions for calculation; we can directly measure the weight. In other words, as long as the weight ratio of the polycarbonate layer 3 and the polybutylene terephthalate layer 4 of the micro optical cable for air blowing in the central tube is within the above range, it is a structure covered by this application.

[0044] The underlying principle of controlling the ratio of the annular area to the weight ratio will be explained in detail below:

[0045] Therefore, this application specifies the specific dimensions of the polycarbonate layer 3 and the polybutylene terephthalate layer 4 of the co-extruded sleeve of the optical cable.

[0046] The principle by which the weight ratio can be adjusted by changing the size in this application will be explained in detail below:

[0047] Refer to Figure 2 and the following calculation formula:

[0048] M PC Weight of polycarbonate (PC) layer;

[0049] M PBT Weight of the polybutylene terephthalate layer;

[0050] ρ1: Density of polybutylene terephthalate; the density of polybutylene terephthalate is 1.31~1.55 g / cm3; in this application, 1.3 g / cm3 is used.

[0051] ρ2: Polycarbonate density; the density of polycarbonate is generally between 1.20 and 1.22 g / cm³. 3This application uses 1.2 g / cm 3 .

[0052] D1: Outer diameter of the polybutylene terephthalate layer;

[0053] D2: Inner diameter of polybutylene terephthalate layer. Due to the co-extrusion process, the inner diameter of polybutylene terephthalate layer is also the outer diameter of polycarbonate layer.

[0054] D3: Inner diameter of the PC layer; π is the mathematical constant pi. See Figure 2 for the inner and outer diameters marked above.

[0055] As can be seen from the above formula, it is actually related to the inner and outer diameters of the polybutylene terephthalate layer and the inner and outer diameters of the polycarbonate layer; however, the specific dimensions vary depending on the requirements, and it is difficult to define the dimensions precisely, but as long as their weight ratio is within the range mentioned in this application, they are all within the scope of this solution.

[0056] The above explanation demonstrates that changing the dimensions between the polycarbonate layer and the polybutylene terephthalate layer can ultimately achieve the adjustment of the weight ratio.

[0057] Referring to the table below, the air blowing distance under different weight ratios was tested in practice. Co-extrusion sleeve production can effectively improve the air blowing performance of optical cables. As the weight ratio of PC layer and polybutylene terephthalate layer increases, the air blowing distance increases significantly.

[0058] From the table above, we can see that the weight ratio exceeding 1200m in airflow distance is 1.56 or higher. Therefore, the optimal M... PC :M PBT The ratio is 1.56-3.96. After conversion, the ratio of the annular area of ​​the polycarbonate layer to that of the polybutylene terephthalate layer is 1.69-4.3.

[0059] Therefore, the ratio of the annular area of ​​the polycarbonate layer to that of the polybutylene terephthalate layer can also be specifically required to be: a ratio of 1.69 to 3.38; or a ratio of 3.38 to 4.3.

[0060] The ratio of the annular area of ​​the polycarbonate layer to the polybutylene terephthalate layer can also be specifically required to be any one of 1.69, 3.38 or 4.3.

[0061] In some preferred embodiments, fiber grease 5 is filled within the polycarbonate layer and outside the optical fiber; the sheath 2 is made of polyethylene or low-smoke halogen-free material. The outer diameter of the sheath 2 is 2.1-3.8 mm. The optical fiber 1 has 1-36 cores; the diameter of the optical fiber 1 is 200 μm or 250 μm. Aramid yarn 6 is provided between the co-extruded tube and the sheath 2; the lateral pressure resistance of the air-blown micro-optical cable with the central tube is greater than 1000 N.

[0062] The outer polybutylene terephthalate (PET) layer and the inner fiber paste prevent the PC layer from being in long-term contact with moisture in the air, perfectly solving the problem of the PC layer being prone to hydrolysis over a long period of time. On the other hand, PC itself does not shrink and has relatively stable dimensions, which allows the optical cable to have good temperature performance even with a smaller design size.

[0063] In some preferred embodiments, the outer diameter of the optical cable ranges from 2.4 to 2.6 mm, the wall thickness ranges from 0.3 to 0.5 mm, the preferred weight ratio of polycarbonate layer to polybutylene terephthalate layer is 1.56 to 3.96, the number of optical cores includes 2 to 12, the optical fiber is 250 μm, the air blowing distance is greater than 1250 m, and the lateral pressure resistance is greater than 1000 N.

[0064] In summary, the applicant has realized that adjusting the weight ratio between the polycarbonate layer and the polybutylene terephthalate layer can achieve the above-mentioned effects. The applicant has conducted several tests and obtained the above structure:

[0065] The air blowing distance of the micro optical cable used for air blowing in the central tube is greater than 1250m under air blowing pressure; the air blowing distance is measured in an environment with a temperature range of 5℃-38℃, a humidity range of 30%-65%, and a 7 / 4mm air blowing pipe.

[0066] The lateral pressure resistance of the micro optical cable used for air blowing in the central tube is greater than 1000N. The lateral pressure resistance is measured under the conditions of an air blowing distance in an environment with a temperature range of 5℃-38℃ and a humidity range of 30%-65%, using a 7 / 4mm air blowing pipe.

[0067] The optical cable involved in this application uses a co-extruded tube and the optical fiber inside as the optical unit. At the same time, the weight ratio of PC to PBT layers in the co-extruded tube must reach a certain range to ensure that the optical cable has an air-blowing distance of more than 1200m.

[0068] In some preferred embodiments, in the actual production process, it is generally based on a determined M PC :M PBT The ratio, and the inner and outer diameters of the polybutylene terephthalate layer are used to determine the inner and outer diameters of the polycarbonate layer, thereby ultimately manufacturing a miniature optical cable for central tube air blowing that achieves the goals of weight reduction, increased rigidity, reduced size, increased air blowing distance, and improved air blowing performance of the optical cable.

[0069] After production, inspect the products to see if they meet the above weight ratio requirements. This can be done by measuring with calipers or by taking photos for image calculation.

[0070] The beneficial effects of this application are:

[0071] The above structure utilizes the non-crystalline nature and high hardness of polycarbonate (PC), as well as its lower density than polybutylene terephthalate (PBT). By changing the size ratio and annular area ratio of the polycarbonate and PBT layers, the weight ratio between them is adjusted. In other words, the proportion of the polycarbonate layer is increased, thereby reducing the weight of the optical cable while improving its rigidity. In addition, the low shrinkage rate of the polycarbonate layer further allows the optical cable to be smaller than that of conventional sheath structures, ultimately achieving the goals of weight reduction, increased rigidity, and smaller size, while increasing the air blowing distance and improving the air blowing performance of the optical cable.

[0072] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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 between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0073] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0074] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A central tube air-blowing micro cable comprising an optical fiber (1), the optical fiber (1) being surrounded by a co-extrusion jacket and a sheath (2) in sequence, characterized in that: the co-extrusion jacket comprises a polycarbonate layer (3) and a polybutylene terephthalate layer (4) outside the polycarbonate layer (3); and the area ratio of the corresponding annular area of the polycarbonate layer (3) to the corresponding annular area of the polybutylene terephthalate layer (4) is 1.69-4.

3.

2. The central tube air-blowing micro cable according to claim 1, characterized in that: the area ratio is 1.69-3.38; or the area ratio is 3.38-4.

3.

3. The central tube air-blowing micro cable according to claim 1, characterized in that: the area ratio is 1.69, 3.38 or 4.

3.

4. A central tube air-blowing micro cable comprising an optical fiber (1), the optical fiber (1) being surrounded by a co-extrusion jacket and a sheath (2) in sequence, characterized in that: the co-extrusion jacket comprises a polycarbonate layer (3) and a polybutylene terephthalate layer (4) outside the polycarbonate layer (3); and the weight ratio of the polycarbonate layer (3) to the polybutylene terephthalate layer (4) is 1.56-3.

96.

5. The central tube air-blowing micro cable according to claim 4, characterized in that: the weight ratio is 1.56-3.11; or the weight ratio is 3.11-3.

96.

6. The central tube air-blowing micro cable according to claim 4, characterized in that: the weight ratio is 1.56, 3.11 or 3.

96.

7. The central tube air-blowing micro cable according to claim 1 or 4, characterized in that: the polycarbonate layer is filled with a fiber paste (5) outside the optical fiber (1); the sheath (2) is made of polyethylene or low-smoke halogen-free material; and aramid yarn (6) is arranged between the co-extrusion jacket and the sheath (2).

8. The central tube air-blowing micro cable according to claim 1 or 4, characterized in that: the outer diameter of the sheath (2) is 2.1-3.8 mm, and the wall thickness is 0.3-0.5 mm; the optical fiber (1) has 1-36 fiber cores; and the diameter of the optical fiber (1) is 200 μm or 250 μm.

9. The central tube air-blowing micro cable according to claim 7, characterized in that: the air-blowing distance of the central tube air-blowing micro cable under air-blowing pressure is greater than 1250 m, and the air-blowing distance is measured under the condition that the temperature is 5-38 °C, the humidity is 30%-65%, and the air-blowing pipeline is 7 / 4 mm.

10. The central tube air-blowing micro cable according to claim 7, characterized in that: the lateral pressure resistance of the central tube air-blowing micro cable is greater than 1000 N, and the lateral pressure resistance is measured under the condition that the air-blowing distance is measured under the condition that the temperature is 5-38 °C, the humidity is 30%-65%, and the air-blowing pipeline is 7 / 4 mm. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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