Fireproof voice communication cable

Abstract

The invention relates to the technical field of cables, and particularly discloses a fireproof voice communication cable. According to the fireproof cable, the fireproof layer, the inner belting layer and the inner sheath layer are coated outside the plurality of strands of insulating single wires, and meanwhile, the fireproof layer, the outer belting layer and the outer sheath layer are coated outside the cable core formed by the plurality of strands of insulating wire groups, so that two sets of fireproof protection structures formed by the fireproof layer, the belting layer and the sheath layer are matched together; compared with a conventional fire-resistant cable, the fire-resistant cable provided by the invention has the advantages that the low wrapping and overlapping rate of the fire-resistant belt and the wrapping belt is maintained, so that the flexibility of the voice communication cable is ensured to meet the use requirement, and the service life of the cable is prolonged. And the total weight of the cable per unit length is reduced as much as possible, so that the aim of light weight is fulfilled.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a fire-resistant cable used in the field of voice communications. Background Art

[0002] Voice communication cables primarily include telephone lines and intercom cables. Compared to other types of cables, such as power cables or high-speed data cables, voice communication cables focus more on achieving the core goal of clear and stable transmission of analog voice signals. Therefore, they often have special requirements, such as excellent anti-interference capabilities to ensure clear signal transmission, sufficient mechanical strength and flexibility to ensure they can be bent according to routing requirements without damage, and so on.

[0003] In actual use, factors such as the use environment of voice communication cables will further put forward more requirements on the performance of the cables. For example, the communication cables used in the indoor horizontal wiring area of ​​the building's integrated wiring system need to have additional fire resistance to ensure smooth communication in the event of a disaster. On this basis, it is best to achieve the goal of lightweighting to reduce the burden on fixed structures such as mounting brackets.

[0004] Therefore, there is an urgent need for a fire-resistant voice communication cable that can meet various complex usage requirements. Summary of the Invention

[0005] The present invention provides a voice communication cable which has excellent fire resistance, good flexibility and low weight.

[0006] The present invention is achieved through the following technical solutions: A fire-resistant voice communication cable, in which an insulating layer is provided on the outside of the conductor to form an insulated single wire; a plurality of insulated single wires are twisted together and sequentially coated with at least an inner fire-resistant layer, an inner tape layer and an inner sheath layer from the inside out to form an insulated wire group; a plurality of insulated wire groups are twisted together to form a cable core; the gaps between the plurality of insulated wire groups are filled with low-smoke zero-halogen filling ropes; the wrapping overlap rate of the fire-resistant tape in the inner fire-resistant layer and the wrapping overlap rate of the inner tape in the inner tape layer are both not less than 35%; the cable core and the low-smoke zero-halogen filling ropes are sequentially coated with at least an outer fire-resistant layer, an outer tape layer and an outer sheath layer from the inside out, the wrapping overlap rate of the fire-resistant tape in the outer fire-resistant layer and the wrapping overlap rate of the outer tape in the outer tape layer are not less than 25%; when the number of conductors is less than 10 pairs, an intermediate sheath layer is further provided between the outer tape layer and the outer sheath layer.

[0007] In the present invention, a fire-resistant layer, an inner tape layer and an inner sheath layer are coated on the outside of several insulated single wires, and at the same time, a fire-resistant layer, an outer tape layer and an outer sheath layer are coated on the outside of the cable core composed of several insulated wire groups. In this way, the two sets of fire-resistant protection structures composed of "fire-resistant layer + tape layer + sheath layer" work together to achieve the protection effect of the core material conductor, so as to reduce the impact of burning on the conductor during a fire.

[0008] Based on the aforementioned fire-resistant protective structure, the present invention reduces the overlap ratio of the fire-resistant tape and wrapping tape compared to conventional existing fire-resistant cables, resulting in a wrapping ratio less than the 50% required for conventional fire-resistant cables. Typically, a reduction in the wrapping ratio reduces the fire resistance of structures such as the fire-resistant layer. However, the present invention compensates for this reduction in fire resistance through the coordination of two sets of fire-resistant protective structures, ensuring that the fire resistance performance of the voice communication cable of the present invention still meets the required performance. Furthermore, the reduction in the wrapping ratio improves the flexibility of the voice communication cable, meaning that the minimum bending radius during installation can be reduced to 10 times the cable diameter. This ensures the cable's fire resistance without compromising its installation and use requirements, such as flexibility, while maintaining its fire resistance. Furthermore, the reduction in the wrapping ratio reduces the total amount of fire-resistant tape and wrapping tape used per unit length (e.g., one meter), thereby minimizing the total weight of the cable per unit length and meeting the lightweighting goal.

[0009] As a further improvement of the present invention, the refractory tapes used in the inner refractory layer and the outer refractory layer are both mica tapes, and the inner and outer wrapping tapes are both copper plastic tapes.

[0010] Mica tape typically consists of at least a base material layer and a mica layer, with the mica layer providing high-temperature insulation to protect the conductors and other core materials within. Copper-plastic tape, on the other hand, typically consists of at least a carrier layer and a copper surface. The copper surface, on the one hand, acts as a shield by reflecting and absorbing external electromagnetic waves, thereby reducing external interference to the conductors in the cable when transmitting voice communications. On the other hand, the copper surface also acts as a heat transfer agent. In situations such as fires, the distribution of flames is uncontrollable, which can easily lead to severe heat exposure at certain points on the cable, causing them to quickly burn and break. However, the copper surface can quickly transfer heat from the core heated point to other parts, minimizing the temperature at that point and delaying the occurrence of severe heat exposure, resulting in burning and breakage of certain parts of the cable, and ultimately rendering the entire cable inoperable.

[0011] As a further improvement to the present invention, the mica layer of the mica tape and the copper surface of the copper plastic tape are both positioned on the side of the insulated single wire. The base layer of the mica tape and the carrier layer of the copper plastic tape are typically composed of polymer materials, such as polyimide or PET. These materials can minimize heat transfer in a fire environment. In particular, in the case of the copper plastic tape, they can work in conjunction with the copper surface to control the slow input of external heat and transfer and disperse the input heat. At room temperature, the base layer and carrier layer composed of polymer materials can provide a water and moisture barrier, protecting core materials such as the conductor.

[0012] As a further improvement of the present invention, the thickness of the mica tape is 15-18 mm, and the thickness of the copper plastic tape is 15-18 mm.

[0013] As a further improvement of the present invention, the inner sheath layer, the middle sheath layer and the outer sheath layer are all composed of low-smoke zero-halogen sheaths.

[0014] As a further improvement of the present invention, the thickness of the insulating layer is 0.53~0.70mm; the thickness of the inner sheath layer is 0.44~0.60mm; the thickness of the middle sheath layer is 0.62~0.80mm; if the number of conductors is less than 10 pairs, the thickness of the outer sheath layer is 0.50~0.60mm; if the number of conductors is greater than 10 pairs, the thickness of the outer sheath layer is 1.30~1.80mm.

[0015] The inventors have made adjustments to the thickness of each layer, so that under the premise of a reduced wrapping coverage rate, the layers can still achieve the required fire resistance after cooperating with each other, while avoiding the cable wall formed by the stacking of the layers being too thick, which affects the flexibility and other physical properties of the cable. In the present invention, a special optimization is made for small-sized cables with a small number of conductors. Among them, a new middle sheath layer is set for the cable under this specification, and the thickness of the middle sheath layer and the outer sheath layer are designed differently. On the one hand, for small-sized voice communication cables, there are relatively more bends involved during installation, and the actual separation of the outermost protective structure of the cable into the middle sheath layer and the outer sheath layer utilizes a double-layer interface structure to achieve stress dispersion on the outermost protective structure of the cable, thereby making the cable under this specification have better flexibility; at the same time, the protective structure formed by the two layers still has the required fire resistance, thereby achieving the goal of not reducing the fire resistance of the cable under this specification.

[0016] As a further improvement of the present invention, when the number of conductors is less than 10 pairs, a low-friction refractory material is filled between the middle sheath layer and the outer sheath layer.

[0017] As a further improvement to the present invention, the gaps between the insulated wires are filled with fiberglass yarn, with a diameter of 5 to 7 mm. The fiberglass yarn has high physical strength and excellent structural stability at high temperatures. Therefore, when the outer sheath burns or melts, the fiberglass yarn forms a skeleton network to support the conductor encased therein, preventing it from shifting. This prevents the conductor from collapsing and short-circuiting, thereby maintaining temporary continuity for voice communication.

[0018] As a further improvement of the present invention, a plurality of insulated single wires adopt a star-twisted structure, and the twisted pitch-diameter ratio is ≤10 times.

[0019] As a further improvement of the present invention, the pitch-diameter ratio of the plurality of insulated wires twisted together into a cable is 16 to 20 times. The above twisted pitch-diameter ratio ensures the reliability of the transmission performance of the fire-resistant cable and the tightness of its internal structure.

[0020] The beneficial effects of the present invention include: The two sets of fire-resistant protection structures in the cable, consisting of "fire-resistant layer + tape layer + sheath layer", work together to ensure that the cable still has strong fire resistance at a lower wrapping coverage rate; By controlling the structural layout and thickness of each layer, a balance between fire resistance and flexibility is achieved in the fire-resistant voice communication cable. This ensures that the cable has the required fire resistance to maintain uninterrupted voice communication in the event of a fire, while also having good flexibility to allow the cable to be bent according to design requirements. For cables of different sizes and specifications, their special performance requirements are met through partial structural adjustments, such as having stronger flexibility while ensuring fire resistance. This allows cables of different sizes and specifications to meet different usage needs, which is conducive to the promotion and use of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following drawings are provided for use in conjunction with preferred embodiments of the present invention to help understand the objects and advantages of the present invention, wherein: Figure 1 This is a schematic diagram of the structure of a fire-resistant voice communication cable. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and implementation examples.

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to illustrate the present invention, rather than to represent all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention. Example 1:

[0024] This embodiment provides a 6×2×0.2mm 2 Specifications of fire-resistant voice communication cable, where 6 represents a total of 6 pairs of conductors in the cable, 2 represents twisted pair, that is, the two conductors on the diagonal in the star-twisted structure are regarded as a working pair, and 0.2 represents the cross-sectional area of ​​each conductor is 0.2mm 2 .

[0025] like Figure 1 As shown, an insulating layer is provided outside each conductor to form an insulated single wire. The nominal thickness of the insulating layer is 0.7 mm, and the thinnest part is 0.63 mm. In this embodiment, the exemplary insulating layer adopts ceramic silicone. This type of silicone can achieve the insulation effect and can be ceramicized under high-temperature combustion conditions to form a hard ceramic protective layer, thereby protecting the conductor inside from melting, etc., so that voice communication transmission can continue.

[0026] like Figure 1 As shown, four insulated single wires are twisted together in a star-shaped twist structure with a pitch-to-diameter ratio of 9. Subsequently, the four twisted insulated single wires are sequentially coated with an inner refractory layer, an inner tape layer, and an inner sheath layer from the inside out to form an insulated wire assembly. In this embodiment, the inner refractory layer is formed by wrapping calcined mica tape with a thickness of 15 mm and a wrapping overlap of 35%, with the mica layer facing inward, i.e., toward the side where the insulated single wires are located. The inner tape layer is formed by wrapping copper plastic tape with a thickness of 15 mm and a wrapping overlap of 35%, with the copper surface facing inward, i.e., toward the side where the insulated single wires are located. The inner sheath layer is extruded from a low-smoke halogen-free material, exemplarily using the commercially available HW495-2 material. The inner sheath layer has a nominal thickness of 0.6 mm and a thinnest point of 0.5 mm.

[0027] like Figure 1 As shown, three insulated wire groups are twisted together to form a cable core, wherein the pitch diameter ratio of the twisted cable is 18 times; the gaps between the three insulated wire groups are filled with low-smoke halogen-free filling ropes, which are illustratively made of commercially available material of model HW495-2.

[0028] The cable core and the low-smoke halogen-free filling rope are covered with an outer fire-resistant layer, an outer tape layer, a middle sheath layer and an outer sheath layer in sequence from the inside out. In this embodiment, the inner fire-resistant layer is formed by wrapping a calcined mica tape with a thickness of 15 mm and a wrapping overlap of 30%. When wrapping, the mica layer faces inward, that is, toward the side where the insulated single wire is located; the outer tape layer is formed by wrapping a copper plastic tape with a thickness of 15 mm and a wrapping overlap of 30%. When wrapping, the copper surface faces inward, that is, toward the side where the insulated single wire is located; the middle sheath layer is formed by extruding a low-smoke halogen-free material. For example, the low-smoke halogen-free material adopts the commercially available model HW495-2. The nominal thickness of the middle sheath layer is 0.8 mm, and the thinnest The outer sheath layer is formed by extrusion of low-smoke halogen-free material. For example, the low-smoke halogen-free material adopts the commercially available model FHW162-3. The average thickness of the outer sheath layer is 0.6mm, and the thinnest part is 0.55mm. The middle sheath layer and the outer sheath layer are filled with low-friction refractory material. In this embodiment, talcum powder is used. This material can not only reduce the friction between the middle sheath layer and the outer sheath layer so that the two can slide relative to each other to relieve stress, but also have a flame retardant effect to further protect the conductors and other materials in the cable during combustion. Example 2:

[0029] This embodiment provides a 20×2×0.2mm 2 Specifications of fire-resistant voice communication cable, where 20 represents a total of 6 pairs of conductors in the cable, 2 represents twisted pair, that is, the two conductors on the diagonal in the star-twisted structure are regarded as a working pair, and 0.2 represents the cross-sectional area of ​​each conductor is 0.2mm 2 .

[0030] Each conductor is covered with an insulating layer to form an insulated wire. The nominal thickness of this layer is 0.7 mm, with a minimum thickness of 0.59 mm. In this embodiment, the insulating layer is made of ceramic silicone. Four insulated wire strands are twisted together in a star-twisted configuration with a pitch-to-diameter ratio of 10. The four strands are then coated with an inner fire-resistant layer, an inner tape layer, and an inner sheath layer, sequentially from the inside out, to form an insulated wire assembly. In this embodiment, the inner refractory layer is formed by wrapping a calcined mica tape, the thickness of the calcined mica tape is 16 mm, the wrapping overlap rate is 38%, and the mica layer faces inward when wrapping, that is, toward the side where the insulated single wire is located; the inner wrapping tape layer is formed by wrapping a copper plastic tape, the thickness of the copper plastic tape is 15 mm, and the wrapping overlap rate is also 36%. When wrapping, the copper surface faces inward, that is, toward the side where the insulated single wire is located; the inner sheath layer is extruded from a low-smoke halogen-free material. For example, the low-smoke halogen-free material uses a commercially available model HW495-2 material. The nominal thickness of the inner sheath layer is 0.6 mm, and the thinnest part is 0.45 mm.

[0031] Five insulated wire strands are twisted together to form a cable core, wherein the pitch diameter ratio of the twisted strands is 17 times; the gaps between the five insulated wire strands are filled with low-smoke halogen-free filling ropes and glass fiber yarns with a diameter of 6 mm. For example, the low-smoke halogen-free filling ropes are also made of commercially available material with model HW495-2.

[0032] The cable core and low-smoke, zero-halogen (LSZH) filling rope are coated, from the inside out, with an outer refractory layer, an outer tape layer, and an outer sheath layer. In this embodiment, the inner refractory layer is formed by wrapping calcined mica tape with a thickness of 15 mm and a wrapping overlap of 27%, with the mica layer facing inward, i.e., toward the side where the insulated wires are located. The outer tape layer is formed by wrapping copper plastic tape with a thickness of 15 mm and a wrapping overlap of 32%, with the copper surface facing inward, i.e., toward the side where the insulated wires are located. The outer sheath is extruded from a low-smoke, zero-halogen (LSZH) material, exemplified by the commercially available FHW162-3 material. The average thickness of the outer sheath is 1.5 mm, with a minimum thickness of 1.34 mm.

[0033] Performance testing: In this embodiment, the fire-resistant voice communication cables in Examples 1 and 2 are tested for their mechanical properties and fire resistance. The cable mechanical property test is carried out with reference to the test method described in "General test methods for insulation and sheathing materials of electric and optical cables - Part 11: General test methods for thickness and dimensions - Mechanical properties test" (GB / T 2951.11-2008). The fire resistance performance-related test items are carried out with reference to the test methods described in "Burning tests for electric and optical cables under flame conditions - Part 12: Vertical flame spread test for single insulated wires and cables - 1kW premixed flame test method" (GB / T 18380.12-2022), the International Electrotechnical Commission (IEC) standard IEC 60332-1-2 Vertical burning performance test for electric wires and cables, and "Line integrity tests for cables or optical cables under flame conditions - Part 21: Test procedures and requirements for cables with rated voltages of 0.6 / 1.0 kV and below" (GB / T 19216.21-2003). The relevant test results of the two groups of cables in Examples 1 and 2 are shown in Table 1.

[0034] Table 1 Mechanical and combustion performance test results of cables , It can be seen from the above test results that the fire-resistant voice communication cables in Examples 1 to 2 meet the physical performance requirements as cables, and at the same time have the required fire resistance, which can meet the daily use needs of voice communication cables; that is, in the present invention, the inventor arranges the positions of the fire-resistant layer, the wrapping layer and other layers, adjusts the thickness, adjusts the wrapping coverage rate and other means, so that the layers in the cable can cooperate with each other to exert the required fire-resistant effect, and at the same time avoids the cable wall being too thick to affect the physical properties such as the flexibility of the cable, so that the prepared cable meets the relevant requirements of the use environment such as the indoor horizontal wiring area of ​​the building's integrated wiring system.

[0035] Finally, it should be noted that the above implementation cases are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above implementation cases, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above implementation cases, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the implementation cases of the present invention.

Claims

1. A fire-resistant voice communication cable, characterized by: An insulating layer (1-2) is provided outside the conductor (1-1) to form an insulated single wire (1); Several strands of the insulating single wires (1) are twisted together and sequentially covered with at least an inner fire-resistant layer (2-1), an inner tape layer (2-2) and an inner sheath layer (2-3) from the inside out to form an insulating wire group (2); several strands of the insulating wire group (2) are twisted together to form a cable core (3); and gaps between several strands of the insulating wire group (2) are filled with low-smoke halogen-free filling ropes (3-1); wherein the wrapping overlap rate of the fire-resistant tape in the inner fire-resistant layer (2-1) and the wrapping overlap rate of the inner tape in the inner tape layer (2-2) are both not less than 35%; The cable core (3) and the low-smoke zero-halogen filling rope (3-1) are at least sequentially coated with an outer fire-resistant layer (4-1), an outer tape layer (4-2) and an outer sheath layer (4-4) from the inside out, wherein the wrapping overlap rate of the fire-resistant tape in the outer fire-resistant layer (4-1) and the wrapping overlap rate of the outer tape in the outer tape layer (4-2) are not less than 25%; When the number of the conductors (1-1) is less than 10 pairs, a middle sheath layer (4-3) is further provided between the outer tape layer (4-2) and the outer sheath layer (4-4).

2. A fire-resistant voice communication cable according to claim 1, characterized in that: The refractory tapes used in the inner refractory layer (2-1) and the outer refractory layer (4-1) are both mica tapes, and the inner wrapping tape and the outer wrapping tape are both copper plastic tapes.

3. A fire-resistant voice communication cable according to claim 2, characterized in that: The mica layer on the mica tape and the copper surface of the copper plastic tape are both placed on the side where the insulated single wire (1) is located.

4. A fire-resistant voice communication cable according to claim 2, characterized in that: The thickness of the mica tape is 15-18 mm, and the thickness of the copper plastic tape is 15-18 mm.

5. A fire-resistant voice communication cable according to any one of claims 1 to 4, characterized in that: The inner sheath layer (2-3), the middle sheath layer (4-3) and the outer sheath layer (4-4) are all composed of low-smoke zero-halogen sheaths.

6. A fire-resistant voice communication cable according to claim 5, characterized in that: The thickness of the insulating layer (1-2) is 0.53-0.70 mm; the thickness of the inner sheath layer (2-3) is 0.44-0.60 mm; the thickness of the middle sheath layer (4-3) is 0.62-0.80 mm; if the number of the conductors (1-1) is less than 10 pairs, the thickness of the outer sheath layer (4-4) is 0.50-0.60 mm; if the number of the conductors (1-1) is greater than 10 pairs, the thickness of the outer sheath layer (4-4) is 1.30-1.80 mm.

7. A fire-resistant voice communication cable according to claim 1, characterized in that: When the number of the conductors (1-1) is less than 10 pairs, a low-friction refractory material is filled between the middle sheath layer (4-3) and the outer sheath layer (4-4).

8. A fire-resistant voice communication cable according to claim 1, characterized in that: The gaps between the insulating wire groups (2) are also filled with glass fiber yarns, and the diameter of the glass fiber yarns is 5-7 mm.

9. A fire-resistant voice communication cable according to claim 1, characterized in that: The plurality of insulated single wires (1) adopt a star-twisted structure, and the twisted pitch-diameter ratio is ≤10 times.

10. A fire-resistant voice communication cable according to any one of claims 1 or 9, characterized in that: The pitch-to-diameter ratio of a plurality of strands of the insulated wire group (2) twisted into a cable is 16 to 20 times.

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