A high flame retardant cable

Abstract

The application relates to the cable technical field, and aims to provide a high-flame-retardant cable which comprises a cable core and a plurality of flame-retardant mechanisms arranged at the outer side of the cable core in the length direction and spaced apart, and a filling strip arranged between adjacent flame-retardant mechanisms; the flame-retardant mechanisms and the filling strip are wrapped at the outer side of the cable core through a binding belt, and an outer sheath layer is arranged outside the binding belt; an elastic opening component is arranged between two adjacent flame-retardant strips, and the elastic opening component can be accommodated between the flame-retardant strips before a pressing ring is burnt off; after the pressing ring is burnt off, the elastic opening component can be opened along with the lifting action of the flame-retardant strips and continuously apply a pushing force to the flame-retardant strips; and the elastic opening component can partially fill the space between the adjacent flame-retardant strips after the flame-retardant strips are completely lifted. After the sheath layer and the binding belt of the cable are burnt, the flame-retardant strips of the flame-retardant mechanisms can be lifted more quickly and stably under the assistance of the elastic opening component, a flame-retardant disc is formed, the response speed is improved, and the spread of the ignition point along the length direction of the cable is avoided.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and more specifically to a high flame-retardant cable. Background Technology

[0002] Flame-retardant cables are cables that, under specified test conditions, when burned and the fire source removed, exhibit flames that only spread within a limited area and self-extinguish. Their characteristic is to delay the spread of flames along the cable, preventing the fire from escalating. They typically use flame-retardant materials as insulation and sheathing layers, and some also incorporate flame-retardant fillers or wrapping with flame-retardant tape in the cable structure. Compared to ordinary cables, flame-retardant cables effectively suppress flame propagation during a fire, reducing the generation of smoke and toxic gases, thus buying more time for evacuation and firefighting. Traditional flame-retardant cables primarily improve their flame retardancy by modifying the materials used in their filler and flame-retardant layers; however, this approach is time-consuming to develop and limited by the inherent properties of various materials, resulting in less than ideal development progress.

[0003] To address this, some technicians have improved the overall flame-retardant properties of cables by modifying their physical structure to physically isolate the combustion point. For example, Chinese invention patent CN119274867A describes a low-smoke halogen-free flame-retardant cable. This cable incorporates a functional protective component, including a ring and several elastic plates on the ring. The elastic plates are pressed against the ring by rubber rings. When the outer sheath and binding tape of the cable are partially burned through, the rubber rings break, and the elastic plates of the functional protective component can lift up under their own elasticity. These lifting plates form a disc-shaped fire-retardant disc on the cable's circumference. This flame-retardant disc absorbs high temperatures and isolates the spread of fire, preventing the combustion point from extending along the cable's length. While this cable significantly improves its flame-retardant performance through the special design of its functional protective component, it still has the following drawbacks:

[0004] like Figure 1 (As shown in the simplified diagram of the cable above), the length of the elastic plate is limited, allowing only small-sized fire-retardant discs to be constructed. As the length of the elastic plate increases, the gap between the elastic plates increases with the distance from the cable axis. Figure 1The larger the 0) value, the less filler it contains, making effective fire isolation impossible. A more critical drawback is that after the rubber ring burns out, the cable relies entirely on the elasticity of the elastic plate (connected to the ring) to spring back. Since the outer sheath and binding tape often leave residue after burning, this residue hinders the elasticity of the plate, making its flame-retardant response time longer and worse. To ensure rapid and stable spring-back, it's necessary to improve the elastic plate material to increase its elasticity or increase its thickness. Material improvement is not a quick process. Increasing the thickness increases the outer diameter in certain areas (where the ring and elastic plate are installed). To maintain the overall shape consistency and fullness of the cable along its length, the difficulty of covering the outer layer materials (outer sheath, binding tape, etc.) increases significantly, or more filler is needed. All of these factors hinder the practical application of this low-smoke halogen-free flame-retardant cable. Summary of the Invention

[0005] The purpose of this invention is to provide a high flame-retardant cable with fast flame-retardant response.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is: a high flame-retardant cable, comprising a cable core and a plurality of flame-retardant mechanisms spaced apart outside the cable core along the length direction, with filler strips provided between adjacent flame-retardant mechanisms; the flame-retardant mechanisms and filler strips are wrapped around the cable core by a strapping tape, and an outer sheath layer is provided outside the strapping tape;

[0007] The flame-retardant mechanism includes a collar sleeved outside the cable core and several elastic flame-retardant strips disposed on the circumferential surface of the collar. One end of the flame-retardant strip is fixed to the collar, and the other end is pressed against the collar by a pressing ring sleeved outside the collar. When the pressing ring burns out, the flame-retardant strip can be lifted up under elastic action to form a flame-retardant disc on the circumferential surface of the cable core.

[0008] An elastic expansion component is provided between two adjacent flame-retardant strips. Before the pressing ring burns out, the elastic expansion component can be stored between the flame-retardant strips. After the pressing ring burns out, it can open with the lifting action of the flame-retardant strip and continuously apply a pushing force to the flame-retardant strip. Moreover, the elastic expansion component can partially fill the space between adjacent flame-retardant strips after the flame-retardant strip is fully lifted.

[0009] Preferably, the elastic support component includes a metal spring sheet, which is bent into a U-shape and secured between the flame-retardant strips, with both ends of the metal spring sheet being movably connected to the sidewalls of the flame-retardant strips.

[0010] Preferably, the metal spring is provided with spherical shells at both ends, and the flame-retardant strip is provided with a ball head on its side wall. The metal spring is hinged to the flame-retardant strip by being secured to the ball head through the spherical shells.

[0011] Preferably, each set of the elastic support components includes multiple metal springs, which are arranged along the length of the flame-retardant strip, and the U-shaped bending is successively fitted along the length of the flame-retardant strip.

[0012] Preferably, the flame-retardant strip is a stamped part, and stepped mounting grooves are stamped on both sides of the flame-retardant strip, with the ball head on the flame-retardant strip disposed in the mounting groove.

[0013] Preferably, the surface of the flame-retardant strip opposite to the pressing ring is stamped with an end groove for the pressing ring to be inserted, and the end groove is located close to the two ends of the longest metal spring; the center of the metal spring is provided with a protrusion, and in the stored state, the middle of each metal spring is pressed by the protrusion on the adjacent metal spring.

[0014] Preferably, the cable core includes at least three wire cores, which are evenly distributed in a ring around the center of the cable core; each wire core includes a conductive core material, and an insulation layer, a shielding layer, and an inner sheath layer sequentially sleeved on the conductive core material from the inside out; the area of ​​the cable core outside the wire cores constitutes a filling area.

[0015] Preferably, a rubber support frame is provided in the middle of the cable core along the length of the cable core, and a plurality of support grooves corresponding to the number of wire cores are evenly distributed in a ring on the rubber support frame; the wire cores are located in the support grooves.

[0016] Preferably, the rubber support frame has a central hole extending along the length of the rubber support frame in the middle, and thermal expansion filler is disposed in the central hole; an expansion port communicating with the support groove is disposed on the hole wall opposite to the central hole and the support groove.

[0017] Preferably, a pad is provided between the bottom of the wire core and the bottom of the support groove, the width of the pad is adapted to the support groove, and the surface of the pad is provided with an arc-shaped surface adapted to the curvature of the wire core surface; flame-retardant filler is provided in the area between adjacent support grooves and in the area of ​​the support groove near the surface of the cable core.

[0018] The beneficial effects of this invention are mainly reflected in the following: after the cable sheath and binding tape are burned, the flame-retardant strip of the flame-retardant mechanism can be raised more quickly and stably with the assistance of the elastic spreading component to form a flame-retardant disc, thereby improving the response speed and preventing the ignition point from spreading along the length of the cable. Specifically, during use, before the pressing ring is burned off, the flame-retardant strip is completely attached to the surface of the collar, and the elastic spreading component is completely housed between the two flame-retardant strips. At this time, because the flame-retardant strips are tightly arranged, the pushing force of the elastic spreading component on the flame-retardant strip is entirely a lateral pushing force on the flame-retardant strip, and will not be directly superimposed with the elastic force of the flame-retardant strip. This will not excessively increase the reaction force on the pressing ring, and the pressing ring can form a pressing force on the flame-retardant strip without thickening or enlarging, ensuring the thermal sensitivity and responsiveness of the pressing ring after it is burned off. As the pressing ring burns through, the flame-retardant strip begins to curl up under its own elastic force. With this change in position, the thrust from the elastic spreading component increasingly transforms into a thrust that aligns with the curling direction of the strip, combining with its own elasticity to cause it to quickly and stably spring up, forming a flame-retardant disc. This method effectively reduces interference from burning residue on the flame-retardant strip's curl, improving response speed and stability. Furthermore, the linkage between the movements of each flame-retardant strip via the elastic spreading component creates an "organic whole" of elastic transmission, resulting in greater stability in the movement of all the flame-retardant strips. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an existing cable;

[0020] Figure 2 This is a schematic diagram of the structure of the present invention;

[0021] Figure 3 This is a schematic diagram of the flame-retardant mechanism;

[0022] Figure 4 This is a schematic diagram of the structure when the flame-retardant strip of the flame-retardant mechanism is raised.

[0023] Figure 5 This is a schematic diagram of the flame-retardant strip structure;

[0024] Figure 6 This is a schematic diagram of the structure of a metal shrapnel.

[0025] Figure 7 This is a schematic diagram of the cross-sectional structure of the present invention;

[0026] Figure 8 This is a schematic diagram of the rubber support frame. Detailed Implementation

[0027] This invention relates to a highly flame-retardant cable, which achieves mechanical flame retardancy along the longitudinal direction of the cable through a unique shape and structural design, such as... Figure 2 As shown, the cable of the present invention includes a cable core, such as... Figure 7 As shown, the cable core typically comprises at least three conductors 13, which are uniformly distributed in a ring around the center of the cable core. The structure of the conductor 13 itself is similar to that of existing flame-retardant conductors, comprising a conductive core material, and an insulation layer, a shielding layer, and an inner sheath layer sequentially disposed outside the conductive core material from the inside out. The area of ​​the cable core outside the conductors 13 constitutes a filling area, which is filled with filler.

[0028] The present invention also includes a plurality of flame-retardant mechanisms 1 spaced apart along the length of the cable core. These flame-retardant mechanisms 1 serve as the basis for the mechanical isolation and flame retardancy of the present invention. Filler strips are provided between adjacent flame-retardant mechanisms 1, filling the gaps between them and maintaining the overall fullness of the cable. As the outermost layer of the cable, the flame-retardant mechanisms 1 and filler strips are wrapped around the cable core by binding straps 2, with an outer sheath layer 3 provided outside the binding straps 2. The above structure is similar to that of the aforementioned low-smoke halogen-free flame-retardant cable, and some aspects of the structure can be referenced therein.

[0029] From the basic structure of the flame-retardant mechanism 1, this invention also adopts the form of a ring + several barrier plates, such as... Figure 3 and 4 As shown, the flame-retardant mechanism 1 includes a collar 4 sleeved around the cable core and several elastic flame-retardant strips 5 disposed on the circumference of the collar 4. The flame-retardant strips 5 are made of metal. One end of the flame-retardant strip 5 is fixed to the collar 4 (e.g., by snap-fitting, riveting, welding, etc.), and the other end is pressed against the collar 4 by a pressing ring 6 sleeved around the collar 4. When not constrained by the pressing ring 6, the flame-retardant strip 5 can bend up under its own elasticity to such an extent that... Figure 4 The state shown in the diagram. That is, when the pressing ring 6 burns out, the flame-retardant strip 5 can be lifted up under elastic action to form a flame-retardant disc on the circumferential surface of the cable core.

[0030] However, after some verification, we found that because the outer layer of the flame-retardant mechanism 1 is also equipped with a binding strap 2 and an outer sheath layer 3, when an ignition point appears on the cable, the outer layer often does not burn completely, leaving some residue. When the pressing ring 6 burns off, this residue sometimes hinders the normal rebound of the flame-retardant strip 5, causing the flame-retardant response speed to slow down or even fail. Furthermore, when the pressing ring 6 is made of rubber, there is more combustion residue and the melting speed is relatively slow. Therefore, a better approach is to use nylon thread for the pressing ring 6, which has high-temperature sensitivity and can melt quickly, improving the response speed. In addition, based on the original structure, this invention further improves the flame-retardant response speed of the flame-retardant strip 5 by modifying the flame-retardant mechanism 1.

[0031] The most significant difference in this invention is, for example Figure 5As shown, the present invention provides an elastic spreading component between two adjacent flame-retardant strips 5. Before the pressing ring 6 burns out, this elastic spreading component can be housed between the flame-retardant strips 5 without increasing the overall volume of the cable. At this time, since the flame-retardant strips 5 are completely attached to the surface of the collar 4, the elastic spreading component is housed between the two flame-retardant strips 5. The flame-retardant strips 5 are tightly arranged, and the thrust of the elastic spreading component on the flame-retardant strips 5 is entirely a lateral thrust. This thrust has a large vector difference with the elastic force of the flame-retardant strip 5 itself and will not be directly superimposed on the elastic force of the flame-retardant strip 5. Therefore, it will not excessively increase the reaction force on the pressing ring 6, and the pressing ring 6 can press against the flame-retardant strips 5 without needing to be thickened or enlarged, ensuring the thermal sensitivity and responsiveness of the pressing ring 6 after it burns out.

[0032] After the pressing ring 6 burns out, the flame-retardant strip 5, due to its own elasticity, lifts up. The elastic opening component opens in sync with the lifting motion of the flame-retardant strip 5, continuously applying a pushing force to it. As the pressing ring 6 burns out, the flame-retardant strip 5 begins to lift up under its own elasticity. As the position of the flame-retardant strip 5 changes, the pushing force from the elastic opening component increasingly transforms into a pushing force adapted to the lifting direction of the flame-retardant strip 5 (meaning the pushing force from the elastic opening component changes direction with the position of the flame-retardant strip 5), and this force, combined with the elasticity of the flame-retardant strip 5, causes it to quickly and stably lift up, forming a flame-retardant disc. Using this method, with the greater force applied to the flame-retardant strip 5 (its own elasticity + the pushing force from the elastic opening component), the interference of burning residue on the lifting of the flame-retardant strip 5 is effectively reduced, improving response speed and stability. In addition, since there are elastic support components between the flame retardant strips 5, the movement of each flame retardant strip 5 is linked by the elastic support components, forming an "organic whole" with elastic transmission. When a certain flame retardant strip 5 moves, the surrounding adjacent flame retardant strips 5 can also be pulled, thereby making the movement stability of all flame retardant strips 5 higher.

[0033] In addition, as the flame-retardant strips 5 are fully opened, the elastic expansion component of this invention can also act as a filler for the outer gaps 0 between the flame-retardant strips 5. That is to say, the elastic expansion component can partially fill the space between adjacent flame-retardant strips 5 after the flame-retardant strips 5 are fully raised. This significantly improves the flame-retardant effect of the flame-retardant disc and reduces the possibility of fire spreading through gaps. On this basis, if a layer of foldable flexible fireproof cloth is set on one side of the flame-retardant disc, the combination of the flame-retardant strips 5 and the elastic expansion component to form a skeleton, and the flexible fireproof cloth is used for isolation, can be a better choice. Of course, the thickness of the flexible fireproof cloth should not be too thick to prevent the cable cross-section from becoming thicker after being pressed and folded by the flame-retardant strips 5.

[0034] Regarding the elastic expansion component, the specific structural form that can be adopted by the present invention can be combined with... Figure 5 and6 As shown, the elastic expansion assembly includes a metal spring 7, which is bent into a U-shape and secured between the flame-retardant strips 5. Both ends of the metal spring 7 are connected to the sidewalls of the flame-retardant strips 5. The connection is generally a movable link, meaning the metal spring 7 can change its relative position to the flame-retardant strip 5 within a certain range. For example, the end of the metal spring 7 can be rotatably mounted on the sidewall of the flame-retardant strip 5 using a pin or rivet. This allows the metal spring 7 to rotate for easy storage and also allows it to change its relative position to the flame-retardant strip 5 during its movement. However, to ensure that the metal spring 7 can adaptively cooperate with the flame-retardant strip 5 when it opens, the connection node between the metal spring 7 and the flame-retardant strip 5 should have adaptive directional selectivity. For example... Figure 6 As shown, spherical shells 8 are provided at both ends of the metal spring 7, corresponding to, as Figure 5 As shown, a ball head 9 is provided on the side wall of the flame-retardant strip 5, and a metal spring 7 is secured to the ball head 9 through a ball shell 8 to form a universal hinge with the flame-retardant strip 5.

[0035] Considering that a single metal spring 7 can only seal a limited area of ​​gap 0, this invention can provide multiple metal springs 7 between each pair of flame-retardant strips 5. In other words, as... Figure 5 As shown, each set of the elastic expansion components includes multiple metal springs 7, which are arranged along the length of the flame-retardant strip 5, and the U-shaped bending forms are successively nested along the length of the flame-retardant strip 5. The multiple metal springs 7 can not only fill a larger gap 0, further reducing the risk of fire spread, but also provide greater thrust, making the overall response speed of the flame-retardant mechanism 1 faster.

[0036] When multiple metal spring clips 7 are installed, to avoid mutual interference during installation, stepped mounting grooves 10 are formed on both sides of the flame-retardant strip 5 of the present invention, and the ball head 9 on the flame-retardant strip 5 is disposed in the mounting groove 10. In order to facilitate the processing of the flame-retardant strip 5, the flame-retardant strip 5 is usually a stamped part, the mounting groove 10 is formed by stamping, and the ball head is crimped and riveted to the side wall of the mounting groove 10 of the flame-retardant strip 5.

[0037] In normal use, each metal spring 7 is completely housed within the mounting groove 10, not exceeding the surface of the flame-retardant strip 5. At this time, in order for the pressing ring 6 to also apply pressure to the metal spring 7, such as... Figure 5 As shown, the surface of the flame-retardant strip 5 opposite to the pressing ring 6 is stamped with an end groove 11 for the pressing ring 6 to be inserted. The end groove 11 is located near the two ends of the longest metal spring 7. Since it is impossible to have one pressing ring 6 for each metal spring 7, in order to press all the metal spring 7 with one pressing ring 6, as shown... Figure 6As shown, the metal spring 7 of the present invention has a raised strip 12 at its center. Figure 5 As shown, when the metal springs 7 are in the stored state, the middle of each metal spring 7 is pressed by the protrusions 12 on the adjacent metal springs 7.

[0038] In addition, the cable described in this invention also improves its overall strength through a central support, such as... Figure 7 As shown, a rubber support frame 14 is provided in the middle of the cable core along its length. The rubber support frame 14 has a plurality of support grooves 15 evenly distributed in a ring, corresponding to the number of wire cores 13. The wire cores 13 are located within the support grooves 15. The rubber support frame 14 separates and supports each wire core 13, further ensuring the accuracy of the wire core 13's position. Furthermore, the rubber support frame 14 effectively improves the cable's support, preventing damage caused by dragging or pulling during construction. The rubber support frame 14 also has good overall flexibility, will not cause excessive interference with the cable's routing, and offers high flexibility in use.

[0039] Since this invention is frequently used in special scenarios with high fire protection requirements, in order to further improve the overall performance of this invention, it is combined with... Figure 7 and Figure 8 As shown, a central hole 16 extending along the length of the rubber support frame 14 can also be provided in the middle of the rubber support frame 14, and a thermal expansion filler 17 is provided in the central hole 16. An expansion port 18 communicating with the support groove 15 is provided on the hole wall opposite to the support groove 15 of the central hole 16. When a short circuit occurs, the thermal expansion filler 17 in the short circuit area expands due to heat, and expands and supports the wire cores 13 installed in the rubber support frame 14 through the expansion port 18, thereby increasing the spacing between the wire cores 13. Combined with the porous structure formed by the thermal expansion filler 17 after thermal expansion, short circuit isolation is achieved. Moreover, because the cable in the short circuit area has a certain expansion characteristic, even if there is no visible damage, the staff can quickly find the short circuit point based on the appearance of the cable.

[0040] Because this invention employs a flexible rubber support frame 14, to make the expansion and pushing of the thermal expansion filler 17 onto the core 13 more directional during expansion, a support pad 19 is provided between the bottom of the core 13 and the bottom of the support groove 15. The width of the support pad 19 is adapted to the support groove 15, and the surface of the support pad 19 is provided with an arc-shaped surface adapted to the curvature of the core 13 surface. This method makes the movement of the core 13 more controllable through the movement of the support pad 19 within the support groove 15. Flame-retardant filler 20 is also provided in other locations within the filling area, namely the area between adjacent support grooves 15 and the area within the support groove 15 near the cable core surface, further enhancing the flame-retardant properties of the cable while filling.

Claims

1. A high flame-retardant cable, comprising a cable core and a plurality of flame-retardant mechanisms (1) spaced apart along the length of the cable core, wherein a filler strip is provided between adjacent flame-retardant mechanisms (1); the flame-retardant mechanisms (1) and the filler strip are wrapped around the cable core by a binding strap (2), wherein an outer sheath layer (3) is provided outside the binding strap (2). The flame-retardant mechanism (1) includes a collar (4) sleeved on the outside of the cable core and a plurality of elastic flame-retardant strips (5) arranged on the circumference of the collar (4). One end of the flame-retardant strip (5) is fixed to the collar (4), and the other end is pressed against the collar (4) by a pressing ring (6) sleeved on the outside of the collar (4). The flame-retardant strip (5) can be lifted up under elastic action when the pressing ring (6) is burned off, so as to form a flame-retardant disc on the circumference of the cable core. Its features are: An elastic support assembly is provided between two adjacent flame-retardant strips (5). Before the pressing ring (6) burns out, the elastic support assembly can be stored between the flame-retardant strips (5). After the pressing ring (6) burns out, it can open with the lifting action of the flame-retardant strips (5) and continuously apply a pushing force to the flame-retardant strips (5). The elastic support assembly can partially fill the space between adjacent flame-retardant strips (5) after the flame-retardant strips (5) are fully lifted. The elastic support assembly includes a metal spring sheet (7), which is bent into a U-shape and locked between the flame-retardant strips (5). The two ends of the metal spring sheet (7) are movably connected to the side wall of the flame-retardant strip (5). The two ends of the metal spring sheet (7) are provided with spherical shells (8), and the side wall of the flame-retardant strip (5) is provided with ball heads (9). The metal spring sheet (7) is locked on the ball heads (9) through the spherical shells (8) and forms a hinge with the flame-retardant strip (5). Each set of the elastic support components includes multiple metal springs (7), which are arranged along the length of the flame-retardant strip (5), and the U-shaped bending is successively fitted along the length of the flame-retardant strip (5). The flame-retardant strip (5) is a stamped part, and the flame-retardant strip (5) has stepped mounting grooves (10) stamped on both sides. The ball head (9) on the flame-retardant strip (5) is set in the mounting groove (10). The flame-retardant strip (5) and the pressing ring (6) are stamped with an end groove (11) for the pressing ring (6) to be inserted. The end groove (11) is located close to the two ends of the longest metal spring (7). The center of the metal spring (7) is provided with a protrusion (12). When the metal spring (7) is in the stored state, the middle of each metal spring (7) is pressed by the protrusion (12) on the adjacent metal spring (7).

2. The high flame-retardant cable according to claim 1, characterized in that: The cable core includes at least three wire cores (13), which are evenly distributed in a ring around the center of the cable core; each wire core (13) includes a conductive core material, and an insulation layer, a shielding layer and an inner sheath layer sequentially wrapped around the conductive core material from the inside to the outside; the area of ​​the cable core outside the wire cores (13) constitutes a filling area.

3. The high flame-retardant cable according to claim 2, characterized in that: A rubber support frame (14) is provided in the middle of the cable core along the length of the cable core. The rubber support frame (14) has several support grooves (15) that are evenly distributed in a ring shape, corresponding to the number of wire cores (13). The wire cores (13) are located in the support grooves (15).

4. The high flame-retardant cable according to claim 3, characterized in that: The rubber support skeleton (14) has a central hole (16) extending along the length of the rubber support skeleton (14) in the middle, and a thermal expansion filler (17) is provided in the central hole (16); an expansion port (18) communicating with the support groove (15) is provided on the hole wall opposite to the support groove (15) of the central hole (16).

5. The high flame-retardant cable according to claim 4, characterized in that: A pad (19) is provided between the bottom of the core (13) and the bottom of the support groove (15). The width of the pad (19) is adapted to the support groove (15), and the surface of the pad (19) is provided with an arc-shaped surface adapted to the curvature of the core (13). Flame-retardant filler (20) is provided in the area between adjacent support grooves (15) and in the area of ​​the support groove (15) near the surface of the cable core.

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