Polyethylene insulated power cable

Abstract

The application relates to the technical field of mechanical protection of power cables, and particularly discloses a polyethylene insulated power cable, which comprises a cable core and an inner sheath, a spiral elastic supporting member and an outer sheath which are arranged outside the cable core from inside to outside. The spiral elastic supporting member comprises a continuous spiral piece and a plurality of elastic pieces which are integrally connected with the continuous spiral piece, the continuous spiral piece forms a plurality of spiral turns which are arranged in sequence along the cable axial direction, and a cut is formed between adjacent elastic pieces; each elastic piece is bent at a root portion relative to the continuous spiral piece and extends towards an adjacent spiral turn, and a supporting portion of the elastic piece abuts against the spiral turn adjacent to the cable axial direction. The elastic piece forms radial support for the adjacent spiral turn, the adjacent spiral turn limits the deformation stroke of the elastic piece, the load of the continuous spiral piece is diffused, the local deformation and unloading recovery of the segmented elastic piece are matched, and thus the mechanical protection and the bending adaptability of the cable are considered.

Description

Technical Field

[0001] This invention relates to the field of mechanical protection technology for power cables, specifically to a polyethylene insulated power cable in which a spiral elastic support member is provided between the inner and outer sheaths to improve the cable's structural adaptability to radial compression, local impact, and point load. Background Technology

[0002] Polyethylene insulated power cables typically consist of a conductor, insulation structure, shielding structure, and an outer sheath. During manufacturing, coiling, transportation, laying, installation, and operation, the cable may be subjected to clamping, stone pressure, tool impact, trench backfill compression, and other localized mechanical forces. When the area affected by the external load is small, the load, after being transferred inward through the outer sheath, tends to concentrate in a small area, causing the inner sheath, shielding layer, and insulation layer to experience high localized compressive stress. To reduce the impact of mechanical loads on the internal structure of the cable, existing solutions typically employ methods such as increasing sheath thickness, installing steel tape or wire armor, adding flexible buffer layers, and installing continuous metallic protective layers.

[0003] Chinese patent document CN212084709U discloses an armored, pressure-resistant cable. The cable body includes annealed copper, an XLPE insulation layer, a PVC inner sheath, an inner armor layer, an outer armor layer, and a PVC outer sheath. The inner armor layer is spirally wound around the periphery of the PVC inner sheath, and the outer armor layer is formed by braiding multiple galvanized steel wires. This design utilizes a two-layer armor structure to improve the overall structural strength of the cable, with the spirally wound inner armor layer forming a continuous mechanical protective layer.

[0004] Chinese patent document CN206711645U discloses a pressure-resistant and flame-retardant cable. It features a pressure-resistant buffer layer between the core and the cable sheath, with an air-filled buffer layer within the cavity structure of this buffer layer. A rubber layer is also provided on the outside of the pressure-resistant buffer layer, forming an elastic space between the buffer layer and the rubber layer. This design primarily alleviates the compression of the core caused by external pressure through elastic materials and the elastic space.

[0005] As can be seen from the above technical approaches, continuous steel strips, steel wires, or other armored components can form a continuous protection path based on the strength and stiffness of the material itself, while flexible buffer materials can absorb some of the impact energy through compression deformation. Under the localized radial compression and point load conditions that this application focuses on, if continuous rigid components are mainly relied upon to improve compressive strength, the structural resistance that the cable needs to overcome when bending will increase accordingly as the component thickness or stiffness increases. If continuous flexible materials are mainly relied upon for compression buffering, the load is still mainly borne by the material near the compression point, and the flexible material itself does not form a definite load-bearing path that continuously diffuses the load along the cable length. If a structure combining independent elastic supports and continuous load-bearing components is used, the positioning and connection of multiple supports, as well as the dislocation and instability problems after compression, also need to be considered.

[0006] Therefore, a mechanical protection structure is needed that can form a continuous load-bearing path along the cable length while also generating segmented elastic deformation at local pressure points. This allows the external local load to first spread from the continuous structure to adjacent areas, and then be borne by multiple separated elastic support units. The elastic support units should obtain stable reaction force and stroke limitation during deformation, so as to take into account local buffering, unloading recovery and cable bending adaptability. Summary of the Invention

[0007] This invention provides a polyethylene insulated power cable, which aims to solve the problem that existing mechanical protection structures cannot simultaneously form a continuous load diffusion path and a segmented elastic support path, and that it is difficult to balance the compressive strength, unloading recovery ability and cable bending adaptability under local pressure.

[0008] A polyethylene insulated power cable includes a cable core and an inner sheath, a helical elastic support member, and an outer sheath disposed from the inside out on the outside of the cable core. The cable core includes a conductor and a polyethylene insulation layer covering the conductor. The helical elastic support member includes a continuous helical plate extending helically around the cable core and a plurality of elastic plates integrally connected to the continuous helical plate. The continuous helical plate forms a plurality of sequentially arranged helical coils along the cable axial direction. The plurality of elastic plates are spaced apart along the length direction of the continuous helical plate, and a cut is formed between adjacent elastic plates. Each elastic plate includes a root integrally connected to the continuous helical plate and a support portion formed by bending the root relative to the continuous helical plate. The elastic plate extends from the root toward the adjacent helical coil along the cable axial direction. The support portion abuts against the adjacent helical coil so that the elastic plate provides radial support to the adjacent helical coil, and the adjacent helical coil limits the deformation stroke of the elastic plate.

[0009] Its effect is as follows: the continuous spiral blades extend continuously around the cable core, ensuring that each compressed spiral ring is continuously connected to its preceding and following sections along the length of the strip. External local pressure is transmitted to the compressed spiral ring via the outer sheath, and the bending deformation of the compressed area can affect adjacent sections of the continuous spiral blades, thus transferring part of the load forward and backward along the spiral direction. Although multiple elastic plates are integrally connected to the continuous spiral blades, adjacent elastic plates are separated by slits. Therefore, one or more elastic plates at the compressed position can independently bend, compress, rotate, or slip within a limited range, while elastic plates not directly compressed maintain their original support state. After the support portion of the elastic plate abuts against the adjacent spiral ring, the elastic plate provides radial support to the adjacent spiral ring, while the adjacent spiral ring simultaneously provides a reaction force to the elastic plate and restricts its continued opening, flipping, or excessive deformation in the direction away from the support position. This forms a closed load transfer relationship of "compressed spiral ring—elastic plate—adjacent spiral ring—continuous spiral blade". The continuous spiral plates are responsible for diffusing local loads over a long range, while the segmented elastic plates are responsible for generating recoverable deformation at local locations and absorbing some impact energy. The two are mutually supported and restrained by adjacent spiral coils, transforming the local point load from being borne by a single pressure point to being shared by multiple support points along the spiral direction. After the external load is removed, the restoring force generated by the elastic plates within the material's elastic range pushes the pressure spiral coil back to its initial position. When the cable bends, each elastic plate can adapt to different coil spacing changes on the inner and outer sides of the bend. Therefore, continuous load-bearing and local elastic response can be achieved without designing the entire mechanical protective layer as a high-rigidity continuous shell.

[0010] Preferably, the continuous spiral blade and the plurality of elastic blades are formed from the same strip blank. The strip blank includes a main strip region that maintains continuity and an elastic blade forming region located on one side of the main strip region. The elastic blade forming region has a plurality of slits spaced apart along the length of the strip blank. Each slit extends from one edge of the strip blank toward the main strip region without cutting off the main strip region, thereby forming a plurality of elastic blades that are spaced apart from each other and whose roots are integrally connected to the main strip region. The advantage is that the main strip region remains continuous during the cutting process, and after spiral winding, an uninterrupted continuous spiral blade can be formed; the elastic blade forming region obtains a plurality of independently deformable elastic blades through the spaced slits extending from the side toward the main strip region. The continuous bearing part and the segmented elastic part are directly formed from the same blank, and the roots of the elastic blades do not need to be welded, riveted, or installed piece by piece, which can reduce independent parts and connection positions, and the initial position of each elastic blade relative to the continuous spiral blade is determined by the strip blank itself.

[0011] Preferably, each elastic sheet, from its root towards its free end, sequentially includes a bending portion, an elastic deformation portion, and a support portion, wherein the support portion abuts against the inner surface or edge of the adjacent spiral coil. The effect is that the root portion connects the elastic sheet to the continuous spiral sheet; the bending portion determines the starting position of the elastic sheet bending outward from the reference surface of the continuous spiral sheet towards the support direction; the elastic deformation portion provides the main deformation stroke during compression; and the support portion transmits the supporting force generated by the elastic sheet to the adjacent spiral coil. By separating the connection, deformation, and contact functions along the length of the elastic sheet, the force path and deformation position of the elastic sheet can be more clearly defined.

[0012] Preferably, in the free state, the distance between the root and the support portion along the cable radial direction is greater than the distance between the root and the corresponding abutment position of the adjacent spiral coil along the cable radial direction in the assembled state, so that the elastic sheet is in a pre-tightened state in the assembled state; there is an axial deformation gap between adjacent spiral coils along the cable axial direction. The effect is that after the spiral winding is completed, the adjacent spiral coils will exert an initial pressing force on the support portion, causing the elastic sheet to form a pre-tightened deformation. The support portion maintains contact with the adjacent spiral coils when not subjected to abnormal external loads, thereby reducing repeated detachment and collision of the support portion during handling, vibration, or bending. The axial deformation gap maintained between adjacent spiral coils allows the compressed spiral coils to move closer together axially to a limited extent, and allows for differences in the spacing between the inner and outer coils when the cable is bent.

[0013] Preferably, the support portion slides against the adjacent spiral coil, and the continuous spiral plate is provided with a limiting portion, which is used to limit the sliding distance of the support portion relative to the adjacent spiral coil. The effect is that the sliding contact allows the elastic plate to adjust its tilt angle by changing the contact position when the cable is bent or locally compressed, reducing the forced torsion caused by the relative displacement of adjacent spiral coils; the limiting portion restricts the sliding within a predetermined range, preventing the support portion from leaving the effective support area due to continuous sliding.

[0014] Preferably, the support portion and the adjacent spiral ring have an overlap length along the sliding direction at the initial assembly position, and the maximum sliding distance defined by the limiting portion is less than the overlap length. The limiting portion includes at least one of a limiting groove, a flange, or a limiting protrusion. The effect is that the overlap length provides a geometric margin for the support portion to maintain continuous contact with the adjacent spiral ring within the allowable sliding range. When the maximum allowable sliding distance is less than the overlap length, the support portion retains a contact area after moving to the end of the allowable stroke. The limiting groove, flange, or limiting protrusion can directly utilize the local structure of the continuous spiral plate to form a mechanical limit, ensuring that the elastic plate has the sliding freedom required to adapt to deformation without losing radial support due to excessive sliding.

[0015] Preferably, the cut end near the root of the elastic sheet is provided with a crack-stopping part, which is a crack-stopping hole or a rounded transition structure. The effect is that when the elastic sheet is compressed, repeated bending occurs near the root and bending portion. If the cut ends directly with a sharp end, concentrated local stress easily forms at the cut end. By using a crack-stopping hole or a rounded transition, the cut end changes from a sharp bend to a larger radius of curvature, making the stress transition near the root smoother and preserving a continuous material transition zone for repeated deformation of the elastic sheet.

[0016] Preferably, the bending portion has at least one of an indentation, a thinning area, or a pre-bending area, and the support portion has at least one of a rounded edge, a rolled edge, or an enlarged contact portion. The advantages are: the indentation, thinning area, or pre-bending area allows the elastic sheet to bend preferentially at a predetermined position and direction, preventing the bending position from randomly shifting along the elastic sheet; the rounded edge or rolled edge reduces the possibility of the free end contacting adjacent structures with a sharp edge; and the enlarged contact portion increases the contact width or contact area between the support portion and adjacent spiral coils, thereby improving the contact state during repeated relative movements.

[0017] Preferably, a flexible isolation layer is provided on the inner side of the helical elastic support member, and the flexible isolation layer is located between the helical elastic support member and the inner sheath. Its effect is that the flexible isolation layer separates the continuous helical plates and elastic plates from the inner sheath, preventing the rigid support member from directly rubbing against the inner sheath during cable bending, vibration, or pressure; when external impact continues to be transmitted inward, the flexible isolation layer can also provide a second level of buffering through its own compression deformation, preventing the local contact pressure of the helical elastic support member from directly concentrating on the inner sheath.

[0018] Preferably, the continuous spiral blade and the elastic plate are integrally formed from a metal material, engineering plastic, or fiber-reinforced composite material, and the surfaces of the continuous spiral blade and the elastic plate are provided with at least one of an insulating layer, an anti-corrosion layer, or a low-friction coating. The advantages are: the base material of the support member can be selected according to the required elastic recovery capacity, operating temperature, corrosion resistance, and weight requirements; for a metal base, the insulating layer or anti-corrosion layer can reduce the possibility of undesirable electrical contact or environmental corrosion between the metal member and adjacent cable layers; and the low-friction coating, when applied to the sliding contact area, can reduce the frictional resistance generated by repeated relative movement between the support and adjacent spiral coils.

[0019] The beneficial effects of this invention using the above technical solution are as follows: Through the integrated structure of continuous spiral plates and multiple segmented elastic plates, a mechanical protective skeleton is formed on the outer side of the cable, continuous along the spiral direction and capable of independent deformation at local support positions. After a local radial load is applied to the outer sheath, the continuous spiral plates transfer a portion of the load along their own length to adjacent spiral sections. Multiple elastic plates then bear the dispersed load through bending, compression, rotation, or limited slippage, avoiding the concentration of all mechanical action at a single pressure point. A bidirectional constraint is formed between the elastic plates and adjacent spiral rings; the elastic plates provide radial support to the adjacent spiral rings, while the adjacent spiral rings provide reaction force to the elastic plates and limit the deformation stroke, allowing the elastic plates to obtain stable support conditions without relying on independent fasteners. Adjacent elastic plates, segmented by cuts, can adapt to different axial and circumferential stress and bending states of the cable. The continuous spiral plates also allow for relative axial adjustment between adjacent spiral rings. Therefore, the mechanical protective structure improves local load-bearing capacity and elastic recovery while retaining the structural freedom required for cable bending. Forming continuous spiral plates and elastic plates from the same strip blank can also reduce independent support components and their connection processes; pre-tightening, controlled slippage, crack prevention, end wear prevention and flexible isolation structures are used to stabilize the initial support, limit dislocation, improve stress transition at repeated bending positions and protect adjacent sheaths, thereby making the entire spiral elastic support component a sustainable inter-support mechanical protection structure. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the cross-sectional structure of the polyethylene insulated power cable of the present invention.

[0021] Figure 2 This is a three-dimensional structural diagram of the spiral elastic support member of the present invention wound around the outside of the cable.

[0022] Figure 3 This is a cross-sectional view of the spiral elastic support member of the present invention along the cable axis.

[0023] Figure 4 for Figure 3 A magnified schematic diagram of the structure at point A in the middle.

[0024] Figure 5 This is a schematic diagram of the unfolded structure of the strip blank after the incision and crack-stopping part are formed.

[0025] Figure 6 This is a partial structural diagram of the elastic sheet bending and limiting part of the present invention.

[0026] Figure 7 This is a schematic diagram illustrating the process of fabricating the spiral elastic support component and assembling the cable according to the present invention.

[0027] Reference numerals: 1. Conductor; 2. Conductor shielding layer; 3. Polyethylene insulation layer; 4. Insulating shielding layer; 5. Metal shielding layer; 6. Inner sheath; 7. Spiral elastic support component; 71. Continuous spiral plate; 72. Elastic plate; 721. Root; 722. Bending part; 723. Elastic deformation part; 724. Support part; 73. Cut; 74. Crack arresting part; 75. Elastic support space; 76. Limiting part; 8. Flexible isolation layer; 9. Outer sheath. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] like Figures 1 to 7 As shown, a polyethylene insulated power cable includes a cable core, an inner sheath 6, a helical elastic support member 7, and an outer sheath 9. The cable core is used to transmit electrical energy and form a basic insulation structure. The inner sheath 6 is used to cover and protect the outer structure of the cable core. The helical elastic support member 7 is disposed between the inner sheath 6 and the outer sheath 9 and is used to bear the local mechanical load transmitted inward from the outer sheath 9. The outer sheath 9 covers the outside of the helical elastic support member 7 and constitutes the outer protective layer of the cable.

[0030] The cable core includes at least a conductor 1 and a polyethylene insulation layer 3 covering the conductor 1. Depending on the cable's voltage rating and shielding structure, a conductor shielding layer 2 may be provided between the conductor 1 and the polyethylene insulation layer 3. An insulating shielding layer 4 and a metallic shielding layer 5 may be provided outside the polyethylene insulation layer 3. An inner sheath 6 covers the metallic shielding layer 5 or other layered structures located outside the cable core. In this embodiment, the polyethylene insulation layer 3 uses polyethylene insulation material suitable for power cables; however, cross-linked polyethylene insulation material may also be used, provided that electrical insulation and operating temperature requirements are met.

[0031] The helical elastic support member 7 extends spirally around the cable core, and the continuous helical blades 71 form multiple sequentially arranged spiral coils along the cable length. Adjacent spiral coils have a corresponding adjacent relationship in the cable axial direction, and space is reserved between them for the deformation of the elastic blades 72 and the adjustment of cable bending. The continuous helical blades 71 can be directly wound around the outside of the inner sheath 6, or as shown in this embodiment, a flexible isolation layer 8 can be first set on the outside of the inner sheath 6, and then the continuous helical blades 71 can be wound around the outside of the flexible isolation layer 8.

[0032] Combination Figure 2 , Figure 5 and Figure 6As shown, the helical elastic support member 7 includes a continuous helical strip 71 and a plurality of elastic strips 72 integrally connected to the continuous helical strip 71. The plurality of elastic strips 72 are arranged at intervals along the length direction of the continuous helical strip 71, and a cut 73 is formed between adjacent elastic strips 72. The cut 73 extends from one edge of the strip blank towards the main strip area, but does not cut off the main strip area that maintains continuity. Therefore, the sides of adjacent elastic strips 72 are separated from each other, and the root 721 of the elastic strip 72 remains integrally connected to the continuous helical strip 71.

[0033] In one integrated manufacturing embodiment, the helical elastic support member 7 is formed from the same strip blank. The strip blank is divided along its width into a main strip region and an elastic sheet forming region located on one side of the main strip region. The main strip region remains continuous along the length of the strip blank, while the elastic sheet forming region forms multiple slits 73 at intervals along its length. The strip material retained between two adjacent slits 73 constitutes an elastic sheet 72, and the end of each elastic sheet 72 near the main strip region forms a root 721. When the strip blank is subsequently helically wound around the cable core, the continuous main strip region forms a continuous helical sheet 71, and the multiple elastic sheets 72 are repeatedly arranged along the helical direction along with the continuous helical sheet 71.

[0034] like Figure 6 As shown, each elastic sheet 72 includes a bending portion 722, an elastic deformation portion 723, and a support portion 724 sequentially from the root 721 toward the free end. The root 721 is integrally connected to the continuous spiral sheet 71 and is used to provide a fixed end condition for the elastic sheet 72; the bending portion 722 is located near the root 721 and is used to define the starting position of the elastic sheet 72 bending out from the strip plane where the continuous spiral sheet 71 is located toward the support direction; the elastic deformation portion 723 is located between the bending portion 722 and the support portion 724, and generates elastic deformation mainly through bending, compression, or accompanied by small-angle rotation under external load; the support portion 724 is located at the end of the elastic sheet 72 away from the root 721 and is used to establish contact with the spiral coil adjacent along the cable axis.

[0035] The bent portion 722 can be formed by indentation, thinning, or pre-bending. When indentation is used, a local indentation extending along a predetermined bending line can be provided near the root 721, causing the elastic sheet 72 to bend preferentially along that position. When thinning is used, the local thickness at the bending position can be made smaller than the thickness of the adjacent elastic deformation portion 723, thereby reducing the bending resistance at that position. When pre-bending is used, the elastic sheet 72 can obtain an initial bent shape by molding or pre-forming before the strip blank is spirally wound. The above structures are all used to determine the bending position and direction of the elastic sheet 72, and it is not required to fix the specific bending angle without experimental basis.

[0036] The support portion 724 can abut against the inner surface of an adjacent spiral coil or against the edge of an adjacent spiral coil. When the support portion 724 abuts against the inner surface of an adjacent spiral coil, it extends from near the current spiral coil toward the side of the adjacent spiral coil facing the cable core, and is supported by the inner surface of the adjacent spiral coil. When the support portion 724 abuts against the edge, it is located in the support area of ​​the edge of the adjacent spiral coil, and its further movement is restricted by the edge. The specific abutment position can be determined according to the strip width, pitch, and bending shape of the elastic sheet 72.

[0037] The free edge of the support portion 724 can be made into a rounded edge, or it can be formed into a rolled edge or an enlarged contact portion. A rounded edge is used to prevent the sharp free end from directly contacting adjacent spiral coils or adjacent cable layers; a rolled edge forms a gentler contact profile by bending the free end towards itself; an enlarged contact portion increases the width or local area of ​​the support portion 724 along the contact direction, distributing the supporting force over a larger contact area. The above end structures can be used individually or in combination depending on the material and processing method of the strip blank.

[0038] like Figure 3 As shown, after the spiral winding is completed, the root 721 of an elastic sheet 72 remains on the current continuous spiral sheet 71, the elastic deformation portion 723 spans the space between the current spiral coil and the adjacent spiral coil along the cable axis, and the support portion 724 abuts against the adjacent spiral coil. The current spiral coil, the elastic sheet 72, and the adjacent spiral coil thus form a mutually supporting elastic support unit. Multiple elastic support units are repeatedly arranged along the length direction of the continuous spiral sheet 71, so that the spiral elastic support member 7 forms a continuously distributed radial support on the outside of the cable.

[0039] Each elastic plate 72 provides radial support to the adjacent spiral coil, while the adjacent spiral coil simultaneously provides reaction force and deformation stroke limitation to the elastic plate 72. When the current spiral coil is displaced radially inward by external pressure, the root 721 of the elastic plate 72 moves with the current spiral coil, the support portion 724 is constrained by the adjacent spiral coil, and the elastic deformation portion 723 deforms between the two. As the elastic plate 72 deforms, the restoring force generated by the elastic plate 72 forms a reverse support to the compressed spiral coil; the contact limitation of the adjacent spiral coil on the support portion 724 can prevent the elastic plate 72 from opening indefinitely, flipping, or moving away from the predetermined support direction.

[0040] When not subjected to abnormal mechanical loads, the continuous spiral plate 71, the elastic plate 72, and the inner structure form an elastic support space 75 that is repeatedly distributed along the spiral direction. The elastic support space 75 provides deformation stroke for the elastic plate 72 after bending or compression under pressure, and also allows the continuous spiral plate 71 to displace inward within a certain range after being subjected to local radial loads. The elastic support space 75 is not required to form a completely closed cavity in the entire circumferential direction; its main function is to retain the geometric margin required for the elastic plate 72 to undergo recoverable deformation.

[0041] In one pre-tightening embodiment, when the elastic sheet 72 is bent but not yet pressed against the adjacent spiral coil, the root 721 and the support portion 724 have a free state distance along the cable radial direction. This free state distance is greater than the distance along the cable radial direction between the root 721 and the corresponding abutment position of the adjacent spiral coil after the continuous spiral sheet 71 is spirally wound to the assembly position. During the winding process, the adjacent spiral coil presses against the support portion 724, causing the elastic deformation portion 723 to generate initial elastic deformation. After assembly, the support portion 724 continues to press against the adjacent spiral coil, thereby forming an initial support force.

[0042] An axial deformation gap is maintained between adjacent spiral coils along the cable axis. This gap allows for limited axial proximity of adjacent spiral coils at locally compressed locations during stress, and also allows for increased coil spacing on the outer side of the bend and decreased coil spacing on the inner side of the bend when the cable is bent. When the axial deformation gap is combined with the segmented structure of the elastic sheet 72, each elastic sheet 72 can adapt to changes in coil spacing at its respective circumferential position, preventing the continuous spiral sheet 71 from being constructed as a closed rigid sleeve that cannot be adjusted relative to each other.

[0043] In one sliding contact embodiment, the support portion 724 is not fixedly connected to the adjacent spiral coil, and the support portion 724 can slide limitedly along the contact surface of the adjacent spiral coil. When the cable bends, the support portion 724 adjusts the tilt angle of the elastic sheet 72 by changing the contact position; when locally compressed, the limited sliding allows the elastic sheet 72 to release some of the additional torsion caused by the change in the relative position of the spiral coils. The support portion 724 always transmits the supporting force to the adjacent spiral coil through contact, without requiring a rigid fixed connection between the support portion 724 and the adjacent spiral coil.

[0044] A limiting portion 76 can be provided on the continuous spiral blade 71 section forming adjacent spiral coils. The limiting portion 76 is used to limit the maximum sliding distance of the support portion 724 relative to the adjacent spiral coils. The limiting portion 76 can be a limiting groove, a flange, or a limiting protrusion. The limiting groove is used to restrict a local area of ​​the support portion 724 within the allowable movement range of the groove; the flange can be provided on one or both sides of the allowable sliding area of ​​the support portion 724; the limiting protrusion forms the end point of the stroke by contacting the edge of the support portion 724. The specific form of the limiting portion 76 is selected according to the strip material, forming process, and contact direction of the support portion 724.

[0045] The support portion 724 and the adjacent spiral ring have an overlap length in the sliding direction at the initial assembly position. This overlap length refers to the initial overlapping range of the support portion 724 and the adjacent spiral ring in the sliding direction. The maximum sliding distance defined by the limiting portion 76 is less than this overlap length, so that even if the support portion 724 moves to the end of the allowable stroke, a portion of it still remains in contact with the adjacent spiral ring. Thus, the sliding contact provides positional adaptability, and the limiting portion 76 prevents excessive sliding. Together, they ensure that the elastic sheet 72 remains in an effective support position under bending and compression conditions.

[0046] like Figure 5 As shown, a crack-stopping part 74 is provided at one end of the cut 73 near the root 721. The crack-stopping part 74 can be a crack-stopping hole, that is, a hole-like transition is formed at the end of the cut 73 so that the cut does not terminate directly with a sharp crack; the crack-stopping part 74 can also be an arc transition structure, so that the two sides of the cut 73 transition smoothly with an arc near the root 721. Since the elastic sheet 72 mainly undergoes periodic bending near the root 721 and the bending part 722 during repeated compression, the crack-stopping part 74 is used to improve the geometric transition in this area and reduce the stress concentration formed at the end of the sharp cut.

[0047] A flexible insulating layer 8 is disposed inside the helical elastic support member 7, located between the helical elastic support member 7 and the inner sheath 6. The flexible insulating layer 8 can be made of rubber, thermoplastic elastomer, non-woven fabric, or water-blocking buffer tape, and continuously covers or wraps around the outer surface of the inner sheath 6. On the one hand, the flexible insulating layer 8 separates the continuous helical plate 71, the elastic plate 72, and the inner sheath 6, reducing the repeated friction of the rigid support member on the inner sheath 6 during cable bending and vibration; on the other hand, it provides auxiliary buffering through its own compression when external impact continues to be transmitted inward.

[0048] The continuous spiral strip 71 and the elastic strip 72 can be integrally formed from metallic materials, engineering plastics, or fiber-reinforced composite materials. When using metallic materials, stainless steel, spring steel, aluminum alloy, or other metal strips with corresponding elastic recovery capabilities can be selected according to the required elastic limit, operating temperature, and corrosion resistance requirements. When using non-metallic materials, engineering plastics or fiber-reinforced composite materials that meet the requirements for cable operating temperature, flame retardancy, fatigue resistance, damp heat resistance, and aging resistance can be selected. The specific material grade, thickness, and long-term fatigue performance are determined based on the prototype and test results, and are not subject to definitive limitations without experimental basis in this embodiment.

[0049] The surfaces of the continuous spiral blade 71 and the elastic blade 72 may be provided with at least one of an insulating layer, an anti-corrosion layer, or a low-friction coating. The insulating layer is suitable for situations where further electrical isolation between the metal support member and the adjacent conductive structure is required; the anti-corrosion layer is used to improve the surface stability of the support member in a humid or corrosive environment; the low-friction coating may be preferentially provided in the area where the support portion 724 makes sliding contact with the adjacent spiral ring to reduce frictional resistance and surface wear during repeated relative displacement.

[0050] In one unibody metal embodiment, a metal strip with elastic recovery capability is used as the strip blank. Multiple slits 73 are spaced apart along the length of one side of the metal strip, and multiple elastic pieces 72 integrally connected to the main strip area are retained between the slits 73. Subsequently, a bending portion 722 is formed near the root 721, bending each elastic piece 72 towards the same predetermined support direction, so that the elastic deformation portion 723 and the support portion 724 form a spatial shape that can abut against adjacent spiral coils. After the elastic pieces 72 are formed, the main strip area is spirally wound around the inner sheath 6, forming a continuous spiral piece 71 in the main strip area, and each support portion 724 sequentially enters the support position of the adjacent spiral coil.

[0051] In one embodiment with a flexible isolation layer 8, the flexible isolation layer 8 is first laid or wrapped around the outside of the inner sheath 6, and then the helical elastic support member 7 is wound around the outside of the flexible isolation layer 8. The flexible isolation layer 8 covers the outer surface of the inner sheath 6 and forms flexible contact with the continuous helical blade 71 and the elastic blade 72. When the helical elastic support member 7 is subjected to local pressure, the continuous helical blade 71 and the elastic blade 72 first undergo structural deformation, and the remaining load is then transmitted to the inner sheath 6 through the flexible isolation layer 8.

[0052] In one pre-tightened embodiment, before winding, the free-state distance between the root 721 of the elastic sheet 72 and the support 724 along the cable radial direction is greater than the distance along the cable radial direction between the corresponding contact positions of the root 721 and the adjacent spiral coils after winding. During spiral winding, the adjacent spiral coils gradually press against the support 724, causing the elastic sheet 72 to form a pre-tightened deformation. After assembly, the support 724 continues to be in contact with the adjacent spiral coils. When the cable is subjected to small vibrations or slight bending, the elastic sheet 72 still maintains its initial support and does not need to undergo an empty stroke from complete disengagement to re-contact.

[0053] In a controlled sliding embodiment, the support portion 724 slides against the adjacent spiral coil, and a limiting portion 76 is provided in the corresponding section of the continuous spiral blade 71. When the cable bends or is locally compressed, the support portion 724 first slides along the surface of the adjacent spiral coil within an allowable range to accommodate positional changes between adjacent spiral coils; when the support portion 724 reaches the limiting position, the limiting portion 76 prevents it from continuing to move away from the support area. This embodiment is particularly suitable for cable sections that need to retain elastic support under repeated bending conditions.

[0054] In a non-metallic embodiment, the continuous spiral strip 71 and the elastic strip 72 are integrally formed from a strip blank of engineering plastic or fiber-reinforced composite material. A notch 73 separates adjacent elastic strips 72. Even after bending, the elastic strip 72 maintains a mutually supporting relationship with adjacent spiral coils as described above. This non-metallic embodiment reduces the use of continuous metal components and allows for the selection of materials that do not form additional continuous metal loops, depending on the specific electrical structure of the cable. The selected material should maintain sufficient elastic recovery to meet support requirements under predetermined operating temperatures and environmental conditions.

[0055] like Figure 7 As shown, the processing of the helical elastic support member 7 and the cable assembly can be performed in the following sequence: S1, a strip blank is provided, and a main strip region that maintains continuity and an elastic sheet forming region located on one side of the main strip region are defined in the width direction of the strip blank. S2, multiple cuts 73 are formed at intervals along the length direction of the strip blank in the elastic sheet forming region, so that adjacent elastic sheets 72 are separated from each other, while retaining the root 721 of each elastic sheet 72 integrally connected to the main strip region; a crack-stopping hole or a rounded transition structure can be formed at the end of the cut 73 near the root 721. S3, an indentation, thinning area or pre-bending area is formed near the root 721 to form a bending portion 722. S4, multiple elastic sheets 72 are bent relative to the main strip region to form an elastic deformation portion 723 and a support portion 724, and a rounded edge, rolled edge or enlarged contact portion can be formed on the free end of the support portion 724.

[0056] S5, after setting a flexible isolation layer 8 on the outside of the inner sheath 6, the main strip area is spirally wound along the cable axis to form a continuous spiral strip 71. S6, the pitch and bending direction of the elastic strip 72 are controlled so that each support part 724 establishes an abutment relationship with the adjacent spiral rings along the cable axis, and the adjacent spiral rings provide reaction force support and limit the deformation stroke of the elastic strip 72; when a pre-tightening structure is adopted, the initial pre-tightening deformation is formed by the difference between the distance between the root 721 of the elastic strip 72 in the free state and the distance between the support part 724 along the cable radial direction and the corresponding distance in the assembly state.

[0057] S7, an outer sheath 9 is formed on the outside of the spiral elastic support member 7; if necessary, auxiliary isolation or anti-wear material can be set on the outside of the spiral elastic support member 7 before forming the outer sheath 9. During the forming process of the outer sheath 9, the forming pressure of the sheath should not cause the elastic sheet 72 to remain completely flat for a long time, and the elastic support space 75 should be reserved so that the elastic sheet 72 still has a recoverable deformation stroke in the finished cable.

[0058] Working principle:

[0059] Under normal conditions, multiple elastic sheets 72 maintain a predetermined bent shape, and the support portions 724 abut against adjacent spiral coils. Multiple elastic support spaces 75 are formed between the continuous spiral sheets 71 and the inner structure, arranged continuously along the spiral direction. If a pre-tightening structure is used, the elastic sheets 72 are in an initial elastic deformation state and continuously provide support force to adjacent spiral coils. At this time, the continuous spiral sheets 71 maintain the basic outline of the outer side of the cable, and each elastic sheet 72 is segmented from each other through the cuts 73, without the need for synchronous deformation between adjacent elastic sheets 72.

[0060] When a stone, clamp edge, tool, or other foreign object applies localized radial pressure to the outer sheath 9, the outer sheath 9 first transmits the pressure to the corresponding continuous spiral blade 71. The pressure-bearing spiral coil undergoes localized displacement radially inward towards the cable. Since the continuous spiral blade 71 remains continuous along the length of the strip, the bending of the pressure-bearing section affects adjacent sections before and after it, causing a portion of the load to spread along the spiral direction. The multiple elastic plates 72 that support the pressure-bearing spiral coil subsequently bend, compress, rotate, or slip within a limited range, transmitting the applied force to adjacent spiral coils along the cable axial direction.

[0061] After being acted upon by the elastic plate 72, adjacent spiral coils provide a reaction force to the elastic plate 72 and continue to distribute the load through their continuous connection with other sections of the continuous spiral plate 71. The root 721 of the elastic plate 72 is fixed to the current spiral coil, the support portion 724 is constrained by the adjacent spiral coils, and the elastic deformation portion 723 forms a recoverable deformation between the two. After multiple elastic plates 72 are repeatedly arranged along the spiral direction, the local load is borne jointly by the compressed spiral coil, the adjacent elastic plate 72, and the adjacent spiral coils, thereby forming a load transfer path that spans multiple support positions.

[0062] If the support portion 724 adopts a sliding contact, during the compression process, the support portion 724 can produce limited sliding on the surface of the adjacent spiral rings, allowing the elastic sheet 72 to adjust the force angle; when the sliding reaches the maximum distance set by the limiting portion 76, the limiting groove, flange, or limiting protrusion prevents the support portion 724 from continuing to move. Since the maximum sliding distance is less than the overlap length of the initial assembly position, the support portion 724 still maintains contact with the adjacent spiral rings in the limiting position, so the sliding process will not cause the elastic sheet 72 to lose radial support.

[0063] After the external pressure is released, the elastically deformable portion 723, within the elastic deformation range of the material, releases its stored elastic deformation energy and pushes the support portion 724 and the compressed spiral coil back to their initial positions. The continuous spiral blades 71 return to or approach their original contours due to the restoring action of the multiple elastic blades 72, and the elastic support space 75 increases again. In embodiments employing a pre-tightened structure, the elastic blades 72 retain a certain pre-tightened deformation after unloading, allowing the support portion 724 to continue abutting against adjacent spiral coils, thus preserving initial support for subsequent mechanical loads.

[0064] When the cable bends, the spacing between adjacent spiral coils on the outer side of the bend increases relatively, while the spacing between adjacent spiral coils on the inner side of the bend decreases relatively. Since the elastic plates 72 are separated from each other by the notches 73, the elastic plates 72 located at different circumferential positions can individually change the amount of bending and the contact position; when using sliding contact, the support portion 724 can also adjust the contact position along the surface of adjacent spiral coils. The axial deformation gap maintained between adjacent spiral coils further allows for relative movement of the spiral coils, enabling the spiral elastic support member 7 to adjust with the overall bending of the cable, without requiring all elastic plates 72 to maintain the same amount of deformation.

[0065] During the aforementioned process, the continuous spiral plate 71 is responsible for maintaining the continuous load transfer relationship along the cable length direction, while multiple elastic plates 72 are responsible for providing elastic bearing and unloading recovery at various local support positions. Adjacent spiral rings simultaneously bear the reaction force support and stroke limitation of the elastic plates 72. Together, the three form a mutually supporting mechanical protection skeleton, allowing external local mechanical forces to be continuously diffused, segmented elastic bearing, and limited by adjacent spiral rings before being transferred to the inner sheath 6 and cable core.

[0066] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A polyethylene insulated power cable, comprising a cable core and an inner sheath, a helical elastic support member, and an outer sheath disposed from the inside out on the outside of the cable core, wherein the cable core comprises a conductor and a polyethylene insulation layer covering the conductor, characterized in that: The helical elastic support member includes a continuous helical blade extending helically around the cable core and a plurality of elastic plates integrally connected to the continuous helical blade. The continuous helical blade forms a plurality of sequentially arranged helical coils along the cable axial direction. The plurality of elastic plates are spaced apart along the length direction of the continuous helical blade, and a slit is formed between adjacent elastic plates. Each elastic plate includes a root integrally connected to the continuous helical blade and a support portion formed by bending the root relative to the continuous helical blade. The elastic plate extends from the root toward the adjacent helical coil along the cable axial direction. The support portion abuts against the adjacent helical coil so that the elastic plate provides radial support to the adjacent helical coil, and the adjacent helical coil limits the deformation stroke of the elastic plate.

2. The polyethylene insulated power cable according to claim 1, characterized in that, The continuous spiral sheet and the plurality of elastic sheets are formed from the same strip blank. The strip blank includes a main strip region that remains continuous and an elastic sheet forming region located on one side of the main strip region. The elastic sheet forming region is provided with a plurality of cuts spaced apart along the length direction of the strip blank. Each cut extends from one edge of the strip blank toward the main strip region without cutting off the main strip region, so as to form a plurality of elastic sheets that are separated from each other and whose roots are integrally connected to the main strip region.

3. The polyethylene insulated power cable according to claim 2, characterized in that, Each of the elastic sheets includes, in sequence from its root toward its free end, a bending portion, an elastic deformation portion, and a support portion, wherein the support portion abuts against the inner surface or edge of the adjacent spiral ring.

4. The polyethylene insulated power cable according to claim 3, characterized in that, In the free state, the distance between the root and the support along the cable radial direction is greater than the distance between the root and the corresponding abutment position of the adjacent spiral ring along the cable radial direction in the assembled state, so that the elastic sheet is in a pre-tightened state in the assembled state; there is an axial deformation gap between adjacent spiral rings along the cable axial direction.

5. The polyethylene insulated power cable according to claim 3, characterized in that, The support portion slides against the adjacent spiral ring, and the continuous spiral plate is provided with a limiting portion, which is used to limit the sliding distance of the support portion relative to the adjacent spiral ring.

6. The polyethylene insulated power cable according to claim 5, characterized in that, The support portion and the adjacent spiral ring have an overlap length along the sliding direction at the initial assembly position. The maximum sliding distance defined by the limiting portion is less than the overlap length. The limiting portion includes at least one of a limiting groove, a flange, or a limiting protrusion.

7. The polyethylene insulated power cable according to claim 2, characterized in that, The cut is provided with a crack-stopping part at one end near the root of the elastic sheet, and the crack-stopping part is a crack-stopping hole or a rounded transition structure.

8. The polyethylene insulated power cable according to claim 3, characterized in that, The bending portion has at least one of an indentation, a thinning area, or a pre-bending area, and the support portion has at least one of an arc edge, a rolled edge, or an enlarged contact portion.

9. The polyethylene insulated power cable according to claim 1, characterized in that, The inner side of the helical elastic support member is provided with a flexible isolation layer, which is located between the helical elastic support member and the inner sheath.

10. The polyethylene insulated power cable according to claim 1, characterized in that, The continuous spiral blade and the elastic blade are integrally formed from metal material, engineering plastic or fiber-reinforced composite material, and the surfaces of the continuous spiral blade and the elastic blade are provided with at least one of an insulating layer, an anti-corrosion layer or a low-friction coating.

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