A flexible conductor and cable of a hybrid wrapped-braided construction

Abstract

The application discloses a kind of composite winding-braided structure flexible conductor and cable, it is related to special cable technical field.The flexible conductor is formed by 3 to 5 winding conductor units with single-layer bidirectional cross braiding to form braided body;Each winding conductor unit includes central tensile core and winding layer arranged on its outer periphery, and the winding layer is formed by at least 3 metal wires in the same direction with single-layer circumferential non-gap and close winding arrangement.The flexible conductor bears axial tension through the central tensile core, the winding layer maintains the conductive path, and the braided body cross structure disperses the torsional deformation, with high tensile strength, resistance to reciprocating torsion, low resistance change and high flexibility.The cable uses the above flexible conductor as braided layer, and introduces single winding conductor unit into the cable core composite conductor to enhance the twisted conductor, forming a two-stage collaborative load architecture of outer braiding and inner winding, which can meet the stringent requirements of robot joints, aerospace precision equipment and other high-frequency dynamic conditions on cable durability and flexibility.

Description

Technical Field

[0001] This invention relates to the field of special cable technology, and in particular to a flexible conductor and cable with a composite winding-braiding structure. Background Technology

[0002] Currently, in precision equipment that needs to withstand dynamic bending and torsion over long periods, commonly used flexible conductive cables mainly employ conventional braided conductors or traditional wound conductor structures. Conventional braided conductors are typically formed by directly cross-braiding tinned copper wires, and their overall structure does not contain dedicated tensile load-bearing components. This structure results in low axial tensile strength of the conductor. Under repeated bending and oscillation, the braided copper wires are prone to fatigue fracture, leading to loose connections and poor contact in the circuit, making it difficult to guarantee the long-term stability and service life of the conductor.

[0003] To improve overall structural integrity, some conductors are formed using a winding method. Traditional wound conductors are mostly constructed by spirally winding a single strand of wire in a single direction. Compared to braided conductors, their structural consistency is improved, but the conductor's flexibility is insufficient, and the minimum bending radius is relatively large. At the same time, the unidirectional winding method causes the conductor to gradually accumulate internal stress when subjected to repeated torsion, resulting in limited resistance to torsional fatigue and making it unsuitable for high-end applications requiring millions of reciprocating swings and torsional cycles.

[0004] Existing patent documents, such as CN216412697U, propose a multi-unit composite conductor that arranges multiple conductor units side by side. This structure is merely a simple combination of units, and the conductor's flexibility and resistance to torsional cycles are still insufficient. Under long-term dynamic operating conditions, reliability issues such as wire breakage and increased resistance remain.

[0005] In high-end fields such as humanoid robots and smart wearable devices, where the conductors need to withstand both axial tension and millions of high-frequency reciprocating torsion cycles (such as ±180° torsion), the existing pure braided conductors have insufficient tensile strength and are prone to fatigue fracture, while the pure wound conductors have poor flexibility and limited torsional fatigue life. They cannot achieve a balance between high tensile strength and ultra-high torsional fatigue life while maintaining high flexibility and low resistance of the conductor. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to improve the stability and service life of flexible conductors (cables) in application scenarios of high-frequency reciprocating torsion and axial dynamic tension.

[0007] To address the above problems, the present invention proposes the following technical solution: This invention provides a flexible conductor with a composite winding-braiding structure, comprising: A braided body formed by 3 to 5 winding conductor units in a single-layer bidirectional cross-braiding manner, wherein the winding conductor units are divided into two groups that are cross-braided in opposite directions, and the braiding angles of the two groups of winding conductor units are symmetrical with respect to the conductor axis. Each of the aforementioned wound conductor units includes: The central tensile core has a diameter of 0.05mm to 0.20mm. And a winding layer disposed on the periphery of the central tensile core body, the winding layer being composed of at least 3 metal wires wound in the same direction, and adjacent metal wires being arranged side by side in a single layer circumferentially, the diameter of the metal wires being 0.02mm~0.05mm; The braiding angle of the braid is 30°~60°, which is the angle between a single braided wire and the conductor (cable core) axis, and the braiding coverage is 85%~98%.

[0008] Furthermore, the winding pitch of the winding layer is 3 to 8 times the diameter of the metal wire.

[0009] Furthermore, the spiral winding angle of the winding layer is 30°~60°.

[0010] Furthermore, the filling coverage of the metal wires in the winding layer is 70% to 90%.

[0011] Furthermore, the outer diameter of the wound conductor unit is 0.10mm~0.50mm.

[0012] Furthermore, the metal wire is a copper wire, a silver-plated copper wire, or a tin-plated copper wire.

[0013] Furthermore, the central tensile core is made of bulletproof multifilament.

[0014] Furthermore, the starting and ending ends of the winding of the metal wire are fixed to the central tensile core by low-temperature spot welding and / or spot fixing with insulating adhesive.

[0015] The present invention also provides a cable, comprising, from the outside to the inside, a sheath, a first non-woven fabric layer, a braided layer formed by the flexible conductor, a second non-woven fabric layer, and a cable core located within the second non-woven fabric layer; The cable core is composed of multiple sets of twisted pairs and cotton filling material; Each pair of the twisted-pair cables consists of two insulated cores twisted together, each core including an insulation layer and a composite conductor located within the insulation layer.

[0016] Furthermore, the composite conductor includes a stranded conductor and a wound conductor unit wrapped around the outer periphery of the stranded conductor.

[0017] Compared with the prior art, the technical effects achieved by the present invention include: The composite wound-braided flexible conductor provided by this invention integrates a central tensile core and a metal wire winding layer into a wound conductor unit. Three to five wound conductor units are then cross-braided at a symmetrical braiding angle to form a braided structure, creating a synergistic structure where unit load-bearing and braiding dispersion occur. Under axial tensile force, the load is borne by the central tensile core, while the metal wire winding layer maintains the conductive path, giving the conductor both high tensile strength and low resistance. Under reciprocating torsion, the cross-braiding structure of the braided structure disperses torsional deformation along multiple braiding nodes. The metal wire winding layer, arranged in a single-layer, circumferentially gapless, parallel configuration, suppresses wire slippage and loosening, ensuring the conductor maintains a stable rate of resistance change after long-term repeated torsion. Simultaneously, the wire diameter and braided structure give the conductor a small bending radius and high flexibility, enabling it to adapt to continuous dynamic bending in confined spaces.

[0018] The cable provided by this invention, based on the aforementioned flexible conductor as a braided layer, has identical wound conductor units spirally wound within the composite conductor of the cable core, forming a two-stage reinforcement structure with outer braiding and inner winding. The braided layer withstands the torsional and tensile stresses of the entire cable and protects the internal cable core, while the wound conductor units wound around the outer periphery of the stranded conductor provide independent tensile reinforcement for the core wire, ensuring the core wire maintains structural integrity during the dynamic deformation of the entire cable. This cable can be applied in fields with high requirements for dynamic durability, such as humanoid robots and precision aerospace equipment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the cross-sectional structure of the cable provided by the present invention; Figure 2 The diagram shows the structure of a wound conductor unit. In the diagram, the diameter of the central tensile core is d, the diameter of the metal wire is Φ, the winding pitch is P, the winding angle is θ, and the outer diameter of the wound conductor unit is D.

[0021] Figure Labels 1. Sheath; 2. First non-woven fabric layer; 3. Braided layer; 4. Second non-woven fabric layer; 5. Twisted pair; 6. Cotton thread filler; 7. Insulation layer; 8. Composite conductor; 10. Wound conductor unit; 11. Central tensile core; 12. Metal wire. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Similar component reference numerals in the drawings represent similar components. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0024] It should also be understood that the terminology used in the specification of embodiments of the present invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the present invention. As used in the specification of embodiments of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms.

[0025] In applications such as smart wearables and robotic joints that require frequent bending and twisting, conventional braided conductors suffer from low tensile strength and are prone to fatigue and breakage due to the lack of a load-bearing core. Traditional wound conductors, on the other hand, lack flexibility and have limited torsional life. This invention proposes a composite wound-braided flexible conductor, in which a central tensile core 11 is wound with ultra-fine metal wires 12 to form a wound conductor unit 10. Then, 3 to 5 wound conductor units 10 are woven together in a single layer in a bidirectional cross-braid pattern to form a braided body, creating a flexible conductive structure in which the unit load-bearing capacity and the braided structure work together to distribute the load.

[0026] See Figure 2This is a structural schematic diagram of the wound conductor unit 10. In specific implementation, the central tensile core 11 of each wound conductor unit 10 is made of high-strength fiber multifilament, such as bulletproof multifilament. Bulletproof multifilament is usually made of high-performance fibers such as aramid fiber or ultra-high molecular weight polyethylene fiber, and has the characteristics of high breaking strength, low density, resistance to bending fatigue, and good dimensional stability. The diameter d of the central tensile core 11 is 0.05mm to 0.20mm, for example, 0.05mm, 0.08mm, 0.10mm, 0.15mm, or 0.20mm. This central tensile core 11 serves as the main axial load-bearing body within the wound conductor unit 10, distributing the main tensile force to itself and avoiding direct tension on the extremely thin metal wire, thereby significantly improving the overall tensile load-bearing capacity while maintaining the flexibility of the conductor. To further enhance the anti-slip capability between the central tensile core 11 and the metal wire 12, the surface of the central tensile core 11 can be pre-treated with sanding anti-slip treatment, so that the two remain tightly attached during dynamic bending and torsion, preventing internal loosening failure.

[0027] In specific implementation, the winding layer consists of at least three metal wires 12 wound in the same direction around the outer periphery of the central tensile core 11. The metal wires 12 are arranged in a single layer, parallel and tightly without gaps in the same direction, with staggered interlayer arrangement. The central tensile core 11 and the metal wires 12 are tightly bonded without gaps or overhangs. The number of metal wires 12 is related to the diameter of the central tensile core 11 and the diameter of the metal wires 12. Under the premise of satisfying the requirement of a single-layer circumferential gapless arrangement, the number of metal wires 12 can be, for example, three, four, five, or six. When the diameter of the central tensile core 11 is small and the diameter of the metal wires 12 is relatively large, three metal wires are sufficient to form a complete single-layer winding layer. When the diameter of the central tensile core 11 increases or the diameter of the metal wires 12 is thinner, four or more wires can be used to ensure circumferential gapless coverage. Too few metal wires 12 will result in insufficient coverage of the winding layer and insufficient conductive cross-sectional area of ​​the conductor; too many metal wires 12 will increase the thickness of the winding layer and reduce the overall flexibility of the unit. The metal wire 12 can be made of copper wire, silver-plated copper wire, or tin-plated copper wire to meet the requirements of conductivity and oxidation resistance. The diameter Φ of the metal wire 12 is 0.02mm to 0.05mm, for example, 0.02mm, 0.03mm, 0.04mm, or 0.05mm. Using extremely fine metal wire 12 can give the winding layer excellent flexibility. Combined with the single-layer circumferential arrangement, it ensures that the current is evenly distributed among the metal wires 12, reducing the overall DC resistance.

[0028] In practice, the winding pitch P of the winding layer is set according to the diameter Φ of the metal wire 12, preferably 3 to 8 times the diameter Φ of the metal wire 12, for example, 3 times, 4 times, 5 times, 6 times or 8 times. If the pitch P is too small, the stiffness of the winding layer will be too high and the flexibility will be weakened. If the pitch P is too large, the metal wires 12 will easily become loose. Within this range, the structural compactness of the winding layer and the overall bendability of the conductor can be taken into account.

[0029] In practice, the spiral winding angle θ corresponding to the winding pitch P is controlled between 30° and 60°, such as 30°, 40°, 45°, 50° or 60°. This spiral winding angle θ is directly related to the ratio of the winding pitch P to the perimeter of the winding conductor unit 10, affecting the winding density and conductivity stability.

[0030] In specific implementation, the filling coverage of the metal wire 12 in the winding layer is maintained at 70% to 90%, such as 70%, 80%, 85% or 90%, to ensure sufficient metal conductive cross-sectional area while retaining appropriate gaps to absorb bending deformation energy and prevent the metal wire 12 from breaking under repeated strain.

[0031] In specific implementations, the overall outer diameter D of the single wound conductor unit 10, which consists of the central tensile core 11 and the winding layer, should preferably be between 0.10 mm and 0.50 mm, for example, 0.10 mm, 0.20 mm, 0.30 mm, 0.40 mm, or 0.50 mm. This outer diameter D allows the wound conductor unit itself to fit into narrow wiring spaces and provides suitable basic dimensions for subsequent multi-strand braiding.

[0032] In specific implementations, to prevent the metal wire 12 from detaching at its ends, the starting and ending ends of the winding of the metal wire 12 can be fixed to the central tensile core 11 by low-temperature spot welding and / or insulating adhesive spot fixing. Low-temperature spot welding can quickly fuse the ends of extremely fine metal wires, while insulating adhesive spot fixing forms a buffer coating outside the weld point, preventing the weld point from breaking brittlely and enhancing vibration resistance and durability. In some preferred embodiments, the starting and ending ends of the winding of the metal wire 12 are double-fixed to the central tensile core 11 by both low-temperature spot welding and insulating adhesive spot fixing.

[0033] In practice, multiple wound conductor units 10 are further cross-braided to form a braid. The braid consists of 3 to 5 wound conductor units 10, for example, 3, 4, or 5. The choice of the number of wound conductor units 10 is related to the required conductor outer diameter, flexibility requirements, and torsional fatigue life: when the number of units is 3, the braid structure is compact and the outer diameter is small, making it suitable for wiring in confined spaces; when the number of units is 4, the braid achieves a better balance between bending flexibility and torsional fatigue life, and can accurately match the design requirements of various conductor outer diameter specifications; when the number of units is 5, the braid has a larger conductive cross-sectional area and higher current carrying capacity, but the outer diameter increases accordingly and the braiding difficulty increases. If the number of units is less than 3, a complete bidirectional cross-braid structure cannot be formed; if the number of units is more than 5, the braid structure is redundant and the processing efficiency decreases.

[0034] During weaving, the winding conductor unit 10 is divided into two groups that cross in opposite directions. When there are 3 winding conductor units 10, one group has 1 unit and the other group has 2 units, and the two groups are woven in opposite spiral directions. When there are 4 winding conductor units 10, each group has 2 units, and they are woven in opposite spiral directions. When there are 5 winding conductor units 10, one group has 2 units and the other group has 3 units, and the two groups are woven in opposite spiral directions. The weaving angles of the two groups of winding conductor units 10 relative to the conductor axis are symmetrically arranged, that is, the angles between the two groups of winding conductor units 10 and the conductor axis are equal and the spiral directions are opposite. In other embodiments, the conductor can be a set of cable cores.

[0035] The braiding angle is the angle between a single (group) of wound conductor units 10 and the conductor axis. In some embodiments, the braiding angle can be selected from 30° to 60°, such as 30°, 35°, 40°, 45°, 50°, 55°, or 60°. If the angle is too small, the axial stretchability of the braid increases, but the radial constraint weakens, and the braid is prone to loosening; if the angle is too large, the rigidity of the braid increases, but the bending flexibility decreases. Within the range of 30° to 60°, the braid can obtain a soft and flexible structural characteristic while maintaining sufficient radial clamping force. When subjected to torsion, each braid node can undergo slight slippage to release stress.

[0036] In this invention, the coverage of the braided body needs to be controlled between 85% and 98%, such as 85%, 88%, 90%, 92%, 95% or 98%. A higher coverage is beneficial to reduce resistance and enhance external protection, while a moderate coverage retains the softness and flexibility of the braided body and avoids local stress concentration that could lead to the breakage of the winding conductor unit.

[0037] The aforementioned flexible conductor utilizes a central tensile core 11 within the winding conductor unit 10 to bear axial tension, and a metal wire winding layer 12 to maintain the conductive path. Combined with the cross-braided structure of the braided body to disperse torsional deformation, this achieves a synergy of high tensile strength, resistance to reciprocating torsion, low resistance variation, and high flexibility. Based on these properties, this flexible conductor can serve as a torsion-resistant braided layer for cables, providing reliable protection for the internal cable core while withstanding dynamic tensile and torsional stresses.

[0038] In some embodiments, the present invention provides a cable, the cross-sectional structure of which is shown in the figure. Figure 1 The specific structure is as follows: from the outside to the inside, a sheath 1, a first non-woven fabric layer 2, a braided layer 3 composed of the above-mentioned flexible conductor, a second non-woven fabric layer 4, and a cable core are arranged in sequence.

[0039] In practice, the sheath 1 provides the outermost layer of mechanical protection and environmental isolation for the cable. The sheath 1 can be made of thermoplastic polyurethane elastomer, silicone rubber, polyvinyl chloride, or polyester elastomer, with thermoplastic polyurethane elastomer being preferred due to its good flexibility, abrasion resistance, and tear resistance, enabling it to withstand high-frequency dynamic bending conditions. The thickness of the sheath 1 ranges from 0.15mm to 0.50mm, for example, 0.15mm, 0.20mm, 0.30mm, 0.40mm, or 0.50mm, with the specific thickness selected based on the cable's outer diameter and the mechanical strength requirements of the operating environment.

[0040] In specific implementation, the first nonwoven layer 2 is disposed between the sheath 1 and the braided layer 3, and the second nonwoven layer 4 is disposed between the braided layer 3 and the cable core. The first nonwoven layer 2 and the second nonwoven layer 4 serve as isolation and buffer, preventing direct friction between the braided layer 3 and the sheath 1 or the cable core, and providing adequate slippage space during bending to reduce interlayer stress transmission. The nonwoven material can be polyester fiber nonwoven fabric or polypropylene nonwoven fabric, which has the characteristics of good flexibility, low coefficient of friction, and moderate temperature resistance. The thickness of the first nonwoven layer 2 and the second nonwoven layer 4 are independently 0.05mm to 0.15mm, for example, 0.05mm, 0.08mm, 0.10mm, 0.12mm, or 0.15mm.

[0041] As the main load-bearing layer of the cable, braided layer 3 continuously withstands the combined stresses of torsion, tension, and bending under dynamic conditions such as high-frequency reciprocating oscillations with equipment joints, continuous bending, or axial expansion and contraction. In this invention, braided layer 3 is composed of the aforementioned flexible conductor, the main structure of which is a braid formed by multiple wound conductor units through single-layer bidirectional cross-braiding. A suitable margin of movement is maintained between each braiding node. When stress is transmitted to the braided layer, the cross structure gradually disperses the concentrated load along the braiding nodes and transforms it into micro-slippage between the nodes, preventing stress from being concentrated and transmitted to the inner cable core along a single path. Thus, while bearing the main mechanical load, braided layer 3 provides continuous dynamic isolation and buffering for the cable core, protecting the internal twisted pairs and composite conductors from the direct impact of torsional concentration and bending overload.

[0042] In practice, the cable core consists of multiple sets of twisted pairs 5 and cotton thread filler 6. The number of twisted pairs 5 is related to the number of transmission channels, the roundness of the cable core, and space utilization. When multi-channel differential signal transmission is required, 2, 4, or 6 sets of twisted pairs can be selected. Among them, 4 sets of twisted pairs achieve a better balance between transmission capacity, cable core symmetry, and cabling processability, and when combined with cotton thread filler 6, it is easy to obtain a regular circular cross-section. Each set of twisted pairs 5 is formed by twisting two insulated cores together. The twisted pair structure can reduce electromagnetic crosstalk between wire pairs and improve signal transmission stability. The overall outer diameter of the cable core depends on the outer diameter of the twisted pairs 5 and the amount of cotton thread filler, and is usually 1.0mm to 3.0mm, such as 1.0mm, 1.5mm, 2.0mm, 2.5mm, or 3.0mm. The cotton filler 6 fills the gaps between the twisted pairs 5 and is evenly distributed within the cross-section of the cable core. The filling amount is 60% to 90% of the volume of the gap between the cable cores. It maintains the roundness of the cable core and absorbs the deformation energy during bending or compression, preventing the twisted pairs from shifting or rubbing against each other under dynamic working conditions.

[0043] In practice, the insulated conductor consists of an insulation layer 7 and a composite conductor 8 located within the insulation layer 7. The insulation layer 7 can be made of fluoroplastics, polyester elastomers, or cross-linked polyethylene, with fluoroplastics being preferred due to their low dielectric constant, excellent temperature resistance, and superior resistance to bending fatigue, making them suitable for high-frequency signal transmission and dynamic bending scenarios. The thickness of the insulation layer 7 is 0.05 mm to 0.15 mm, for example, 0.05 mm, 0.08 mm, 0.10 mm, 0.12 mm, or 0.15 mm.

[0044] This invention introduces a single wound conductor unit 10 into the interior of the insulated wire core to reinforce the stranded conductor, forming a two-stage cooperative load-bearing structure with outer braiding and inner winding. Specifically, the composite conductor 8 includes a stranded conductor and a wound conductor unit 10 wound in a spiral around the outer periphery of the stranded conductor. The stranded conductor is composed of multiple strands of conductive wire concentrically twisted together. The conductive wire material can be selected from bare copper wire, tin-plated copper wire, silver-plated copper wire, or nickel-plated copper wire, depending on conductivity, oxidation resistance requirements, and ambient temperature. The stranded conductor consists of 7 or 19 strands of single wire, with a single wire diameter of 0.03 mm to 0.08 mm, such as 0.03 mm, 0.05 mm, 0.06 mm, or 0.08 mm. The overall outer diameter of the stranded conductor is 0.10 mm to 0.40 mm. The stranded conductor provides a low-resistance main conductive path for the composite conductor.

[0045] In specific implementation, the wound conductor unit 10 wrapped around the outer periphery of the stranded conductor has the same structure as the wound conductor unit 10 constituting the braid, possessing a winding layer composed of a central tensile core 11 and metal wires 12. The spiral wrapping of this wound conductor unit 10 forms a radial constraint on the stranded conductor, sharing part of the axial tensile force and bending stress on the stranded conductor when the entire cable is subjected to repeated torsion and bending, inhibiting the loosening or fatigue fracture of the stranded copper wires, thereby ensuring that the core wire maintains a stable electrical connection under long-term dynamic conditions. The braided layer and the wound conductor unit 10 inside the core wire constitute a two-level structure of outer braid and inner winding, working together to bear the load, enabling the cable from the system to the core wire to meet the stringent requirements of durability and flexible wiring under high-frequency dynamic conditions, such as humanoid robot joints and aerospace precision equipment.

[0046] Example 1 A composite wound-braided flexible conductor is constructed from four wound conductor units arranged in a single-layer, bidirectional, cross-braided structure. Each wound conductor unit includes: a central tensile core made of elastic multifilament wire with a diameter of 0.10 mm; and a winding layer surrounding the central tensile core, consisting of four tin-plated copper wires with a diameter of 0.03 mm tightly wound in the same direction, with adjacent wires arranged side-by-side in a single-layer, circumferentially seamless manner. The winding pitch of the winding layer is six times the diameter of the wire, the spiral winding angle is 45°, and the fill coverage is 85%. The overall outer diameter of the wound conductor unit is 0.20 mm. The braiding angle of the braid is 45°, the braiding coverage is 92%, and the braiding angles of the two sets of wound conductor units are symmetrically arranged relative to the conductor axis.

[0047] Comparative Example 1 A pure braided conductor is formed by directly cross-braiding a single layer of tin-plated copper wire of the same diameter as in Example 1, with a braiding angle of 45° and a braiding coverage of 92%. It has no central tensile core and no winding conductor units, and the remaining external dimensions are the same as in Example 1.

[0048] Comparative Example 2 A single-strand wound conductor has the same structure as the single-strand wound conductor unit in Example 1: the center is a bulletproof multifilament core, and the outer periphery is tightly wound with 4 tin-plated copper wires. The winding pitch, helical winding angle, and fill coverage are all consistent with Example 1. This single-strand wound conductor is not externally braided.

[0049] Comparative Example 3 A composite wound-braided conductor structure is provided, consisting of four wound conductor units, but with structural parameters deviating from Example 1: a braiding angle of 25° and a braiding coverage of 75%; the winding pitch of a single wound conductor unit is 10 times the diameter of the metal wire. No shaping treatment is performed after braiding. The remaining components are the same as in Example 1.

[0050] Performance testing The following five performance tests were performed on Example 1 and Comparative Examples 1-3. The outer diameter of the conductors of each sample was the same, and the copper wire was made of tin-plated copper. The test results are shown in Table 1.

[0051] Tensile strength test: A copper wire elongation tester was used to stretch the conductor at a constant speed, record the maximum tensile force when the conductor broke, and calculate the tensile strength.

[0052] Torsion cycle test: Using a cable vertical torsion tester, the cable is continuously torsiond 1 million times under the conditions of ambient temperature 23℃±2℃, torsion angle ±180°, and frequency 2Hz. The DC resistance before and after torsion is tested, and the resistance change rate is calculated.

[0053] Bending flexibility test: The minimum bending radius that the conductor can achieve is tested using a bending tester.

[0054] DC resistance test: The initial DC resistance of the conductor is tested using a DC resistance tester under a constant temperature of 20℃.

[0055] Bending durability test: Using the minimum bending radius as the bending radius, perform 100,000 reciprocating bends and observe the surface condition of the conductor.

[0056] Table 1 Performance test results of each embodiment and comparative example As shown in Table 1, Example 1 is superior to the three comparative examples in terms of tensile strength, torsional resistance, flexibility, electrical conductivity and bending durability.

[0057] Compared to Comparative Example 1, Example 1 adds a central tensile core and a winding layer structure. Comparative Example 1 is a pure braided conductor with copper wires directly cross-woven, without any load-bearing core. The tensile force is entirely borne by the copper wires, resulting in a tensile strength of only 152 MPa. In the torsion test, the copper wires directly bear alternating stress, and after 1 million cycles, multiple wires break, with a resistance change rate as high as 18.7%. Example 1 introduces bulletproof multifilament as the central tensile core, where the tensile force is mainly borne by the core, and the copper wires only maintain the conductive path, increasing the tensile strength to 218 MPa. The single-layer circumferentially tight arrangement of the winding layer and the cross-dispersion of the braid work synergistically to reduce the resistance change rate after torsion to 3.2%. At the same time, the combination of ultra-fine copper wires and a soft braid reduces the bending radius of Example 1 from 3.8 mm to 2.5 mm, significantly improving flexibility.

[0058] Compared to Comparative Example 2, Example 1 incorporates a multi-unit braided structure. Comparative Example 2 uses a single wound conductor unit. Although the tensile strength reaches 205 MPa due to the core, similar to Example 1, it lacks a stress dispersion mechanism within the braided structure. During torsion, stress concentrates along the helical direction of the single unit, resulting in a resistance change rate of 11.5% after 1 million torsion cycles. Furthermore, the single unit has a large outer diameter, lacks a loose braided structure, and has a bending radius of 5.2 mm, exhibiting poor flexibility. In Example 1, by cross-braiding four wound conductor units, the braided nodes can slightly slide to release torsional deformation, significantly improving torsional resistance. Simultaneously, the overall flexibility of the braided structure is superior to that of a single large-diameter unit.

[0059] Compared to Comparative Example 3, Example 3, although also constructed from wound conductor units, has a smaller weaving angle of 25°, a lower coverage of 75%, a looser braided structure, and a larger winding pitch resulting in less dense copper wire arrangement. Therefore, its performance is inferior to Example 1 in all aspects. Specifically, the tensile strength decreased to 186 MPa, the rate of change in resistance after torsion increased to 9.8%, and the braided layer became loose after bending. This indicates that the weaving angle, coverage, and winding pitch must be within the preferred range of this invention to achieve the synergistic effect between the wound units and the braided structure.

[0060] Example 2 A torsion-resistant composite cable comprises, from the outside to the inside: a sheath made of thermoplastic polyurethane elastomer with a thickness of 0.30 mm; a first nonwoven fabric layer made of polyester fiber nonwoven fabric with a thickness of 0.08 mm; a braided layer composed of the flexible conductor described in Example 1; a second nonwoven fabric layer with the same material and thickness as the first nonwoven fabric layer; and a cable core.

[0061] The cable core consists of four sets of twisted pairs and cotton filler. The outer diameter of the cable core is 2.0 mm, and the cotton filler volume is 80% of the gap volume between the cable cores. Each set of twisted pairs is formed by twisting two insulated cores together. The insulated cores include a fluoroplastic insulation layer (0.10 mm thick) and a composite conductor located within the insulation layer. The composite conductor includes a stranded conductor and a spiral conductor unit wound around the outer circumference of the stranded conductor. The stranded conductor is composed of seven tinned copper wires with a diameter of 0.05 mm twisted concentrically, with an outer diameter of 0.15 mm. The spiral conductor unit wound around the outer circumference of the stranded conductor has the same structure as the spiral conductor unit in Example 1.

[0062] Comparative Example 4 A cable, whose sheath, first non-woven fabric layer, braided layer, second non-woven fabric layer, number and arrangement of twisted pairs in the cable core, and insulation layer are all the same as in Example 2. The difference is that the composite conductor is composed only of stranded conductors, the specifications of which are the same as in Example 2, but conductor units are not wrapped around the outer periphery of the stranded conductors.

[0063] Comparative Example 5 A cable whose sheath, first non-woven layer, second non-woven layer, and core structure are the same as those in Example 2. The difference is that the braided layer is made of conventional tin-plated copper wire directly cross-braided, the diameter of the copper wire is the same as that of the copper wire used to wind the conductor unit in Example 2, the braiding angle is 45°, and the braiding coverage is 92%. There is no winding conductor unit in the braided layer, that is, the copper wire is not pre-wound to the central tensile core before braiding, but is directly braided from bare copper wire.

[0064] The following performance tests were conducted on Example 2 and Comparative Examples 4-5, and the test results are shown in Table 2.

[0065] Cable torsion life test: Fix both ends of the cable to a cable torsion testing machine and continuously torsion it at a room temperature of 23℃±2℃, a torsion angle of ±180°, and a frequency of 2Hz. Monitor the resistance of each pair of twisted conductors in the cable. Failure is defined as a change in resistance of any pair of twisted conductors exceeding 10%, and the number of torsions at which failure is reached is recorded.

[0066] Cable bending life test: The cable is installed on a bending tester and bent repeatedly at a frequency of 1Hz, with a bending radius of 8 times the cable's outer diameter. Failure is defined as a change in resistance of more than 10% in any pair of twisted-pair conductors or the appearance of a through-crack in the sheath. The number of bends at which failure is reached is recorded.

[0067] Dynamic tensile bending test of the entire cable: One end of the cable is fixed, and a constant tensile force of 1N is applied to the other end. The cable is then bent back and forth at ±90° along a 20mm diameter mandrel at a frequency of 1Hz. After 500,000 cycles, the resistance change rate of each pair of twisted-pair conductors and the appearance of the cable are checked.

[0068] Table 2 Cable performance test results As shown in Table 2, Example 2 is significantly better than Comparative Example 4 and Comparative Example 5 in terms of overall cable torsional life, bending life, and dynamic tensile bending durability.

[0069] Compared to Comparative Example 4, Example 2 has the same braided layer, sheath, non-woven fabric layer, and core layout. The only difference is that Comparative Example 4 did not use spiral winding conductor units to reinforce the stranded conductors in its composite conductor. Comparative Example 4 failed after approximately 680,000 torsion tests and approximately 450,000 bending tests, with individual wire pairs showing broken wires and a resistance change rate of 12%–18% after 500,000 dynamic tensile bending tests. Example 2, under the same test conditions, did not fail after more than 1 million torsion tests and more than 800,000 bending tests. After 500,000 dynamic tensile bending tests, the resistance change rate was controlled within 4%, and the sheath remained intact. This indicates that relying solely on the external braided layer to protect the core, without the radial constraint and axial reinforcement of the stranded conductors from the internal winding conductor units, will cause the stranded copper wires to gradually loosen, shift, and eventually fatigue fracture under high-frequency dynamic deformation of the entire cable due to the lack of internal support. When a winding conductor unit is introduced into the core wire, the unit forms a continuous reinforcing wrapping layer around the stranded conductor, which inhibits the loosening of the stranded wires from the inside of the core wire and forms a synergistic load-bearing structure with the outer braided layer, thus greatly improving the dynamic durability of the entire cable.

[0070] Compared to Comparative Example 5, Example 2 has the same sheath, non-woven fabric layer, and cable core structure; the only difference lies in the construction of the braided layer. In Comparative Example 5, the braided layer is formed by directly cross-braiding bare copper wires. Without a central tensile core for support, when the entire cable is subjected to torsion, the copper wires at the braiding intersections directly bear alternating friction and bending stress, resulting in conductor failure after approximately 550,000 cycles. After 500,000 cycles of dynamic tensile bending, individual wire pairs break, the resistance change rate reaches 15%–22%, and the braided layer itself also shows localized fractures. In Example 2, the braided layer is woven from wound conductor units. Each unit has a central tensile core for load bearing, and the stress between braiding nodes is distributed through the core within the unit. The braided layer itself maintains structural integrity under long-term dynamic loads while providing continuous and effective protection for the internal cable core. The comparison shows that replacing bare copper wires with wound conductor units as the braiding element is key to achieving high torsional and bending durability in the braided layer.

[0071] The test results of Comparative Examples 4 and 5 show that: Comparative Example 5 lacks core reinforcement with wound conductor units in the braided layer, resulting in the shortest torsional life (approximately 550,000 cycles); Comparative Example 4 lacks reinforcement with wound conductor units within the core wire, and although its torsional life is slightly higher than Comparative Example 5 (approximately 680,000 cycles), it is still far lower than Example 2 (>1 million cycles). Only when both the outer braided layer and the inner core wire employ wound conductor units for reinforcement, can the two-stage structure of outer braid and inner winding work together to bear the load, enabling the cable to achieve a torsional life of millions of cycles and excellent dynamic bending reliability.

[0072] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0073] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A flexible conductor with a composite winding-braiding structure, characterized in that, include: A braided body formed by 3 to 5 winding conductor units in a single-layer bidirectional cross-braiding manner, wherein the winding conductor units are divided into two groups that are cross-braided in opposite directions, and the braiding angles of the two groups of winding conductor units are symmetrical with respect to the conductor axis. Each of the aforementioned wound conductor units includes: The central tensile core has a diameter of 0.05mm to 0.20mm. And a winding layer disposed on the periphery of the central tensile core body, the winding layer being composed of at least 3 metal wires wound in the same direction, and adjacent metal wires being arranged side by side in a single layer circumferentially, the diameter of the metal wires being 0.02mm~0.05mm; The weaving angle of the braid is 30°~60°, and the weaving coverage is 85%~98%.

2. The flexible conductor according to claim 1, characterized in that, The winding pitch of the winding layer is 3 to 8 times the diameter of the metal wire.

3. The flexible conductor according to claim 1, characterized in that, The spiral winding angle of the winding layer is 30°~60°.

4. The flexible conductor according to claim 1, characterized in that, The filling coverage of the metal wires in the winding layer is 70% to 90%.

5. The flexible conductor according to claim 1, characterized in that, The outer diameter of the wound conductor unit is 0.10mm~0.50mm.

6. The flexible conductor according to claim 1, characterized in that, The metal wire is copper wire, silver-plated copper wire, or tin-plated copper wire.

7. The flexible conductor according to claim 1, characterized in that, The central tensile core is made of bulletproof multifilament.

8. The flexible conductor according to claim 1, characterized in that, The starting and ending ends of the winding of the metal wire are fixed to the central tensile core by low-temperature spot welding and / or spot fixing with insulating adhesive.

9. A cable, characterized in that, It includes, from the outside to the inside, a sheath, a first non-woven fabric layer, a braided layer formed by a flexible conductor as described in any one of claims 1-8, a second non-woven fabric layer, and a cable core located within the second non-woven fabric layer; The cable core is composed of multiple sets of twisted pairs and cotton filling material; Each pair of the twisted-pair cables consists of two insulated cores twisted together, each core including an insulation layer and a composite conductor located within the insulation layer.

10. The cable according to claim 9, characterized in that, The composite conductor includes a stranded conductor and a wound conductor unit wrapped around the outer periphery of the stranded conductor.

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