Fireproof coaxial cable

Abstract

The present invention relates to a fireproof coaxial cable which is capable of stably maintaining a communication function for a predetermined period of time by being provided with an insulator that can maintain the shapes of an inner conductor and an outer conductor at a high temperature of 750°C or higher in the event of a fire. According to the present invention, the fireproof coaxial cable comprises: an inner conductor disposed in the center portion; an insulator transversely wound around the outside of the inner conductor; an outer conductor surrounding the outside of the insulator and forming a coaxial structure with the inner conductor; and a cable jacket surrounding the outside of the outer conductor, wherein the insulator includes an insulating core and a fireproof layer surrounding the insulating core, and the fireproof layer includes silicone rubber.

Description

Fireproof coaxial cable

[0001] The present invention relates to a fire-resistant coaxial cable. More specifically, the present invention relates to a fire-resistant coaxial cable capable of stably maintaining communication functions for a certain period of time at high temperatures of 750°C or higher in the event of a fire.

[0002] Materials such as PE and PTFE, which are used as insulators in general coaxial cables, have a melting point of 100 to 325°C, which means that they melt in a fire environment of at least 750°C or higher, and there is a problem that they cannot sufficiently perform the insulating role between the inner and outer conductors.

[0003] Therefore, in a fire environment, a structure between the inner conductor and the outer conductor is maintained to secure insulation performance so that communication functions can be maintained for a certain period of time, and at the same time, a fire-resistant coaxial cable including an insulation structure that forms a concentric circle between the inner conductor and the outer conductor and has a dielectric constant equivalent to that of materials such as PE and PTFE so that the communication cable can faithfully perform its role as a transmission line even in an environment where there is no fire is required.

[0004] In particular, firefighting wireless communication auxiliary equipment is essential to be installed in high-rise and large buildings. In order to provide smooth wireless communication for firefighters at the scene of a fire in the event of a fire, it is desirable that the fire-resistant coaxial cable used in the firefighting wireless communication auxiliary equipment satisfies the fire resistance performance according to the standards IEC 60331-11 and IEC 60331-23. IEC 60331-11 and IEC 60331-23, which are fire resistance standards for fire-resistant coaxial cables, evaluate whether there is a short circuit between the inner conductor and the outer conductor for a certain period of time when a test voltage is applied at a flame temperature of at least 750℃.

[0005] Accordingly, a fire-resistant coaxial cable is required that can stably maintain its function for a certain period of time at high temperatures of 750℃ or higher when a fire occurs, so that it can be used as a coaxial cable for auxiliary firefighting wireless communication equipment.

[0006] The present invention aims to provide a fire-resistant coaxial cable capable of stably maintaining communication functions for a certain period of time at a high temperature of 750°C or higher when a fire occurs.

[0007] In order to solve the above problem, the present invention can provide a fire-resistant coaxial cable including: an inner conductor disposed in a central portion; an insulator wound transversely around the outer side of the inner conductor; an outer conductor wrapping around the outer side of the insulator and forming a coaxial structure with the inner conductor; and a cable jacket wrapping around the outer side of the outer conductor; wherein the insulator has an insulating core and a fire-resistant layer wrapping the insulating core, and the fire-resistant layer includes silicone rubber.

[0008] In addition, in order to solve the above problem, the present invention can provide a fire-resistant coaxial cable including an inner conductor disposed in a central portion; an insulator wound transversely around the outer side of the inner conductor; an outer conductor wrapping around the outer side of the insulator and forming a coaxial structure with the inner conductor; and a cable jacket wrapping around the outer side of the outer conductor; wherein the insulator has an insulating core and a refractory layer wrapping the insulating core, and the refractory layer includes a refractory elastomer.

[0009] In addition, in order to solve the above problem, the present invention can provide a fire-resistant coaxial cable including: an inner conductor disposed in a central portion; an insulator wound transversely around the outer side of the inner conductor; an outer conductor wrapping around the outer side of the insulator and forming a coaxial structure with the inner conductor; and a cable jacket wrapping around the outer side of the outer conductor; wherein the insulator has an insulating core and a fire-resistant layer wrapping the insulating core, and the insulating core of the insulator includes polyethylene, and the fire-resistant layer of the insulator includes at least one or more of basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape.

[0010] And, the refractory layer of the above insulator may include silicone rubber.

[0011] Here, the insulating core of the insulator may include a tensile member.

[0012] In this case, the tensile strength of the insulating core including the above tensile member may be 5 g / TEX or more.

[0013] And, the tensile member may include at least one of basalt fiber, glass fiber, silica fiber, ceramic fiber, or aramid fiber materials.

[0014] Additionally, the tensile member may include glass yarn.

[0015] In addition, the temperature at which the shape deformation of the insulating core occurs may be higher than that of the refractory layer.

[0016] Here, when the outer conductor of the refractory coaxial cable having a length of 500 mm is fixed and the inner conductor is pulled in the axial direction of the inner conductor at a speed of 50.0 mm / min, the maximum load applied may be 2 kgf or more.

[0017] In this case, the insulator may be wrapped and include a low-dielectric constant layer having a dielectric constant of 2.5 or less.

[0018] In addition, the low-k dielectric layer may include at least one of PE (Polyethylene), HDPE (High-Density Polyethylene), PTFE (Polytetrafluoroethylene), and FEP (Fluorinated ethylene propylene).

[0019] And, it may include an insulating refractory reinforcing layer that surrounds the insulator and reinforces the refractory performance of the refractory coaxial cable.

[0020] Here, the insulating refractory reinforcing layer may include at least one of basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape.

[0021] In this case, in order to reinforce the fire resistance performance of the fire-resistant coaxial cable, one or more layers of fire-resistant tape may be further included to wrap the outer side of the outer conductor.

[0022] And, the refractory tape layer may include at least one of a mica tape, a glass tape, and a metal tape.

[0023] Additionally, in order to enhance the fire resistance performance of the fire-resistant coaxial cable, a conductor fire-resistant reinforcement layer surrounding the inner conductor may be further included.

[0024] And, the conductor refractory reinforcing layer may include at least one of basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape.

[0025] Here, the inner conductor and the outer conductor may be made of copper or a copper alloy material.

[0026] In this case, the external conductor may have a corrugated pipe structure in which corrugated mountains and corrugated valleys are repeatedly formed.

[0027] According to the fire-resistant coaxial cable according to the present invention, the insulator arranged between the inner conductor and the outer conductor includes a fire-resistant layer made of a specific fire-resistant material and an insulating core embedded therein, and can realize excellent fire-resistant performance by maintaining insulation between the inner conductor and the outer conductor at a high temperature of 750°C or higher when a fire occurs.

[0028] In addition, according to the fire-resistant coaxial cable according to the present invention, the insulator is arranged to be horizontally wound on the outside of the inner conductor to form an air layer, and a low-dielectric-constant layer is added on the outside of the insulator to secure a low dielectric constant, thereby enabling the implementation of excellent communication performance of the fire-resistant coaxial cable.

[0029] In addition, according to the fire-resistant coaxial cable of the present invention, the fire-resistant characteristics can be further improved by adding an insulating fire-resistant reinforcing layer to the outside of the insulator.

[0030] Figure 1 illustrates a configuration diagram of a firefighting wireless communication auxiliary equipment including a fire-resistant coaxial cable according to the present invention.

[0031] Figure 2 illustrates a multi-stage stripped perspective view of one embodiment of a fire-resistant coaxial cable according to the present invention.

[0032] Figure 3 shows a partially enlarged cutaway view of the refractory coaxial cable illustrated in Figure 2.

[0033] FIG. 4 illustrates a cross-sectional view of one embodiment of the refractory coaxial cable illustrated in FIG. 2.

[0034] Figure 5 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0035] Figure 6 shows the pulling force test results for the specimens of Examples 1 to 3 and Comparative Examples 1 to 3.

[0036] Figure 7 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0037] Figure 8 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0038] Figure 9 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0039] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosure is thorough and complete, and to sufficiently convey the spirit of the invention to those skilled in the art. Like reference numbers designate like elements throughout the specification.

[0040] Figure 1 illustrates a configuration diagram of a firefighting wireless communication auxiliary equipment including a fire-resistant coaxial cable according to the present invention.

[0041] As illustrated in FIG. 1, the auxiliary equipment for firefighting wireless communication may include a fire-resistant coaxial cable (100) constituting a wired communication network, a fire-resistant leaky coaxial cable (100L) constituting a wireless communication network, an indoor antenna (200) for transmitting and receiving wireless signals to and from a wireless terminal (t) carried by a firefighter, a central amplifier (300) installed in a disaster prevention room (d) or the like for amplifying and relaying wireless signals transmitted and received, a line amplifier (400) for amplifying signals on a transmission and reception line, a distributor (500) for distributing signals, an outdoor antenna (600) for transmitting and receiving wireless signals to and from a wireless terminal (t) outside a building, a power supply device (700) for supplying power to the line amplifier (400), etc.

[0042] As illustrated in FIG. 1, the auxiliary fire-fighting wireless communication equipment may be equipped with a fire-resistant coaxial cable (100) for constructing a wired communication network composed of various equipment used for fire prevention and disaster prevention, such as an indoor antenna (200), a central amplifier (300), a line amplifier (400), a distributor (500), an outdoor antenna (600), a power supply device (700), and lines connecting them. In addition, a fire-resistant leakage coaxial cable (100L) may be laid in an underground space, such as an underground parking lot, where the area inside a building is wide and the space is not partitioned, to construct a wireless communication network. Of course, if necessary, not only the fire-resistant leakage coaxial cable but also the indoor antenna (200) may be installed in the underground space of a building.

[0043] For reference, according to the fire safety standards for wireless communication auxiliary equipment (NFSC 505), the leaky coaxial cable and indoor antenna (200) can transmit and receive electromagnetic waves in the range of 440 MHz to 450 MHz, which is a fire communication frequency.

[0044] This type of wireless communication network can enable communication between firefighters and the fire command center or control room.

[0045] The above fire-fighting wireless communication auxiliary equipment is installed above and below ground of the building (b) and may be equipped with multiple indoor antennas (200) capable of wireless communication with each wireless terminal (t) carried by firefighters.

[0046] The above indoor antenna (200) can be installed in the indoor space of each floor of the building (b), and enables mutual communication between firefighters carrying wireless terminals (t) or between firefighters carrying wireless terminals (t) and personnel within the fire prevention room (d).

[0047] Here, the indoor antenna (200) can be connected to the central amplifier (300) of the fire prevention room (d) located within the building (b) via a fire-resistant coaxial cable (100).

[0048] In addition, the above fire-fighting wireless communication auxiliary equipment may be configured to include a plurality of line amplifiers (400) that are connected to the indoor antenna (200) via a fire-resistant coaxial cable (100) and amplify signals transmitted and received from the indoor antenna (200).

[0049] In addition, the firefighting wireless communication auxiliary equipment illustrated in FIG. 1 may be configured to include a plurality of distributors (500) for branching signals transmitted and received from a plurality of indoor antennas (200).

[0050] The above-mentioned distributor (500) may be provided in each area where a signal is branched into multiple coaxial cables, and the distributor (500) may synthesize a signal received from the indoor antenna (200) or branch a signal provided from a central amplifier and transmit each branched signal to the indoor antenna (200).

[0051] In addition, the above fire-fighting wireless communication auxiliary equipment may be configured to include an outdoor antenna (600) installed outdoors. The outdoor antenna (600) enables voice communication between a wireless terminal (t) carried by a firefighter or fire commander outside a building and a firefighter inside a building or communication with a central amplifier (300) in a fire prevention room (d).

[0052] Here, even if the outdoor antenna (600) is not installed, the firefighting wireless communication auxiliary equipment can be connected by wire to a wireless terminal (t) carried by a firefighter or fire commander outside the building to enable voice communication with firefighters inside the building or communication with the central amplifier (300) of the fire prevention room (d).

[0053] In addition, the above fire-fighting wireless communication auxiliary equipment may be configured to include a power supply device (700) for supplying commercial power or emergency power. The power supply device (700) may provide power to a line amplifier (400) or the like through a fire-resistant coaxial cable (100) or a separate power cable.

[0054] Meanwhile, the overall configuration of the fire-fighting wireless communication auxiliary equipment to which the fire-resistant coaxial cable (100) according to the present invention is applied is not limited to the configuration shown in FIG. 1, and may be configured by selectively combining at least some of the indoor antenna (200), central amplifier (300), line amplifier (400), distributor (500), outdoor antenna (600), and power supply device (700), or may be configured by additionally including various equipment constituting a typical fire-fighting wireless communication auxiliary equipment in addition to the configuration described above.

[0055] Meanwhile, although an example in which a fire-resistant coaxial cable (100) according to the present invention is applied to a firefighting wireless communication auxiliary device is presented through FIG. 1, the fire-resistant coaxial cable according to the present invention can be applied to various environments in which it is necessary to maintain a communication function when a high temperature occurs.

[0056] Hereinafter, the structure of the fire-resistant coaxial cable (100) according to the present invention will be examined in detail with reference to FIG. 2 and below.

[0057] FIG. 2 illustrates a multi-stage stripped perspective view of one embodiment of a fire-resistant coaxial cable according to the present invention, FIG. 3 illustrates a partial enlarged cutaway view of the fire-resistant coaxial cable illustrated in FIG. 2, and FIG. 4 illustrates a cross-sectional view of the fire-resistant coaxial cable illustrated in FIG. 2.

[0058] As illustrated in FIGS. 2 to 4, a fire-resistant coaxial cable (100) according to the present invention may be configured to include an inner conductor (10) disposed at a central portion; an insulator (20) wound transversely around the outer side of the inner conductor (10), including an insulating core (21) and a fire-resistant layer (23) made of a refractory composition and wrapping the insulating core (21); an outer conductor (30) wrapping the outer side of the insulator (20) and forming a coaxial structure with the inner conductor (10); and a cable jacket (40) wrapping the outer side of the outer conductor (30).

[0059] The inner conductor (10) is provided at the center and serves to transmit communication signals. Typically, copper or aluminum is used as the material for the inner conductor (10) of a coaxial cable. However, since the melting point of copper is 1,084°C, while the melting point of aluminum is 660°C, the inner conductor (10) is preferably made of copper or a copper alloy material. The cross-section of the inner conductor (10) is circular and the diameter can be configured to be 5.0 millimeters (mm) or less.

[0060] An insulator (20) is provided on the outside of the inner conductor (10), and the insulator (20) is configured in the form of a rope or wire and may be provided in a transversely wound manner with a preset pitch range on the outside of the inner conductor (10). The insulator (20) maintains a constant gap between the inner conductor (10) and the outer conductor (30) and serves to insulate the inner conductor (10). The insulator (20) may be configured to include an insulating core (21) and a fire-resistant layer (23), and the insulating core (21) is configured in the form of a rope, wire, or a long, elongated fiber, and the fire-resistant layer (23) is provided in a form that wraps the insulating core (21) with a constant thickness, so that the insulator (20) may be implemented in the form of a rope or wire.

[0061] In this way, the fire-resistant coaxial cable (100) according to the present invention is not formed in a form in which the insulator (20) is entirely filled around the outer circumference of the inner conductor (10) as in the past, but is formed in the form of a rope or wire and spirally wound around the outer side of the inner conductor (10), thereby reducing the cross-sectional area of ​​the insulator (20), and thus reducing the absolute amount of the insulator (20), which is relatively weak in fire resistance compared to the inner conductor (10) and the outer conductor (30), thereby improving the flame retardancy, while improving the flexibility of the cable and minimizing the cable manufacturing cost, and stably maintaining the coaxial structure between the inner conductor (10) and the outer conductor (30) through the insulator (20).

[0062] Furthermore, since the insulator (20) is configured in a shape that is transversely wound on the outside of the inner conductor (10), an empty space is formed between the inner conductor (10) and the outer conductor (30), and the dielectric constant of the space between the inner conductor (10) and the outer conductor (30) is reduced by the air layer of the empty space formed around the insulator (20), thereby improving the transmission characteristics of the electromagnetic wave signal transmitted and received through the fire-resistant coaxial cable (100).

[0063] The above insulator (20) itself has a high permittivity, but by winding it transversely on the outer surface of the inner conductor (10) to include an air layer, the permittivity of the entire insulating structure between the inner conductor (10) and the outer conductor (30) of the fire-resistant coaxial cable can be lowered. In addition, as described below with reference to FIG. 5 and below, a low permittivity layer (50) can be further included on the outside of the insulator (20) to lower the permittivity of the insulating structure. At this time, the dielectric constant of the low permittivity layer (50) is preferably 2.5 or less. When the low permittivity layer (50) is formed on the outside of the insulator (20), the permittivity of the fire-resistant coaxial cable can be further lowered, thereby reducing the signal attenuation of the fire-resistant coaxial cable. A detailed description of the low permittivity layer (50) will be postponed.

[0064] Specifically, the inclination angle (θ) at which the insulator (20) is wound transversely around the outer side of the inner conductor (10) may be 20 to 60°. The inclination angle (θ) may be defined as the angle between the base and the hypotenuse of a right triangle having a base equal to half the pitch (P) of the insulator (20) when wound transversely as illustrated in FIG. 3 and a height equal to the inner diameter (D) of the outer conductor (30). The inner diameter (D) of the outer conductor (30) may be the inner diameter between the valleys of the wrinkles in the outer conductor (30) in which wrinkles are formed.

[0065] Here, if the above-mentioned inclination angle (θ) exceeds 60°, the structure of the cable is stable, but the dielectric constant between the inner conductor (10) and the outer conductor (30) increases due to the insulator (20), so that the communication characteristics of the cable deteriorate, the cable becomes excessively stiff, so that the flexibility deteriorates, and the manufacturing cost may increase due to an unnecessary increase in material costs.

[0066] On the other hand, when the above-mentioned inclination angle (θ) is less than 20°, the manufacturing cost is reduced due to the reduction in material cost, and the communication characteristics are improved due to the lower dielectric constant, but the cable is structurally unstable, such as the outer conductor being easily crushed when bent, and a short circuit may occur due to the inner conductor and outer conductor coming into contact.

[0067] Meanwhile, the outer diameter of the insulator (20) may be 75 to 95% of the diameter of the inner conductor (10). Here, if the outer diameter of the insulator (20) is less than 75% of the diameter of the inner conductor (10), it is difficult to secure a gap between the inner conductor (10) and the outer conductor (30) to satisfy the characteristic impedance of 50±5 Ω, and if it is more than 95%, when the insulator (20) is horizontally wound on the outside of the inner conductor (10), excessive tension may be applied to the inner conductor (10), making it difficult for the inner conductor (10) to maintain a straight line in the longitudinal direction, which may deteriorate structural stability.

[0068] Detailed experimental results of the above insulator (20) structure will be described below.

[0069] Meanwhile, fire-resistant coaxial cables for signal transmission within firefighting radio communication auxiliary equipment should preferably satisfy the fire resistance performance specified in international standards IEC 60331-11 and IEC 60331-23. As mentioned above, standards IEC 60331-11 and IEC 60331-23 assess whether there is a short circuit between the inner and outer conductors when a test voltage is applied at a flame temperature of at least 750°C.

[0070] Accordingly, in order to satisfy the fire resistance performance according to the standards IEC 60331-11 and IEC 60331-23, the fire-resistant coaxial cable (100) according to the present invention can be designed so that the insulator (20) constituting the fire-resistant coaxial cable (100) can secure excellent fire resistance performance at a high temperature of 750°C or higher when a fire occurs, while at the same time being able to maintain the internal structure of the insulator at a high temperature.

[0071] In addition, the fire-resistant coaxial cable (100) including the insulator (20) includes an inner conductor (10) of high conductivity, an insulator (20) of low dielectric constant, and an outer conductor (30) of high conductivity so that the inherent function of the communication cable can be properly performed even in an environment where no fire occurs, and can be designed and manufactured to maintain a constant structure between the inner conductor (10) and the outer conductor (30).

[0072] The insulator (20) constituting the fire-resistant coaxial cable (100) according to the present invention may be configured to include an insulating core (21) formed by being embedded along the longitudinal direction and a fire-resistant layer (23) made of a fire-resistant elastomer material and surrounding the insulating core (21).

[0073] The above-mentioned refractory layer (23) may be a refractory elastomer material. For example, the refractory layer may include at least one of silicone rubber, fluoroelastomer (FKM), fluorosilicone (FVMQ), ethylene acrylic rubber (AEM), and acrylic rubber (ACM). When the refractory layer (23) is a refractory elastomer material, it is easily deformable, so that when the insulator (20) is horizontally wound around the outside of the inner conductor (10), the insulator (20) can be in close contact with the outer surface of the inner conductor (10). In this way, the insulator (20) provides close contact according to the material properties, so that the coaxial structure between the outer conductor and the inner conductor can be stably maintained even when the refractory coaxial cable is bent or subjected to stress due to an external force.

[0074] The adhesion of the above insulator (20) can be confirmed through a pulling force test.

[0075] The pulling force test prepares a 500 mm long fire-resistant coaxial cable specimen, and while fixing the outer conductor (30), pulls the inner conductor (10) in the axial direction of the inner conductor (10) at a speed of 50.0 mm / min. The pulling load is determined as the maximum load at which the pulling load is maximum.

[0076] In this case, when the refractory layer (23) is configured to include a refractory elastomer material, the maximum load may be at least 2 kgf. When the maximum load is less than 2 kgf, the outer conductor (30) and the inner conductor (10) are easily separated with a small force, so that structural damage between the inner conductor (10) and the outer conductor (30) may easily occur due to an external tensile force, and the reliability of the cable cannot be guaranteed during installation and use.

[0077] When the above insulator (20) is composed mainly of refractory materials such as basalt, ceramic, or glass, there is a problem in that the insulator is easily cracked and damaged when it is horizontally wound on the outside of the inner conductor (10) due to insufficient flexibility, the adhesion between the inner conductors is poor, and when the insulator is formed by weaving it in the form of a fiber, it is not easy to achieve sufficient thickness.

[0078] On the other hand, when silicone rubber is applied as the refractory elastomer material constituting the refractory layer (23), it was confirmed that the processability during manufacturing was excellent, so that it was easy to implement the thickness in the shape of the insulator, and the workability of the product processed into the shape of the insulator was excellent, so that the adhesion was better when horizontally wound on the outside of the inner conductor (10).

[0079] Specifically, when a pulling force test was performed to measure the adhesion of the above-mentioned insulator (20) manufactured using the above-mentioned silicone rubber as the main material, with a specimen length of 500 mm and a test speed of 50.0 mm / min for a refractory coaxial cable, the maximum load was measured to be 16.2 kgf, confirming that the insulator (20) was sufficiently adhered to the outer surface of the inner conductor (10) and the inner surface of the outer conductor (30), respectively.

[0080] In addition, silicone rubber has far superior fire resistance performance compared to general elastic polymer materials, and as a thermosetting material, it is hardened at high temperatures, so that the separation structure between the inner conductor (10) and the outer conductor (30) can be maintained even in a high temperature environment, thereby allowing the fire-resistant coaxial cable to maintain its function.

[0081] The above-mentioned refractory layer (23) can be formed to have a circular cross-section on the outside of the insulating core (21) by extruding a refractory elastomer material, etc. As an example of the refractory elastomer material constituting the above-mentioned refractory layer (23), it can be formed by adding various refractory fillers, such as magnesium hydroxide (MDH), aluminum hydroxide (ATH), mineral powders such as quartz or wollastonite, mineral fibers, and glass fibers, to silicone rubber as a base resin.

[0082] Silicone rubber, as the above-mentioned refractory elastomer material, may be a polymer in which silicon (Si) and oxygen containing organic groups are chemically bonded to each other through siloxane bonds. This siloxane bond exhibits excellent bonding stability at high temperatures, making it suitable as a refractory material. In addition, silicone rubber has a relatively low heat release rate and does not emit toxic gases when burned, making it an advantageous environmentally friendly refractory material.

[0083] The refractory silicone rubber as a refractory elastomer material constituting the refractory layer (23) may include a silicone rubber as a base resin and a refractory filler, and thus, even if the refractory coaxial cable (100) is placed in a high-temperature environment and the silicone rubber is partially thermally decomposed, oxidized, or burned, sufficient refractory performance can be implemented to maintain the separation structure between the inner conductor (10) and the outer conductor (30) of the refractory coaxial cable (100).

[0084] Meanwhile, since the refractory silicone rubber constituting the refractory layer (23) has relatively high flexibility and ductility, the refractory layer (23) may be deformed, such as by stretching, during the process of horizontally winding the insulator (20) on the outside of the inner conductor (10).

[0085] Accordingly, the insulator (20) has an insulating core (21) in the shape of a long wire, rope or thread embedded inside, so that tension can be applied in the longitudinal direction when the insulator (20) is wound horizontally, thereby preventing the sagging of the refractory layer (23).

[0086] To provide the above tension, the insulating core (21) may be configured to include a tensile member. The tensile member may be formed by including a fiber yarn such as a reinforcing fiber, for example, basalt fiber, glass fiber, silica fiber, ceramic fiber, or aramid fiber material. Among these, it may particularly include glass yarn, which has high fire resistance and is easy to process.

[0087] The glass yarn constituting the above insulating core (21) can be formed by twisting fine inorganic glass fibers of 5 μm to 13 μm obtained by melt spinning refined raw materials at a high temperature of 1,200 to 1,500°C into a yarn shape by focusing hundreds of them.

[0088] The above insulating core (21) has a long fiber, wire or rope shape to maintain the shape of the insulator (20) and reinforce the tensile strength, and includes a tensile member, so that it can have a tensile strength higher than that of the fire-resistant layer (23), and preferably, the tensile strength may be 5 g / TEX or more. The tensile strength of the insulating core (21) including the tensile member may be a value measured by the ASTM D885 standard test method. When the tensile strength of the insulating core (21) is less than 5 g / TEX, the insulator (20) including the fire-resistant layer (23) as a main component, which is an elastomeric material, easily stretches and deforms, making it difficult to maintain a constant coaxial structure between the inner conductor and the outer conductor in the cable manufacturing and use environment.

[0089] The outer diameter of the insulating core (21) may be 30% or less of the outer diameter of the refractory layer (23). If the outer diameter of the insulating core (21) is 30% or more of the outer diameter of the refractory layer (23), the flexibility of the insulator (20) decreases, resulting in poor adhesion between the insulator (20) and the inner conductor (10), and reduced workability or occurrence of cracks during transverse winding. That is, if the outer diameter of the insulator core (21) made of an inflexible material embedded within the flexible refractory layer (23) constituting the insulator (20) is too large, the structural stability of the coaxial structure in which the insulator (20) is interposed is reduced, a large force is required during transverse winding, and the insulator (20) may be damaged during the transverse winding process.

[0090] In addition, the insulating core (21) may include an insulating material having higher refractory performance than the refractory layer (23), so that the temperature at which shape deformation occurs in a high-temperature environment may be higher. For example, even when the refractory layer (23) is deformed in an extreme situation of 1000°C or higher, the insulating core (21) may be configured to space the inner conductor (10) and the outer conductor (30) so that the refractory coaxial cable maintains its function as a cable.

[0091] In this way, the insulator (20) constituting the fire-resistant coaxial cable (100) according to the present invention is configured to include an insulating core (21) and a fire-resistant layer (23) made of a fire-resistant composition that surrounds the insulating core (21), thereby ensuring excellent fire-resistant performance at high temperatures of 750°C or higher, which is the test temperature of standards IEC 60331-11 and IEC 60331-23, while maintaining the internal structure between the inner and outer conductors by the insulator (20).

[0092] The above outer conductor (30) forms a coaxial structure with the inner conductor (10) and is provided spaced apart from the inner conductor (10).

[0093] In this way, the fire-resistant coaxial cable (100) according to the present invention is formed in a coaxial structure in which the inner conductor (10) and the outer conductor (30) have the same central axis.

[0094] Typically, coaxial cables generally use a flexible and thin metal material as the outer conductor (30), but the outer conductor (30) constituting the fire-resistant coaxial cable (100) according to the present invention may be composed of a metal material having excellent rigidity in order to maintain a gap with the inner conductor (10) to secure electrical characteristics, and preferably, the outer conductor (30) may be composed of copper or a copper alloy material, like the inner conductor (10).

[0095] In addition, the external conductor (30) is formed as a corrugation structure in which wrinkles and wrinkle valleys are repeatedly formed, and the flexibility and rigidity of the external conductor (30) can be reinforced by the corrugation structure.

[0096] In addition, the thickness of the outer conductor (30) may be configured in the range of 0.14 millimeters (mm) to 0.45 millimeters (mm). If the thickness of the outer conductor (30) is less than 0.14 millimeters (mm), the rigidity is insufficient, so that the gap between the inner conductor (10) and the outer conductor (30) cannot be maintained well, whereas if the thickness is greater than 0.45 millimeters (mm), the bending characteristics are deteriorated, so that the outer conductor (30) can easily be damaged by cable bending or bending.

[0097] The outer side of the above outer conductor (30) may be covered with a cable jacket (40). The cable jacket (40) may be made of polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyethylene (PE), etc. as a base resin, and may be composed of an insulating composition in which a refractory filler is added to the base resin, if necessary.

[0098] Figure 5 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0099] As illustrated in FIG. 5, another embodiment of a fire-resistant coaxial cable (100) according to the present invention is configured to include an inner conductor (10), an insulator (20) including an insulating core (21) and a fire-resistant layer (23), an outer conductor (30), and a cable jacket (40), similar to the embodiment illustrated in FIG. 4, but the fire-resistant coaxial cable (100) may further include a low-dielectric constant layer (50) wrapping around the outer circumference of the insulator (20). A detailed description of the inner conductor (10), the insulator (20), the outer conductor (30), and the cable jacket (40) constituting the fire-resistant coaxial cable (100) of the present invention in the embodiment illustrated in FIG. 5 overlaps with the description referring to FIG. 4, and thus will be omitted.

[0100] The fire-resistant coaxial cable (100) according to the present invention may additionally include a low-dielectric layer (50) that wraps the outer surface of the insulator (20) in the longitudinal direction. The low-dielectric layer (50) may be configured to reduce the dielectric constant of the coaxial cable.

[0101] The low-k dielectric layer (50) may be composed of a layer having a dielectric constant of 2.5 or less. The low-k dielectric layer (50) may be composed of one or a combination of at least two or more low-k materials selected from the group consisting of polyethylene (PE), high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), and fluorinated ethylene propylene (FEP). In addition, the low-k dielectric material may be coated on the outside of the insulator (20).

[0102] When the fire-resistant coaxial cable (100) according to the present invention further includes a low-dielectric constant layer (50) that wraps around the outer surface of the insulator (20), the fiber yarn constituting the insulating core (21) of the insulator (20) may include glass yarn, and the fire-resistant layer (23) of the insulator (20) may include fire-resistant silicone rubber.

[0103] In this way, by coating a low-dielectric constant material on the outside of the insulator (20) to add a low-dielectric constant layer (50) and winding the insulator (20) transversely on the outside of the inner conductor (10) in a preset pitch range to form an insulating structure between the inner conductor (10) and the outer conductor (30), the fire resistance performance can be maintained while reducing the dielectric constant, and the original communication performance of the coaxial cable can be improved through this reduction in the dielectric constant.

[0104] Additionally, an insulating refractory reinforcing layer (not shown) having high fire resistance characteristics may be further provided that wraps the outer side of the insulator (20) in the longitudinal direction on the outer side of the low-dielectric constant layer (50) or on the inner side of the low-dielectric constant layer (50). In addition, since the insulating refractory reinforcing layer wraps the outer side of the insulator (20), it can block mutual contact between the inner conductor (10) and the outer conductor (30), thereby reinforcing the insulation function between the inner conductor (10) and the outer conductor (30).

[0105] The above-mentioned insulating refractory reinforcement layer may be composed of one or at least two or more highly refractory insulating materials selected from the group consisting of basalt fiber, mica tape, silica fiber, ceramic fiber, and glass fiber.

[0106] The basalt fiber constituting the above-mentioned insulating refractory reinforcing layer can be manufactured by melting basalt powder made of basalt at 1,500°C and spinning it into filaments of 9 μm to 20 μm in size using centrifugal force.

[0107]

[0108] The chemical composition of basalt is high in Cao, MgO, and FeO+Fe2O3, and the SiO2 content is less than 52%. Due to this chemical composition, basalt has excellent chemical stability and has excellent heat resistance at high temperatures.

[0109] The basalt fibers constituting the above-mentioned insulating refractory reinforcing layer may be configured in the form of braided basalt fibers or may be configured in the form of coating the basalt fibers by applying a coating material such as carbon-based, silicone-based or urethane-based.

[0110] The mica tape constituting the above-mentioned insulating refractory reinforcing layer can be manufactured in the form of a tape by bonding white mica (soft mica, hard mica) powder obtained from the natural mineral muscovite onto a PE film or glass fiber fabric. The number of turns of the mica tape can be varied depending on the required refractory performance, cable structure, and intended use.

[0111] The glass fibers constituting the above insulating refractory reinforcing layer can be either long fibers wound by high-speed drawing out molten glass or short fibers manufactured into a plane by blowing molten glass using a centrifugal force method or a flame method.

[0112] Here, the glass fibers constituting the insulating refractory reinforcement layer may be provided in the form of a glass tape by bonding glass fibers coated with silicone adhesive or acrylic adhesive, etc., to a polymer substrate. In addition, the glass fibers constituting the insulating refractory reinforcement layer may be provided in the form of horizontally winding glass fibers on the outer surface of the refractory layer (23) and coating the glass yarns using a non-metallic or metallic coating material.

[0113] The fire-resistant coaxial cable (100) according to the present invention may further reinforce the fire resistance and insulation functions through the insulator by further providing an insulating fire-resistant reinforcing layer on the outside of the insulator (20) or the outside of the low-dielectric constant layer (50). For example, the fire-resistant coaxial cable (100) according to the present invention may maintain the cable function for a certain period of time even at high temperatures of 1000°C or higher.

[0114] In addition, the insulating refractory reinforcement layer that wraps around the outside of the insulator (20) may include an insulating material with higher refractory performance than the refractory layer (23), so that the temperature at which shape deformation occurs in a high-temperature environment may be higher. For example, even when the refractory layer (23) is deformed in an extreme situation of 1000°C or higher, the insulating refractory reinforcement layer may be configured to separate the inner conductor (10) and the outer conductor (30) so that the cable can maintain its communication function.

[0115] In order to verify the performance of the insulation of the fire-resistant coaxial cable configured as described above, coaxial cables were manufactured by configuring the insulation of Examples 1 to 3 and Comparative Examples 1 to 3 with various materials, and a pulling force test was performed to measure the transverse winding workability of the insulation on the outside of the inner conductor, the adhesion of the insulation, a fire resistance test to verify the fire resistance performance, and a test to measure the attenuation according to the spiral insulation structure and the material of the insulation. Here, the outer diameter of the inner conductor of Examples 1 to 3 and Comparative Examples 1 to 3 was 3.6 mm, the outer diameter of the insulation was 3.1 mm, and the transverse winding pitch of the insulation was 25 mm for the tests. The results in Table 1 below are the results of the above tests of Examples 1 to 3 and Comparative Examples 1 to 3.

[0116] [Table 1]

[0117]

[0118] Specifically, Example 1 is an example in which an insulating core (21) constituting an insulator (20) is composed of glass yarn and a fire-resistant layer (23) includes silicone rubber and a low-dielectric layer (50) is provided that wraps the outside of the insulator (20), and the material of the low-dielectric layer (50) is an HDPE coating, Example 2 is an example in which an insulating core (21) constituting an insulator (20) is composed of glass yarn and a fire-resistant layer (23) includes silicone rubber, Example 3 is an example in which an insulating core (21) constituting an insulator (20) is composed of glass yarn and a fire-resistant layer (23) includes fluorine rubber, Comparative Example 1 is a comparative example in which the entire insulator (20) is composed of basalt, Comparative Example 2 is a comparative example in which the entire insulator (20) is composed of polyethylene (PE) material, and Comparative Example 3 is an example in which an insulating core (21) constituting an insulator (20) is composed of silica and a fire-resistant layer (23) is ceramic. This is a comparative example including a refractory layer.

[0119] The evaluation of the transverse winding workability of the insulation around the inner conductor was performed by visually assessing the extent to which the insulation was broken or damaged on the surface when the insulation was transversely wound around the inner conductor, and categorizing the results as good or poor. In the case of poor transverse winding workability, the insulator wound around the inner conductor cannot stably maintain the separation structure between the inner and outer conductors.

[0120] In Examples 1 to 3, in which the refractory layer (23) constituting the insulator comprises silicone rubber or fluoro rubber, and in Comparative Example 2, in which the insulator comprises polyethylene (PE), the lateral winding workability was good because the insulator was not damaged during lateral winding due to the flexibility of the material. However, in Comparative Examples 1 and 3, in which the insulator was comprised of a basalt or ceramic refractory layer that was not flexible and hard, the lateral winding workability was poor because the insulator was broken and the surface was destroyed when the insulator was lateral wound on the outside of the inner conductor.

[0121] In addition, in the pulling force test for measuring the adhesion of the above-mentioned insulator (20), if the maximum pulling force is less than 2 kgf, the outer conductor and the inner conductor are easily separated with a small force, so that structural damage between the inner conductor and the outer conductor can easily occur due to the external tensile force, and it is difficult to ensure the reliability of the cable during installation and use, as described above.

[0122] Examples 1 to 3 and Comparative Example 2, which have flexible insulators, have excellent transverse winding workability as well as insulator adhesion, and have a maximum load (Max Pulling Force) of 2 kgf or more, whereas Comparative Examples 1 and 3, which have inflexible insulators and are made of hard materials, have poor transverse winding workability and, as a result, cannot be adhered to the inner conductor and the outer conductor, and thus, the maximum load (Max Pulling Force) is also low at less than 2 kgf, and thus cannot pass the pulling force test.

[0123] Figure 6 shows the pulling force test results for the specimens of Examples 1 to 3 and Comparative Examples 1 to 3.

[0124] As described above, the pulling force test prepares a 500 mm long fire-resistant coaxial cable specimen, fixes the outer conductor, pulls the inner conductor in the axial direction of the inner conductor at a speed of 50.0 mm / min, measures the elongation (mm) of the inner conductor and the load at that time, and measures the load at the moment when the load reaches its maximum as the maximum load (Max Pulling Force).

[0125] As shown in Fig. 6, in the case of Examples 1 to 3 and Comparative Example 2, the maximum load (Max Pulling Force) was 16.2 kgf, 20.7 kgf, 7.1 kgf and 4.9 kgf, respectively, satisfying the passing standard of 2 kgf or more for the Pulling Force Test. However, in the case of Comparative Examples 1 and 3, the maximum load was 1.4 kgf and 1.0 kgf, respectively, failing the Pulling Force Test, confirming that the adhesiveness of the insulator is poor.

[0126] The fire resistance test is conducted by applying the aforementioned international standard fire resistance standards IEC 60331-11 and IEC60331-23, installing a coaxial cable specimen (length: 1,200 mm) horizontally on the ground on a support, removing about 100 mm of the jacket at both ends of the specimen, connecting it to a voltage application device while ensuring that the inner and outer conductors do not come into contact with each other, and positioning the center of the burner that applies the flame 70±10 mm below the bottom of the specimen, and ensuring that the front of the burner and the central vertical plane of the specimen are separated by 45 mm, applying a flame of 750℃ for 90 minutes. The voltage must be maintained during the flame application, the inner and outer conductors must not be short-circuited, and the conductors must not be ruptured or disconnected.

[0127] Examples 1 to 3 and Comparative Examples 1 and 3, in which a refractory material was applied as the above-mentioned insulator, passed the fire resistance test, but Comparative Example 2, in which a material with a low melting point was used, failed the fire resistance test.

[0128] Attenuation measurements were conducted to determine the attenuation depending on the spiral insulation structure and insulation material. These measurements were conducted by measuring the attenuation resulting from the transmission of a 450 MHz test signal. A lower attenuation indicates better communication cable performance.

[0129] In particular, excellent communication performance can be guaranteed when the attenuation is less than at least 16 (dB / 100m) based on the 450MHz test signal. As a result of the test, the attenuations of Examples 1 to 3 and Comparative Example 2 were measured to be 10.9 (dB / 100m), 13.87 (dB / 100m), 15.29 (dB / 100m), and 9.18 (dB / 100m), respectively, which were lower than the passing standard of 16 (dB / 100m), and thus excellent communication performance could be guaranteed. However, the attenuations of Comparative Examples 1 and 3 were measured to be relatively high at 18.3 (dB / 100m) and 16.6 (dB / 100m), and did not satisfy the condition of less than 16 (dB / 100m), which is the test standard. It is believed that this is because the insulator is composed of a material with a high dielectric constant.

[0130] Accordingly, summarizing the results in Table 1, it is judged that Examples 1 to 3 satisfy the fire resistance performance of the insulator in case of fire, while also ensuring good transverse workability of the insulator and satisfying the condition that the maximum load (Max Pulling Force) in the pulling force test is 2 kgf or more, thereby ensuring adhesion between the insulator and the conductor, and thus the structure of the fire-resistant coaxial cable including the insulator can be stably maintained.

[0131] In particular, it can be confirmed that Examples 1 and 2, which use silicone rubber as the main material of the insulator, can perform communication functions more advantageously due to low attenuation. In particular, Example 1 has the characteristic of performing fire resistance while having low attenuation due to the low dielectric constant between the inner and outer conductors caused by the HDPE coating, which is a low dielectric constant layer, being applied to the outer side of the insulator.

[0132] Figure 7 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0133] As illustrated in FIG. 7, another embodiment of a fire-resistant coaxial cable (100) according to the present invention is configured to include an inner conductor (10), an insulator (20) including an insulating core (21) and a fire-resistant layer (23), an outer conductor (30), a cable jacket (40), a low-dielectric constant layer (50), and an insulating fire-resistant reinforcement layer, similar to the embodiment illustrated in FIG. 5, but may further include a fire-resistant tape layer (60) wrapping around the outer circumference of the outer conductor (30) to reinforce the fire-resistant performance of the fire-resistant coaxial cable (100).

[0134] In the embodiment illustrated in Fig. 7, any duplicate content with reference to Figs. 4 and 5 will be omitted.

[0135] The fire-resistant coaxial cable (100) according to the present invention may be provided with a fire-resistant tape layer (60) having high fire-resistant properties that wraps the outer side of the outer conductor (30) in the longitudinal direction.

[0136] The above-mentioned refractory tape layer (60) may be composed of one or more highly refractory materials, such as a mica tape, a glass tape, and a metal tape. In this way, the refractory tape layer (60) may be composed of a tape member to secure flexibility and bending characteristics of the refractory coaxial cable (100).

[0137] The description of the mica tape or glass tape constituting the above refractory tape layer (60) is the same as that described in the insulating refractory reinforcement layer.

[0138] The metal tape constituting the above refractory tape layer (60) may be made of a refractory metal material such as copper, aluminum, iron, copper alloy, or aluminum alloy.

[0139] As shown in FIG. 7, when the fire-resistant coaxial cable (100) according to the present invention has the fire-resistant tape layer (60), not only the insulator (20) and the insulating fire-resistant reinforcement layer, but also the fire-resistant tape layer (60) additionally performs a fire-resistant function, so that the fire-resistant coaxial cable (100) according to the present invention has excellent fire resistance even at high temperatures of 1000°C or higher, and can maintain the cable function for a certain period of time.

[0140] Figure 8 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0141] As illustrated in FIG. 8, another embodiment of a fire-resistant coaxial cable (100) according to the present invention is configured to include, similarly to the embodiment illustrated in FIG. 7, an inner conductor (10), an insulator (20) including an insulating core (21) and a fire-resistant layer (23), an outer conductor (30), a cable jacket (40), a low-dielectric constant layer (50), an insulating fire-resistant reinforcement layer, and a fire-resistant tape layer (60). However, the fire-resistant coaxial cable (100) may further include a conductor fire-resistant reinforcement layer (70) that wraps around the outer circumference of the inner conductor (10) to further improve fire-resistant performance.

[0142] In the embodiment illustrated in Fig. 8, any duplicate descriptions with reference to Figs. 4, 5, and 7 will be omitted.

[0143] The fire-resistant coaxial cable (100) according to the present invention may be provided with a conductor fire-resistant reinforcement layer (70) having high fire-resistant properties that wraps around the outer surface of the inner conductor (10) arranged in the center in the longitudinal direction.

[0144] The conductor refractory reinforcement layer (70) may be formed by combining one or at least two or more highly refractory insulating materials, such as basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape, similar to the insulating refractory reinforcement layer. Each refractory material of the conductor refractory reinforcement layer (70) is as described in the insulating refractory reinforcement layer.

[0145] As shown in FIG. 8, when the fire-resistant coaxial cable (100) according to the present invention has a conductor fire-resistant reinforcement layer (70), the conductor fire-resistant reinforcement layer (70) as well as the insulator (20), the insulation fire-resistant reinforcement layer and the fire-resistant tape layer (60) additionally perform a fire-resistant function, so that the fire-resistant coaxial cable (100) according to the present invention has excellent fire resistance even at high temperatures of 1000°C or higher and can maintain the fire-resistant coaxial cable function for a certain period of time.

[0146] Furthermore, the conductor refractory reinforcement layer (70) can reinforce the insulation function of the inner conductor (10) by preventing a short circuit caused by mutual contact between the inner conductor (10) and the outer conductor (30) in addition to further improving the refractory performance of the cable.

[0147] The conductor refractory reinforcement layer (70) may include an insulating material having higher refractory performance than the refractory layer (23), and thus the temperature at which shape deformation occurs in a high-temperature environment may be higher. For example, even when the refractory layer (23) is deformed in an extreme situation of 1000°C or higher, the conductor refractory reinforcement layer (70) may be configured to space the inner conductor (10) and the outer conductor (30) so that the refractory coaxial cable (100) can maintain its cable function for a certain period of time.

[0148] Here, the fire-resistant coaxial cable (100) according to the present invention is presented as including all of a low-dielectric layer (50), an insulating fire-resistant reinforcement layer, a fire-resistant tape layer (60), and a conductor fire-resistant reinforcement layer (70), but in addition, it may be configured to include one or at least two or more of the low-dielectric layer (50), the insulating fire-resistant reinforcement layer, the fire-resistant tape layer (60), and the conductor fire-resistant reinforcement layer (70).

[0149] Figure 9 illustrates a cross-sectional view of another embodiment of a fire-resistant coaxial cable according to the present invention.

[0150] As illustrated in FIG. 9, the fire-resistant coaxial cable (100) according to the present invention is configured to include an inner conductor (10), an insulator (20) including an insulating core (21') inside and a fire-resistant layer (23') outside, an outer conductor (30), and a cable jacket (40), similar to the embodiment illustrated in FIG. 4. However, in the embodiment illustrated in FIG. 9, the insulator (20) may be configured to include a material other than glass yarn as the material of the insulating core (21') and a fire-resistant material other than fire-resistant silicone rubber as the material of the fire-resistant layer (23').

[0151] Specifically, the insulating core (21') of the insulator (20) includes flexible polyethylene having a low dielectric constant, and the refractory layer (23') of the insulator (20) can be formed by combining one or at least two high-refractory insulating materials selected from among basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape. Accordingly, an insulator (20) that can maintain refractory performance while implementing a low dielectric constant and flexibility can be formed.

[0152] When the above refractory layer (23') includes basalt fibers, the basalt fibers may be configured in a braided or coated form.

[0153] When the above refractory layer (23') includes glass fiber, it may be configured in the form of a tape or coated form of glass fiber.

[0154] The above-mentioned refractory layer (23') may be composed of a refractory material having high refractory properties that wraps the outer surface of the insulating core (21') in the longitudinal direction. The above-mentioned insulator (20) has a refractory layer (23') composed of one or at least two or more refractory insulating materials selected from among basalt fiber, mica tape, and glass fiber, so that even if the insulating core (21') having a relatively low melting point completely burns or melts at a high temperature, the refractory layer (23') arranged on the outside of the insulating core (21') can remain and perform its refractory function.

[0155] Here, the fire-resistant coaxial cable according to the present invention may omit the low-dielectric constant layer (50) (see FIGS. 5, 7, and 8) or the insulation refractory reinforcement layer provided on the outside of the insulator (20). This is because the insulating core (21') of the insulator (20) already contains polyethylene and thus can have a sufficiently low dielectric constant, and the refractory layer (23') is already composed of a refractory material such as basalt fiber, mica tape, or glass fiber. In addition, the fire-resistant coaxial cable (100) according to the present invention applies a high refractory material to the refractory layer (23') of the insulator (20), as illustrated in FIG. 9, and further includes at least one of a refractory tape layer (60) wrapping the outer conductor (30) or a conductor refractory reinforcement layer (70) wrapping the inner conductor (10), thereby ensuring excellent fire resistance even at high temperatures of 1000°C or higher, thereby allowing the cable to maintain its function for a certain period of time.

[0156] The fire-resistant coaxial cable (100) according to the present invention can be applied to various environments such as specific fire-fighting objects requiring installation of wireless communication auxiliary equipment, other buildings, road tunnels, hazardous material storage and processing facilities, and underground facilities.

[0157]

[0158] [Examples according to the structure of the insulator]

[0159]

[0160] 1. Manufacturing example

[0161]

[0162] Coaxial cable specimens were manufactured according to the design described in Table 2 below. Examples 4 to 7 and Comparative Examples 4 to 6 follow the structure of Fig. 4, with the inner conductor and outer conductor made of copper and the insulator made of silicone rubber and glass yarn as the refractory layer and the insulating core, respectively.

[0163]

[0164] [Table 2]

[0165]

[0166]

[0167] 2. Physical property evaluation

[0168]

[0169] 1) Fire resistance evaluation

[0170] Each of the coaxial cable specimens (length: 1,200 mm) of Examples 4 to 7 and Comparative Examples 4 to 6 is installed horizontally on the ground on a support, and the jacket at both ends of the specimen is peeled off by about 100 mm. Then, the inner conductor and the outer conductor are connected to a voltage application device so that they do not come into contact with each other. The center of the burner that applies the flame is positioned 70±10 mm below the bottom of the specimen, and the front of the burner and the central vertical plane of the specimen are separated by 45 mm. A flame of 750°C is applied for 90 minutes. The voltage must be maintained during the flame application and the conductor must not be ruptured or disconnected.

[0171]

[0172] 2) Characteristic impedance evaluation

[0173] For each of the coaxial cable specimens (length: 100 m) of Examples 4 to 7 and Comparative Examples 4 to 6, the characteristic impedance was measured by measuring the average value of the corresponding frequency in the frequency band of 30 to 1000 MHz using a measuring instrument (Network Analyzer), and it should be 45 to 55 Ω.

[0174]

[0175] 3) Flexibility evaluation

[0176] Each of the coaxial cable specimens of Examples 4 to 7 and Comparative Examples 4 to 6 was wound once on a circular mandrel with a diameter of 120 mm when the corrugation shape of the coaxial cable was spiral, and once on a circular mandrel with a diameter of 280 mm when the corrugation shape of the coaxial cable was annular, and the sensory workability of the operator was evaluated. If excessive force was required when winding once compared to a cable of similar size, it was evaluated as defective.

[0177]

[0178] 4) Structural stability (short) evaluation

[0179] Each of the coaxial cable specimens of Examples 4 to 7 and Comparative Examples 4 to 6 was wound once on a circular mandrel with a diameter of 120 mm when the corrugation shape of the coaxial cable was spiral, and once on a circular mandrel with a diameter of 280 mm when the corrugation shape of the coaxial cable was annular. A multimeter was connected to the inner conductor and the outer conductor to evaluate whether the inner conductor and the outer conductor were in contact, and if they were in contact, it was evaluated as a failure.

[0180]

[0181] The results of the above property evaluation are as described in Table 3 below.

[0182]

[0183] [Table 3]

[0184]

[0185] As described in Table 3 above, the coaxial cable specimens of Examples 4 to 7, in which the inclination angle and outer diameter of the insulator were precisely designed during transverse winding, were confirmed to have excellent fire resistance, characteristic impedance, flexibility, structural stability, etc.

[0186] Meanwhile, the coaxial cable specimen of Comparative Example 4 was found to have a short circuit due to contact between the inner conductor and the outer conductor during bending due to the inclination angle standard being below the standard during transverse winding of the insulator; the coaxial cable specimen of Comparative Example 5 had a characteristic impedance exceeding the standard, a bendability deteriorating, and a manufacturing cost increasing due to the inclination angle standard being above the standard during transverse winding of the insulator; and the coaxial cable specimen of Comparative Example 6 had a characteristic impedance deteriorating due to insufficient gap between the inner conductor and the outer conductor as the outer diameter of the insulator was below the standard.

[0187] While this specification has described preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention as defined in the claims below. Therefore, any modified implementation that fundamentally includes the elements of the claims should be considered within the technical scope of the present invention.

Claims

1. Internal conductor placed in the center; An insulator wound transversely on the outside of the inner conductor; An outer conductor that surrounds the outer side of the insulator and forms a coaxial structure with the inner conductor; and A cable jacket covering the outside of the outer conductor; The above insulator has an insulating core and a refractory layer surrounding the insulating core, A fire-resistant coaxial cable characterized in that the fire-resistant layer comprises silicone rubber.

2. Internal conductor placed in the center; An insulator wound transversely on the outside of the inner conductor; An outer conductor that surrounds the outer side of the insulator and forms a coaxial structure with the inner conductor; and A cable jacket covering the outside of the outer conductor; The above insulator has an insulating core and a refractory layer surrounding the insulating core, A fire-resistant coaxial cable, characterized in that the fire-resistant layer comprises a fire-resistant elastomer.

3. Internal conductor placed in the center; An insulator wound transversely on the outside of the inner conductor; An outer conductor that surrounds the outer side of the insulator and forms a coaxial structure with the inner conductor; and A cable jacket covering the outside of the outer conductor; The above insulator has an insulating core and a refractory layer surrounding the insulating core, The insulating core of the above insulator comprises polyethylene, A fire-resistant coaxial cable characterized in that the fire-resistant layer of the above insulation comprises at least one of basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape.

4. In paragraph 2, A fire-resistant coaxial cable characterized in that the fire-resistant layer of the above insulation comprises silicone rubber.

5. In paragraph 1 or 2, A fire-resistant coaxial cable characterized in that the insulating core of the above insulator includes a tensile member.

6. In paragraph 5, A fire-resistant coaxial cable characterized in that the tensile strength of the insulating core including the above tensile member is 5 g / TEX or more.

7. In paragraph 5, A fire-resistant coaxial cable, characterized in that the above tensile member comprises at least one of basalt fiber, glass fiber, silica fiber, ceramic fiber, or aramid fiber materials.

8. In paragraph 7, A fire-resistant coaxial cable characterized in that the above tensile member includes glass yarn.

9. In paragraph 1 or 2, A fire-resistant coaxial cable characterized in that the temperature at which the above insulating core undergoes shape deformation at a higher temperature than the above refractory layer.

10. In paragraph 1 or 2, A fire-resistant coaxial cable characterized in that the maximum load applied when the outer conductor of the fire-resistant coaxial cable having a length of 500 mm is fixed and the inner conductor is pulled in the axial direction of the inner conductor at a speed of 50.0 mm / min is 2 kgf or more.

11. In paragraph 1 or 2, A fire-resistant coaxial cable characterized by including a low-dielectric constant layer having a dielectric constant of 2.5 or less, which surrounds the above-mentioned insulator.

12. In paragraph 11, A fire-resistant coaxial cable characterized in that the low-dielectric constant layer comprises at least one of PE (Polyethylene), HDPE (High-Density Polyethylene), PTFE (Polytetrafluoroethylene), and FEP (Fluorinated ethylene propylene).

13. In paragraph 1 or 2, A fire-resistant coaxial cable characterized by including an insulating refractory reinforcing layer that surrounds the insulator and reinforces the fire-resistant performance of the fire-resistant coaxial cable.

14. In paragraph 13, A fire-resistant coaxial cable, characterized in that the above-mentioned insulating refractory reinforcement layer comprises at least one of basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape.

15. In any one of paragraphs 1 to 3, A fire-resistant coaxial cable characterized in that it further includes one or more fire-resistant tape layers wrapping the outer side of the outer conductor to enhance the fire-resistant performance of the fire-resistant coaxial cable.

16. In paragraph 15, A fire-resistant coaxial cable, characterized in that the fire-resistant tape layer comprises at least one of a mica tape, a glass tape, and a metal tape.

17. In any one of paragraphs 1 to 3, A fire-resistant coaxial cable characterized in that it further includes a conductor fire-resistant reinforcement layer surrounding the inner conductor to enhance the fire-resistant performance of the fire-resistant coaxial cable.

18. In paragraph 17, A fire-resistant coaxial cable characterized in that the conductor refractory reinforcement layer comprises at least one of basalt fiber, silica fiber, ceramic fiber, glass fiber, and mica tape.

19. In any one of paragraphs 1 to 3, A fire-resistant coaxial cable characterized in that the inner conductor and the outer conductor are made of copper or a copper alloy material.

20. In any one of paragraphs 1 to 3, A fire-resistant coaxial cable characterized in that the outer conductor has a corrugated pipe structure in which corrugated mountains and corrugated valleys are repeatedly formed.

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