A copper alloy high-current flexible medium voltage power cable

Abstract

The application belongs to the technical field of cables, and particularly relates to a copper alloy large-current flexible medium-voltage power cable; the copper alloy large-current flexible medium-voltage power cable comprises an inner conductor, a conductor shielding layer, an electrical insulation layer, an electric field shielding layer, a metal shielding layer, a bistable layer and an outer sheath; the bistable layer is composed of inner and outer bistable layers with a long circular cross section, and a straight line area and an arc area are formed between the two; the arc area is provided with a net structure, and the straight line area is provided with a first supporting structure and a second supporting structure corresponding to each other. In a straight line state, the supporting structures are in contact with each other, the cable has high bending stiffness and is rigid; when the cable is bent, the supporting structures are separated, the net structure is deformed, the bending stiffness is suddenly reduced, and the cable is flexible. The bistable layer is used for realizing controllable switching of rigid and flexible states, and is suitable for complex working conditions such as self-supporting crossing and flexible bending of mobile power supply, ship tunnels and robot cables.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and in particular to a copper alloy high-current flexible medium-voltage power cable. Background Technology

[0002] In medium-voltage (6kV–35kV) and high-current (200A–1500A) applications, power cables typically need to balance electrical and mechanical performance. Traditional power cables generally consist of an inner conductor, insulation layer, metallic shielding layer, and outer sheath; their overall flexibility is determined by the materials themselves and their structure. Ordinary cables either have good flexibility, facilitating winding and unwinding, but are prone to sagging during straight laying and require additional supports; or they employ armored structures (such as steel tape armor) to improve mechanical strength, enabling self-support, but these cables are difficult to bend and unsuitable for applications requiring frequent winding and unwinding or involving curved lines.

[0003] With the development of applications such as mobile medium-voltage power supply vehicles, integrated cabling inside ships or tunnels, and robotic cables, more requirements are placed on cables: when laying or operating in straight sections, it is desirable for cables to remain rigid, be able to support themselves to cross ditches, and run straight along walls without sagging; when reeling in and out, bending, or moving with robotic arms, it is desirable for cables to have good flexibility, be able to bend to a small radius with low bending resistance. Existing cables are difficult to meet these two opposing performance requirements at the same time.

[0004] Therefore, it is necessary to develop a new type of cable that can actively switch between rigid and flexible characteristics according to the external stress state, so that the cable is rigid in a straight state and automatically becomes flexible in a bending state, thereby adapting to complex and ever-changing laying and operating environments. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a copper alloy high-current flexible medium-voltage power cable, aiming to solve the problems in the background technology.

[0006] To achieve the above-mentioned technical objectives, the specific technical solution of the present invention is as follows: The present invention proposes a copper alloy high-current flexible medium-voltage power cable, comprising, from the inside out, an inner conductor, a conductor shielding layer, an electrical insulation layer, an electric field shielding layer, a metal shielding layer, and an outer sheath; it also includes a bistable layer disposed between the metal shielding layer and the outer sheath, wherein the bistable layer enables the cable to simultaneously possess rigidity and flexibility characteristics; the bistable layer comprises an inner stable layer and an outer stable layer, both of which have an elongated oval cross-section, the elongated oval being composed of two parallel straight line segments and two symmetrical semicircular arcs; the inner stable layer and the outer stable layer form two vertically distributed straight line regions and two horizontally symmetrically distributed arc regions; within the straight line regions, the inner wall of the outer stable layer is provided with a plurality of first support structures along the circumferential direction, and the outer wall of the inner stable layer is provided with second support structures corresponding to the first support structures;

[0007] When the cable is in a straight state, the first support structure and the second support structure are in contact with each other to form a support point, and the cable exhibits rigid characteristics.

[0008] When the cable is in a bent state, the first support structure and the second support structure are misaligned and separated from each other, the support structure collapses, and the cable exhibits flexible characteristics.

[0009] As a preferred embodiment of the present invention, both the first support structure and the second support structure are in the shape of an isosceles trapezoid or a hemispherical structure.

[0010] As a preferred embodiment of the present invention, the contact surfaces of the first support structure and the second support structure are respectively provided with micro-teeth that can engage with each other.

[0011] As a preferred embodiment of the present invention, the micro-teeth are isosceles trapezoids or triangles, and the number of micro-teeth on each support structure is 5 to 8.

[0012] As a preferred embodiment of the present invention, the inner stable layer and the outer stable layer are made of elastic metal strip, and a mesh structure is provided in the arc-shaped region, wherein the mesh of the mesh structure is rhomboid or hexagonal.

[0013] As a preferred embodiment of the present invention, the two arc-shaped regions of the bistable layer are provided with a filling layer, the cross-section of the filling layer is semi-circular and is interference-fitted into the arc-shaped regions.

[0014] As a preferred embodiment of the present invention, the inner conductor is composed of one or more copper busbars, and the surface is stamped with stripes.

[0015] As a preferred embodiment of the present invention, the conductor shielding layer is an extruded semi-conductive layer made of cross-linkable semi-conductive polyethylene, which is tightly bonded to the surface of the inner conductor; the electrical insulation layer is made of cross-linked polyethylene; the electric field shielding layer is a semi-conductive shielding layer made of cross-linkable semi-conductive polyethylene or semi-conductive ethylene propylene rubber; the conductor shielding layer, the electrical insulation layer and the electric field shielding layer are formed by a three-layer co-extrusion process in one extrusion.

[0016] As a preferred embodiment of the present invention, both the first support structure and the second support structure are integrally stamped.

[0017] As a preferred technical solution of the present invention, the metal shielding layer is made of longitudinally wrapped aluminum strip, which is longitudinally wrapped and then welded into a tubular shape, and the weld is made by argon arc welding and leveled by pressure roller.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. This invention establishes a bistable layer consisting of an inner and outer stable layer, and configures mutually contacting support structures in the straight section. This enables the cable to exhibit high bending stiffness and rigidity when in a straight state, allowing it to self-support across trenches or maintain a straight laying position. When subjected to sufficient bending moment, the support structure separates and collapses, the bending stiffness drops sharply, and the cable transitions to a flexible state, facilitating winding, unwinding, or bending with a robotic arm. This achieves controllable switching between the rigid and flexible states of the cable, meeting the needs of complex working conditions such as mobile medium-voltage power supply vehicles, ship tunnels, and robot cables. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a copper alloy high-current flexible medium-voltage power cable structure proposed in this invention.

[0021] Figure 2 This is a three-dimensional schematic diagram of a copper alloy high-current flexible medium-voltage power cable proposed in this invention.

[0022] Figure 3 This is a schematic diagram of the bistable layer proposed in this invention.

[0023] Figure 4 This is a front view schematic diagram of the bistable layer proposed in this invention.

[0024] Figure 5 This is an axial cross-sectional view of the bistable layer proposed in this invention.

[0025] The corresponding names of the reference numerals in the figure are as follows: 1. Inner conductor; 2. Conductor shielding layer; 3. Electrical insulation layer; 4. Electric field shielding layer; 5. Metal shielding layer; 6. Bistable layer; 7. Outer sheath; 8. Filling layer; 61. Outer stable layer; 62. Inner stable layer; 63. Arc region; 64. Straight region; 65. Mesh structure; 66. First support structure; 67. Second support structure; 68. Micro-tooth. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1 To be continued Figure 5 This embodiment provides a detailed description of the copper alloy high-current flexible medium-voltage power cable. This embodiment is merely illustrative and does not constitute any limitation on the scope of protection of this invention.

[0027] As attached Figure 1 Appendix Figure 2 As shown, the power cable of this embodiment includes an inner conductor 1, and the outer side of the inner conductor 1 is wrapped with a conductor shielding layer 2, an electrical insulation layer 3, an electric field shielding layer 4, a metal shielding layer 5, a bistable layer 6, and an outer sheath 7 from the inside out. The cable cross-section is generally oblong, suitable for high current transmission scenarios with medium voltage levels of 6kV to 35kV and rated currents of 200A to 1500A.

[0028] Specifically, in this embodiment, the inner conductor 1 is made of copper alloy and consists of one or more copper busbars with striped patterns pressed onto its surface; the conductor shielding layer 2 is an extruded semi-conductive layer made of cross-linkable semi-conductive polyethylene, which is tightly bonded to the surface of the inner conductor 1 and co-extruded with the electrical insulation layer 3; the electrical insulation layer 3 is made of cross-linked polyethylene; the insulation layer is produced using a three-layer co-extrusion process (extruded once with the conductor shielding layer 2 and the electric field shielding layer 4), with an eccentricity not exceeding 8%; the electric field shielding layer 4 is a semi-conductive shielding layer, which is co-extruded with the electrical insulation layer 3. The insulating layer 3 is extruded simultaneously, and the material is cross-linkable semi-conductive polyethylene or semi-conductive ethylene propylene rubber; the volume resistivity is the same as that of the conductor shielding layer 2; the function of the electric field shielding layer 4 is to uniformly distribute the electric field on the outer surface of the insulating layer and prevent partial discharge between the electrical insulating layer 3 and the metal shielding layer 5; the metal shielding layer 5 is made of longitudinally wrapped aluminum strip, which is longitudinally wrapped and welded into a tube shape, and the weld is argon arc welded and leveled by pressure rollers; the outer sheath 7 is made of high-density polyethylene material, with an extrusion thickness of 1.50mm to 2.5mm, and the surface of the sheath may have raised color strips or embossed markings.

[0029] As attached Figure 3 To be continued Figure 5As shown, the bistable layer 6 in this embodiment includes an inner stable layer 62 and an outer stable layer 61. The cross-sections of both the inner stable layer 62 and the outer stable layer 61 are oblong, that is, composed of two parallel straight line segments and two symmetrical semicircular arcs. Two straight line regions 64 and two arc-shaped regions 63 are formed between the inner stable layer 62 and the outer stable layer 61. The two straight line regions 64 are distributed vertically, and the two arc-shaped regions 63 are distributed symmetrically from left to right.

[0030] Specifically, the inner stable layer 62 and the outer stable layer 61 are made of high-strength elastic metal strip. The strip thickness is 0.3mm to 0.5mm for the inner stable layer 62 and 0.4mm to 0.7mm for the outer stable layer 61. The strip is continuously rolled into a tubular structure with an elongated oval cross-section. After forming, a mesh structure 65 is processed in the arc-shaped area 63 using a punching die. The mesh of the mesh structure 65 is rhomboid or hexagonal. The inner wall of the outer stable layer 61 is provided with several first support structures 66 along the circumference, and the outer wall of the inner stable layer 62 is provided with second support structures 67. Both are integrally stamped with the outer stable layer 61 or the inner stable layer 62. Among them, in each straight area 64, the first support structure 66 is provided with several first support structures 66 along the circumference. The inner stable layer 62 is provided with second support structures 67. Both are integrally stamped with the outer stable layer 61 or the inner stable layer 62. Support structures 66 are installed every 10mm to 25mm along the length of the cable and 2 to 4 along the width of the cable; no support structures are installed in the arc-shaped area 63; each support structure is an isosceles trapezoid or hemispherical; the second support structure 67 has the same dimensions but protrudes in opposite directions; when the cable is in a straight state, the end face of the first support structure 66 contacts the end face of the second support structure 67, forming a support point, and the cable rigidity is strengthened, exhibiting rigid characteristics; when the cable is in a bent state, relative sliding occurs between the inner stable layer 62 and the outer stable layer 61, the end face of the first support structure 66 separates from the second support structure 67, the support structure collapses, the cable rigidity decreases, exhibiting flexible characteristics.

[0031] In a preferred embodiment of the present invention, micro-teeth 68 that can engage with each other are respectively machined on the contact surfaces of the first support structure 66 and the second support structure 67. The micro-teeth 68 are used to lock the first support structure 66 and the second support structure 67 into a stable structure and improve the rigidity characteristics of the cable.

[0032] Specifically, the micro-tooth 68 has an isosceles trapezoidal or triangular shape, and the number of micro-tooth 68 on each support structure is 5 to 8.

[0033] As a preferred embodiment of the present invention, a filling layer 8 is provided in the two arc-shaped regions 63 of the bistable layer 6. The filling layer 8 is made of low-density foamed polyethylene (EPE, density 0.03~0.06g / cm³) or silicone rubber foam material (compression set ≤10%).

[0034] Specifically, the cross-section of the filling layer 8 is semi-circular, and its thickness in its natural state is 0.2mm to 0.5mm greater than the radial gap of the arc-shaped region 63. It is slightly interference-fitted, compressible, and helps maintain the structural stability of the bistable layer 6, prevents unexpected collapse, and facilitates recovery after bending.

[0035] The working process of bistable layer 6 in this embodiment:

[0036] Straight Rigid State: When the cable is laid in a straight state, the inner stable layer 62 and the outer stable layer 61 are arranged coaxially. The first support structure 66 and the second support structure 67 in the straight area 64 are in contact with each other to form a support point. The micro teeth 68 are engaged with each other to form a locking state. At this time, the combined bending stiffness can reach 3.2 to 4.5 times the stiffness of a single stable layer, and the cable exhibits rigid characteristics.

[0037] Bending flexibility state: When the cable is subjected to sufficient external bending moment, the bending radius first undergoes tension and compression in the arc region 63. Since the bending radii of the inner stable layer 62 and the outer stable layer 61 are different, they undergo relative axial slippage. This slippage force overcomes the locking force of the micro-tooth 68, causing the first support structure 66 to separate from the second support structure 67. The micro-tooth 68 disengages, and the support structure collapses. At the same time, the mesh structure 65 in the arc region 63 undergoes in-plane deformation, the filling layer 8 is compressed, and the overall bending stiffness of the bistable layer 6 drops sharply by 30-50%, and the cable exhibits flexible characteristics.

[0038] The cable application scenario in this embodiment is as follows:

[0039] Mobile medium-voltage power supply vehicle: The cable is flexible when on the reel, making it easy to reel in and out; after being unloaded, it switches to a rigid state and can self-support itself to cross ditches;

[0040] Laying in ships or tunnels: straight sections need to remain straight, but they need to be temporarily softened at bends and then restored to rigidity after the bend;

[0041] Robot cables: The cables are rigid when the robotic arm moves in a straight line to prevent sagging; the cables become flexible when the joints bend, and bend accordingly.

[0042] Finally, it should be noted that in the description of this invention, the terms "vertical," "upper," "lower," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A copper alloy high-current flexible medium-voltage power cable, comprising, from the inside out, an inner conductor (1), a conductor shielding layer (2), an electrical insulation layer (3), an electric field shielding layer (4), a metal shielding layer (5), and an outer sheath (7); characterized in that: It also includes a bistable layer (6) disposed between the metal shielding layer (5) and the outer sheath (7), wherein the bistable layer (6) enables the cable to have both rigid and flexible characteristics; The bistable layer (6) includes an inner stable layer (62) and an outer stable layer (61). The cross-sections of the inner stable layer (62) and the outer stable layer (61) are both oblong. The oblong is composed of two parallel straight line segments and two symmetrical semicircular arcs. The inner stable layer (62) and the outer stable layer (61) form two vertically distributed straight regions (64) and two horizontally symmetrically distributed arc-shaped regions (63). Within the straight area (64), the inner wall of the outer stable layer (61) is provided with a plurality of first support structures (66) along the circumferential direction, and the outer wall of the inner stable layer (62) is provided with a second support structure (67) corresponding to the first support structure (66). When the cable is in a straight state, the first support structure (66) and the second support structure (67) are in contact with each other to form a support point, and the cable exhibits rigid characteristics. When the cable is in a bent state, the first support structure (66) and the second support structure (67) are misaligned and separated from each other, the support structure collapses, and the cable exhibits flexible characteristics; The first support structure (66) and the second support structure (67) are respectively provided with micro teeth (68) that can engage with each other. The inner stable layer (62) and the outer stable layer (61) are made of elastic metal strips, and a mesh structure (65) is provided in the arc-shaped area (63). The mesh of the mesh structure (65) is rhomboid or hexagonal. The bistable layer (6) has a filling layer (8) in the two arc-shaped regions (63), and the cross-section of the filling layer (8) is semi-circular and is interference-fitted into the arc-shaped regions (63).

2. The copper alloy high-current flexible medium-voltage power cable according to claim 1, characterized in that: Both the first support structure (66) and the second support structure (67) are in the shape of an isosceles trapezoid or a hemispherical structure.

3. The copper alloy high-current flexible medium-voltage power cable according to claim 2, characterized in that: The micro-teeth (68) are in the shape of an isosceles trapezoid or triangle, and the number of micro-teeth (68) on each support structure is 5 to 8.

4. The copper alloy high-current flexible medium-voltage power cable according to claim 1, characterized in that: The inner conductor (1) is composed of one or more copper busbars, and the surface is stamped with stripes.

5. The copper alloy high-current flexible medium-voltage power cable according to claim 1, characterized in that: The conductor shielding layer (2) is an extruded semi-conductive layer made of cross-linkable semi-conductive polyethylene, which is tightly bonded to the surface of the inner conductor (1); the electrical insulation layer (3) is made of cross-linked polyethylene; the electric field shielding layer (4) is a semi-conductive shielding layer made of cross-linkable semi-conductive polyethylene or semi-conductive ethylene propylene rubber; the conductor shielding layer (2), the electrical insulation layer (3) and the electric field shielding layer (4) are formed by a three-layer co-extrusion process in one extrusion.

6. The copper alloy high-current flexible medium-voltage power cable according to claim 1, characterized in that: Both the first support structure (66) and the second support structure (67) are integrally stamped.

7. The copper alloy high-current flexible medium-voltage power cable according to claim 1, characterized in that: The metal shielding layer (5) is made of longitudinally wrapped aluminum strip. The aluminum strip is longitudinally wrapped and then welded into a tubular shape. The weld is made of argon arc welding and leveled by pressure roller.

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