Low-smoke halogen-free crosslinked polyethylene insulated power cable

Abstract

This invention discloses a low-smoke halogen-free cross-linked polyethylene insulated power cable, belonging to the technical field of cross-linked polyethylene insulated power cables. It includes a cable core structure and a halogen-free low-smoke flame-retardant outer sheath. A rigid supplementary layer is provided between the cable core structure and the low-smoke flame-retardant outer sheath. The rigid supplementary layer includes multiple sets of protective structures arranged along the cable axis. Each set of protective structures includes a first annular member and a second annular member. An annular elastic bladder is provided between the first and second annular members, and multiple steel balls are disposed within the annular elastic bladder. Through this invention, when the cable is bent, the inner side of the annular elastic bladder is compressed, and the outer side is stretched. The internal steel balls roll and migrate from the inner side to the outer side, supplementing the structural rigidity of the outer region and alleviating the decrease in compressive strength caused by the expansion of the outer edge spacing. This ensures that the cable as a whole can maintain balanced compressive strength at the bending point.

Description

Technical Field

[0001] This invention belongs to the technical field of cross-linked polyethylene insulated power cables, and more specifically relates to a low-smoke halogen-free cross-linked polyethylene insulated power cable. Background Technology

[0002] Low-smoke halogen-free cross-linked polyethylene (XLPE) insulated power cables are environmentally friendly power transmission cables. They use XLPE as the core insulation material, and the outer sheath is made of halogen-free, low-smoke, flame-retardant material. When burning, they produce extremely low smoke and do not release toxic or corrosive gases, making them widely used in densely populated areas such as subways, airports, hospitals, and high-rise buildings. Their structure, from the inside out, mainly includes: a conductor layer, a conductor shielding layer, a XLPE insulation layer, an insulation shielding layer, a metallic shielding layer, filler and wrapping layers, and the outermost low-smoke halogen-free flame-retardant sheath layer.

[0003] The steel tape armor layer of power cables is typically formed by spirally winding galvanized steel tape, with a certain overlap between adjacent steel tape loops. This ensures the armor layer continuously and completely covers the inner structure, providing mechanical protection and enhancing compressive strength. However, during actual cable laying, the cable often needs to be bent and turned. At this time, the steel tape at the bend will shift due to stress deformation: the outer steel tape loops are stretched, and the overlap between loops gradually decreases or even moves away from each other; the inner steel tape loops are compressed, and the loops overlap and move closer together. When the deformation exceeds a certain extent, gaps will appear at the overlap of the outer steel tape, and in severe cases, the internal structure may be exposed, weakening the continuity of the armor layer and the compressive strength of the outer side of the bend.

[0004] There are two main reasons for this problem: First, the bending radius of the cable was too small during construction, and the bending range exceeded the standard allowable range; second, there were defects in the steel tape wrapping process, such as uneven wrapping tension and insufficient overlap, which caused the cable to expose the bottom on the outside of the bend when it was bent, affecting the compressive strength. Summary of the Invention

[0005] This invention addresses the problem of overly simplistic solutions in existing technologies by providing a significantly different solution. Belonging to the field of cross-linked polyethylene insulated power cable technology, this invention primarily provides a low-smoke, halogen-free cross-linked polyethylene insulated power cable to solve the technical problem mentioned in the background section where, during cable bending, the outer side of the bend sometimes exposes the insulated layer due to excessive bending, reducing the compressive strength of the outer side of the cable.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A low-smoke halogen-free cross-linked polyethylene insulated power cable includes a cable core structure and a halogen-free low-smoke flame-retardant outer sheath. A rigid supplementary layer is provided between the cable core structure and the low-smoke flame-retardant outer sheath. The rigid supplementary layer includes multiple sets of protective structures arranged along the cable axis. Each set of protective structures includes a first annular member and a second annular member formed by bending steel strip. An annular elastic bladder with a rectangular cross-section is provided between the first annular member and the second annular member. Multiple steel balls are provided inside the annular elastic bladder. When the cable is bent, the first annular member and the second annular member compress the annular elastic bladder located in the middle from a rectangular cross-section to a trapezoidal cross-section, and the steel balls inside the annular elastic bladder move from the inside to the outside of the cable bend.

[0008] Preferably, both the first annular component and the second annular component are provided with a connecting portion and a hook-shaped portion, and the hook-shaped portions in each pair of adjacent protective structures are in contact with each other.

[0009] Preferably, each hook-shaped portion has a wedge-shaped guide portion on its outer side.

[0010] Preferably, each of the connecting parts contacts and engages with the outer wall of the annular elastic bladder, and each of the connecting parts is provided with a plurality of L-shaped locking blocks arranged at equal intervals around it. Each locking block is engaged with an L-shaped locking groove, and the locking grooves are arranged at equal intervals on the outer wall of the annular elastic bladder.

[0011] Preferably, the cable core structure includes multiple conductors formed by twisting copper wires, each conductor having an extruded inner insulating layer, and a filler strip to ensure the roundness of the cable being provided in the gap between each two adjacent conductors.

[0012] Preferably, mica tape is provided on both the conductor and the filler strip, and the mica tape wraps around the outside of the conductor and the filler strip to form a fireproof layer.

[0013] Preferably, an insulating protective layer is provided on the outside of the fireproof layer, and both the insulating protective layer and the inner insulating lining are made of cross-linked polyethylene material.

[0014] Preferably, the outer side of the insulating protective layer is provided with an extruded waterproof layer, and the outer side of the waterproof layer is provided with a shielding layer formed by winding multiple metal wires.

[0015] Preferably, an elastic compressive strength layer is provided between the shielding layer and the rigid supplementary layer.

[0016] Preferably, the low-smoke flame-retardant outer sheath is located outside the rigid supplementary layer.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The present invention realizes the first and second annular parts made of steel strips through the rigid supplementary layer, which can provide strong rigid support and compressive strength. The elastic annular bladder has a certain deformation capacity. Under the alternating arrangement, the overall structure of the cable can adapt to a certain range of bending deformation while ensuring compressive strength and structural rigidity. This facilitates bending operations of the cable during the laying process and effectively reduces the difficulty of laying.

[0019] Furthermore, thanks to the hook-shaped and wedge-shaped guide parts, during assembly, each set of protective structures can be sequentially inserted along the cable axis and then quickly assembled by pressing, making the operation convenient and improving the efficiency of construction and assembly.

[0020] (2) By setting an annular elastic bladder and steel balls, the present invention achieves the following when the cable is bent during the laying process: on the inner side of the cable bend, the inner edges of the first and second annular parts approach each other, the inner part of the annular elastic bladder is squeezed and the internal space on the inner side is reduced; on the outer side of the cable bend, the outer edges of the first and second annular parts move away from each other, the outer part of the annular elastic bladder is stretched accordingly, and the internal space on the outer side is expanded. At this time, the steel balls in the annular elastic bladder will roll and migrate from the compressed inner area to the stretched outer area, forming a rigid filling of the increased gap on the outer side, which helps to supplement the structural rigidity of the outer area and alleviate the problem of reduced compressive strength caused by the expansion of the outer edge spacing.

[0021] Furthermore, the reduced distance between the inner edges of the first and second annular components on the inner side of the cable bend does not weaken the rigid compressive strength of the inner side, thus allowing the cable bend to maintain a relatively balanced compressive performance.

[0022] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0023] Figure 1 This is an overall schematic diagram of the present invention;

[0024] Figure 2 This is an overall exploded view of the present invention;

[0025] Figure 3 This is a schematic diagram of the rigid supplementary layer of the present invention;

[0026] Figure 4 This is a schematic diagram of the protective structure of the present invention;

[0027] Figure 5 This is an exploded view of the protective structure of the present invention;

[0028] Figure 6 This is a schematic diagram of the first and second annular components of the present invention;

[0029] Figure 7 For the present invention Figure 6 Enlarged diagram of area A;

[0030] Figure 8 This is a schematic cross-sectional view of the first annular component of the present invention;

[0031] Figure 9 For the present invention Figure 8 Enlarged diagram of area B;

[0032] Figure 10 This is a schematic diagram of the annular elastic bladder of the present invention;

[0033] Figure 11 This is a schematic cross-sectional view of the connection between the two sets of protective structures of the present invention;

[0034] Figure 12 This is an exploded view of the cable core structure of the present invention;

[0035] Figure 13 This is a schematic diagram of the shielding layer of the present invention;

[0036] Figure 14 This is a schematic diagram of the annular elastic capsule-shaped variable cross-section at the cable bend of the present invention.

[0037] In the diagram: 1. Cable core structure; 11. Conductor; 12. Inner insulation layer; 13. Filler strip; 14. Fireproof layer; 141. Mica tape; 15. Insulating protective layer; 2. Rigid supplementary layer; 21. First annular component; 22. Second annular component; 23. Annular elastic bladder; 231. Slot; 24. Steel ball; 25. Connecting part; 26. Hook-shaped part; 27. Wedge-shaped guide part; 28. Locking block; 3. Low smoke flame retardant outer sheath; 4. Waterproof layer; 5. Shielding layer; 51. Metal wire; 6. Elastic compression-resistant layer. Detailed Implementation

[0038] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0039] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] For the implementation examples, please refer to the appendix. Figure 1-14 As shown, a low-smoke halogen-free cross-linked polyethylene insulated power cable includes a cable core structure 1 and a halogen-free low-smoke flame-retardant outer sheath 3. A rigid supplementary layer 2 is provided between the cable core structure 1 and the low-smoke flame-retardant outer sheath 3. The rigid supplementary layer 2 includes multiple sets of protective structures arranged along the cable axis. Each set of protective structures includes a first annular member 21 and a second annular member 22 formed by bending steel strip. An annular elastic bladder 23 with a rectangular cross-section is provided between the first annular member 21 and the second annular member 22. Multiple steel balls 24 are provided inside the annular elastic bladder 23. When the cable is bent, the first annular member 21 and the second annular member 22 will be located in the middle. The annular elastic bladder 23, initially rectangular in cross-section, is compressed into a trapezoidal structure. Specifically, the portion of the annular elastic bladder 23 located outside the cable bend is stretched (the distance between the outer edges of the first annular member 21 and the second annular member 22 increases at the bend), while the portion located inside the cable bend is compressed (the inner edges of adjacent first annular members 21 and the second annular member 22 move closer together at the bend). Due to the compression effect of the first annular member 21 and the second annular member 22, and the resulting change in the internal space of the annular elastic bladder 23, the steel ball 24 inside the annular elastic bladder 23 moves from the inside to the outside of the cable bend (as shown in the attached diagram). Figure 14 As shown, this supplements the rigidity of the outer side of the cable bend, avoiding the problem of weakened strength on the outer side of the bend due to the increased distance between the outer edges of the first ring member 21 and the second ring member 22.

[0042] Please refer to the appendix carefully. Figure 4-11As shown, both the first annular member 21 and the second annular member 22 are provided with connecting portions 25 and hook-shaped portions 26. The hook-shaped portions 26 in each pair of adjacent protective structures contact and cooperate with each other. Since the first annular member 21 and the second annular member 22 are made of bent steel strips, they have a certain elastic deformation capability. Therefore, the adjacent pairs of protective structures can be quickly connected by extrusion. Each hook-shaped portion 26 is provided with a wedge-shaped guide portion 27 on its outer side. During the extrusion process, two adjacent wedge-shaped guide portions 27 will contact each other first, and the inclined surface of the wedge-shaped guide portion 27 will... The use of hooks reduces the squeezing force, which facilitates the quick connection of the two hook-shaped parts 26. Each of the connecting parts 25 contacts and engages with the outer wall of the annular elastic bladder 23. Each of the connecting parts 25 is equidistantly surrounded by multiple L-shaped locking blocks 28. Each locking block 28 engages with an L-shaped locking groove 231, and the locking grooves 231 are equidistantly arranged on the outer wall of the annular elastic bladder 23. Through the locking blocks 28 and the locking grooves 231, the first annular part 21 and the second annular part 22 can be installed on the two side walls of the annular elastic bladder 23.

[0043] Please refer to the appendix carefully. Figure 2 and attached Figure 12-13 As shown, the cable core structure 1 includes multiple conductors 11 formed by twisting copper wires. Each conductor 11 is provided with an extruded inner insulation layer 12. A filler strip 13 is provided in the gap between each two adjacent conductors 11 to ensure the roundness of the cable. Mica tape 141 is provided on both the conductors 11 and the filler strip 13. The mica tape 141 wraps around the outside of the conductors 11 and the filler strip 13 to form a fireproof layer 14. At the same time, the winding of the mica tape 141 plays a certain positioning role for the conductors 11 and the filler strip 13, further ensuring the roundness and providing a physical basis for the deformation of the protective structure when bent. An insulating protective layer 15 is provided on the outside of the fireproof layer 14. Both the insulating protective layer 15 and the inner insulation layer 12 are made of cross-linked polyethylene material, which has the characteristics of high current carrying capacity, light weight and high temperature resistance.

[0044] An extruded waterproof layer 4 is provided on the outside of the insulating protective layer 15. A shielding layer 5, formed by winding multiple metal wires 51, is provided on the outside of the waterproof layer 4 to suppress electromagnetic interference generated by the internal electric field of the cable. An elastic compression-resistant layer 6 is provided between the shielding layer 5 and the rigid supplementary layer 2. The low-smoke flame-retardant outer sheath 3 is located on the outside of the rigid supplementary layer 2. The low-smoke flame-retardant outer sheath 3 is made of halogen-free low-smoke flame-retardant material. It produces very little smoke and does not release toxic or corrosive gases when burning. It is widely used in densely populated places such as subways, airports, hospitals, and high-rise buildings.

[0045] The present invention has been described by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A low-smoke halogen-free cross-linked polyethylene insulated power cable, comprising a core structure (1) and a halogen-free low-smoke flame-retardant outer sheath (3), characterized in that... A rigid supplementary layer (2) is provided between the cable core structure (1) and the low-smoke flame-retardant outer sheath (3). The rigid supplementary layer (2) includes multiple sets of protective structures arranged along the cable axis. Each set of protective structures includes a first ring (21) and a second ring (22) formed by bending steel strip. An annular elastic bladder (23) with a rectangular cross-section is provided between the first ring (21) and the second ring (22). Multiple steel balls (24) are provided inside the annular elastic bladder (23). When the cable is bent, the first ring (21) and the second ring (22) squeeze the annular elastic bladder (23) located in the middle from the rectangular cross-section to the trapezoidal cross-section, and the steel balls (24) inside the annular elastic bladder (23) move from the inside to the outside of the cable bend.

2. The low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 1, characterized in that, The first annular member (21) and the second annular member (22) are each provided with a connecting part (25) and a hook-shaped part (26), and the hook-shaped parts (26) in each two adjacent sets of protective structures are in contact with each other.

3. The low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 2, characterized in that, Each hook-shaped portion (26) has a wedge-shaped guide portion (27) on its outer side.

4. The low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 2, characterized in that, Each of the connecting parts (25) is in contact with the outer wall of the annular elastic bladder (23). Each of the connecting parts (25) is provided with a plurality of L-shaped locking blocks (28) at equal intervals. Each locking block (28) is engaged with an L-shaped locking groove (231), and the locking groove (231) is provided at equal intervals on the outer wall of the annular elastic bladder (23).

5. The low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 1, characterized in that, The cable core structure (1) includes a plurality of conductors (11) formed by twisting copper wires. Each conductor (11) is provided with an extruded inner insulation layer (12). A filler strip (13) is provided in the gap between each two adjacent conductors (11) to ensure the roundness of the cable.

6. A low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 5, characterized in that, Mica tape (141) is provided on both the conductor (11) and the filler strip (13), and the mica tape (141) wraps around the outside of the conductor (11) and the filler strip (13) to form a fireproof layer (14).

7. A low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 6, characterized in that, An insulating protective layer (15) is provided on the outside of the fireproof layer (14), and both the insulating protective layer (15) and the inner insulating layer (12) are made of cross-linked polyethylene material.

8. A low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 7, characterized in that, An extruded waterproof layer (4) is provided on the outside of the insulating protective layer (15), and a shielding layer (5) formed by winding multiple metal wires (51) is provided on the outside of the waterproof layer (4).

9. A low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 8, characterized in that, An elastic compressive layer (6) is provided between the shielding layer (5) and the rigid supplementary layer (2).

10. A low-smoke halogen-free cross-linked polyethylene insulated power cable according to claim 1, characterized in that, The low-smoke flame-retardant outer sheath (3) is located outside the rigid supplementary layer (2).

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