Lightweight umbilical cable

Abstract

The invention provides a light-weight umbilical cable which comprises a total cable core, an inner protective layer wrapping the total cable core and an armor layer wrapping the inner protective layer, and the armor layer comprises a non-metal armor layer close to one side of the inner protective layer and a metal armor layer far away from one side of the inner protective layer. According to the light-weight umbilical cable, the low-density nonmetal armor layer is adopted to replace part of the metal armor layer, so that the overall weight of the light-weight umbilical cable is remarkably reduced, the mechanical strength of a traditional metal armor is reserved, the water depth application limitation of the traditional metal armor cable is broken through, and a more reliable cable body supporting scheme is provided for deep sea operation.

Description

Technical Field

[0001] This invention relates to the field of submarine cable technology, and specifically to a lightweight umbilical cable. Background Technology

[0002] As deep-sea exploration and resource development advances to depths exceeding 6,000 meters, equipment such as remotely operated vehicles (ROVs) face severe challenges in extreme depth environments. The umbilical cable, as a critical connection and power supply component, typically uses high-strength steel wire as the load-bearing unit to ensure sufficient mechanical strength.

[0003] However, due to the high wire density used in the armor layer of existing umbilical cables, the proportion of the cable's own weight to the safe working load increases significantly with increasing operating water depth. In ultra-deep water conditions, the excessive weight of traditional steel wire reinforced umbilical cables leads to a sharp decrease in the effective load ratio, severely restricting the operational capabilities and functional expansion of underwater equipment in extremely deep waters.

[0004] Specifically, the existing technology has the following problems: (1) In ultra-deep water (>6000 meters) environments, the self-weight of traditional steel wire reinforced umbilical cables is too high, the effective load ratio is significantly reduced, and the load capacity and operating efficiency of underwater equipment are directly affected; (2) As the water depth increases, the proportion of safe working load consumed by the cable body self-weight is increasing, the weight of the operating tools that can be carried is severely limited, and the diversity of equipment functions is restricted; (3) The excessive self-weight of the cable body weakens the underwater equipment's ability to resist ocean current disturbances, affecting its positioning accuracy and operating stability in deep water environments.

[0005] In view of this, it is necessary to improve the existing lightweight umbilical cable to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a lightweight umbilical cable to solve the problem that existing umbilical cables are too heavy and therefore have poor performance in ultra-deep water environments.

[0007] To achieve the above objectives, the lightweight umbilical cable of the present invention includes a main cable core, an inner sheath covering the main cable core, and an armor layer covering the inner sheath. The armor layer includes a non-metallic armor layer on the side closer to the inner sheath and a metallic armor layer on the side farther from the inner sheath.

[0008] As a further improvement of the present invention, the non-metallic armor layer is formed by twisting together multiple non-metallic wires or non-metallic strips, and the metallic armor layer is formed by twisting together multiple metal wires or metal strips.

[0009] As a further improvement of the present invention, the non-metallic wire or non-metallic strip is made of fiber-reinforced composite material and is covered with nylon material on the outside, and the metallic wire or metallic strip is made of galvanized aluminum alloy steel wire and coated with anti-corrosion grease.

[0010] As a further improvement of the present invention, the twisting directions of the metal armor layer and the non-metal armor are opposite.

[0011] As a further improvement of the present invention, the armor layer further includes at least one composite armor layer disposed between the non-metallic armor layer and the metallic armor layer, the composite armor layer being formed by alternating twisting of metal wires and non-metallic wires.

[0012] As a further improvement of the present invention, the composite armor layer is one layer, and the composite armor layer is twisted in the same direction as the non-metallic armor layer and in the opposite direction to the metallic armor layer.

[0013] As a further improvement of the present invention, the main cable core includes a power unit, a control unit, and an optical fiber unit.

[0014] As a further improvement of the present invention, the control unit and the optical fiber unit are twisted together, and the control unit and the optical fiber unit are covered with an inner shielding layer to form an inner cable core, the inner cable core being located in the middle of the total cable core.

[0015] As a further improvement of the present invention, the number of power units is multiple, the total cable core includes multiple ground wire units, and the multiple power units and ground wire units are uniformly twisted around the inner shielding layer.

[0016] As a further improvement of the present invention, the main cable core further includes an outer shielding layer, the power unit, the control unit and the optical fiber unit are housed in the outer shielding layer, and the outer shielding layer is filled with water-blocking adhesive.

[0017] The beneficial effects of this invention are as follows: The lightweight umbilical cable of this invention uses a low-density non-metallic armor layer to replace part of the metallic armor layer, which significantly reduces the overall weight of the lightweight umbilical cable while retaining the mechanical strength of traditional metallic armor. This breaks through the water depth application limitations of traditional metallic armored cables and provides a more reliable cable support solution for deep-sea operations. By setting a composite structure of metallic and non-metallic armor layers as the load-bearing layer, not only is the weight of the lightweight umbilical cable itself reduced, but it also maintains a high mechanical strength compared to non-metallic armored umbilical cables. This solves the problems of weak mechanical strength such as lateral pressure resistance of traditional metallic armored umbilical cables in ultra-deep water applications and traditional non-metallic armored umbilical cables. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the lightweight umbilical cable of the present invention; Figure 2 It is a fracture tensile test curve; Figure 3 It is a fatigue test curve under alternating load; Figure 4 This is a schematic diagram showing the wear and tear inside the armor layer.

[0019] Reference numerals: 100, Lightweight umbilical cable; 1, Main cable core; 11, Power unit; 12, Control unit; 13, Fiber optic unit; 14, Inner shielding layer; 15, Grounding unit; 16, Outer shielding layer; 2, Inner sheath; 3, Armoring layer; 31, Non-metallic armoring layer; 311, Non-metallic wire; 32, Metallic armoring layer; 321, Metallic wire; 33, Composite armoring layer. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] like Figures 1 to 4 As shown, the lightweight umbilical cable 100 of the present invention includes a main cable core 1, an inner sheath 2 covering the main cable core 1, and an armor layer 3 covering the inner sheath 2. The armor layer 3 includes a non-metallic armor layer 31 on the side close to the inner sheath 2 and a metallic armor layer 32 on the side away from the inner sheath 2.

[0024] The non-metallic armor layer 31 is formed by twisting together multiple non-metallic wires 311 or non-metallic strips, and the metallic armor layer 32 is formed by twisting together multiple metal wires 321 or metal strips. In this embodiment, non-metallic wires 311 and metal wires 321 are used.

[0025] The lightweight umbilical cable 100 of the present invention was compared with a metal (steel wire armored) umbilical cable of the same structure and size. The results are shown in the table below:

[0026] As can be seen, placing lower-density, high-performance non-metallic materials in the inner layer, directly replacing part of the traditional metal wires, is the core of achieving lightweighting. This design reduces the unit weight of the lightweight umbilical cable 100 by 30.5% in air and 37.29% in seawater, and this weight reduction directly translates into improved performance. The reduced weight of the lightweight umbilical cable 100 means that, under the same safe working load, it can carry heavier tools or lower equipment to deeper waters. Without additional weight load, the static operating depth of the lightweight umbilical cable 100 increases from 5826 meters to 7432 meters, an increase of 27.57%.

[0027] In addition to bearing the weight of the ROV and its own weight, umbilical cables are subjected to environmental loads such as waves and ocean currents, as well as dynamic impact loads from the heave and sway of the mother ship during use. Long-term use will lead to fatigue and wear. The main failure modes of umbilical cables during use are tensile overload fracture, fatigue damage, and frictional wear. To verify the mechanical properties and long-term reliability of the lightweight umbilical cable 100 of this invention, fracture tensile tests, alternating load fatigue tests, and tensile bending load fatigue tests were conducted based on the main failure modes.

[0028] Tensile fracture test: Tensile properties are crucial for ensuring the safe ROV recovery and deployment of umbilical cables. Because the armor layer 3 of the lightweight umbilical cable 100 is composed of multiple materials, complex contact, friction, and slippage effects exist within its internal units under different loads, resulting in an overall nonlinear characteristic. Following the Cigre TB 623 tensile testing method, a horizontal tensile testing machine was used to conduct fracture tensile tests on the sample cable. The tests were conducted at loads of 400 kN and 650 kN to verify whether creep fracture would occur in the non-metallic materials. The fracture tensile test results are shown below. Figure 2 .

[0029] like Figure 2 As shown, the lightweight umbilical cable 100 ultimately fractured at the root of the terminal load-bearing device, manifested as the breakage of some non-metallic wires 311 and metallic wires 321. The breaking tensile force was 863.8 kN, which is only 0.18% different from the theoretically calculated value of 880 kN. This confirms that the lightweight umbilical cable 100 does not experience partial material fracture due to the use of two materials with different elongations and strengths, namely non-metallic wires 311 and metallic wires 321, thus preventing the actual fracture load from being lower than the theoretical fracture load.

[0030] Alternating load fatigue test: During offshore operations, waves and the heave / sinking motion of the mother ship impose impact loads on the umbilical cable. Long-term, repeated use will cause fatigue damage to the steel wires, copper conductors, and other metal components in the umbilical cable, ultimately compromising its structural integrity. Moreover, the more severe the impact, the greater the stress amplitude and the more significant the reduction in lifespan. This means that even if the tensile force on the umbilical cable is less than the safe working load, it may still break. Therefore, alternating load fatigue performance is one of the key performance characteristics for the long-term use of the umbilical cable. Following the fracture tensile test method, the maximum alternating load was selected as the safe working load of 220kN, and the minimum load was selected as 50% of the safe working load, i.e., 110kN. Considering the actual service life of the lightweight umbilical cable 100, a total of 2000 cycles were conducted in this test. The test curve is shown below. Figure 3 As shown.

[0031] like Figure 3 It can be seen that after 2000 alternating load fatigue tests, the photoelectric performance of the main cable core 1 was normal, the surface condition of the load-bearing layer was good, and no twisting or deformation was observed. After the alternating load fatigue test, a fracture tensile test was conducted, and the final breaking force of the umbilical cable reached 828.9 kN, a decrease of 4.0% compared to the umbilical cable that did not undergo the alternating load fatigue test. However, considering that the umbilical cable is already designed for a service life of several thousand cycles, the fact that the lightweight umbilical cable still has high strength after 2000 fatigue tests indicates that it performs well in the face of long-term impact loads.

[0032] Tension bending load fatigue test: The lightweight umbilical cable 100 is wound on a winch. During each deployment and retrieval, the cable is subjected to bending under tension at the winch, A-frame, and steering wheel, resulting in compression and wear between the load-bearing units. These factors damage both the metal wires 321 and the non-metal wires 311 of the lightweight umbilical cable 100. Therefore, the tensile bending load fatigue performance of the lightweight umbilical cable 100 is a key performance characteristic for long-term use. Using a load fatigue testing machine, a safe working load of 220kN was applied to the lightweight umbilical cable 100. Then, a reciprocating winding motion was simulated on a reel with a bending radius of 700mm. The test was set to 2000 cycles. After the test, the sample cable was dissected to observe the wear of the metal wires 321 and the non-metal wires 311. The wear conditions are as follows: Figure 4 As shown.

[0033] The test results showed that the umbilical cable surface remained intact after the test, without any twisting or deformation. Dissection revealed interlayer wear marks on the surfaces of both non-metallic wire 311 and metallic wire 321, with similar wear depths for both materials. The nylon wear-resistant layer on the surface of non-metallic wire 311 was not completely worn through. The load-bearing structure between non-metallic wire 311 and metallic wire 321 remained stable, and non-metallic wire 311 did not fail under compression and bending. This indicates that the lightweight umbilical cable 100 exhibits high reliability and stability during repeated winding processes.

[0034] In addition, the lightweight umbilical cable 100 has a 20.0% lower bending stiffness, which results in better compliance in dynamic applications. The non-metallic armor layer 31 contributes to better flexibility, making the cable easier to bend under the action of waves and reducing internal stress.

[0035] The non-metallic armor layer 31 plays a crucial buffering role on the inner side. The outer hard metal armor layer 32 resists external impacts and abrasion, while the inner non-metallic layer buffers the direct compression of the outer metal wires 321 on the inner main cable core 1, optimizes the overall stress distribution, and protects the core functional unit.

[0036] Although the non-metallic armor layer 31 is lightweight, its mechanical strength is relatively weak, especially in terms of resistance to lateral pressure and dynamic load. By setting a metallic armor layer 32 on the outer layer, the mechanical strength of the lightweight umbilical cable 100 is significantly improved, solving the strength defects of all non-metallic armor.

[0037] The lightweight umbilical cable 100 of the present invention features a non-metallic armor layer 31 and a metallic armor layer 32, which achieve a balance between weight reduction and reinforcement, while taking into account high strength, excellent flexibility and high durability. It successfully breaks through the limits of traditional umbilical cables in deep water applications and provides a reliable technical solution for ultra-deep water scientific research and operations.

[0038] In this embodiment, the non-metallic wire 311 or non-metallic strip is made of fiber-reinforced composite material and coated with nylon material. The non-metallic wire 311 exhibits significantly superior overall performance compared to traditional metallic materials, with a density controlled below 1.4 g / cm³, a tensile strength exceeding 1600 MPa, and excellent corrosion resistance. It should be noted that the non-metallic wire 311 or non-metallic strip is not limited to a single material; it can also be a composite of multiple materials. The non-metallic armor layer 31 can also be formed by twisting together non-metallic wires 311 of different materials.

[0039] In this embodiment, the metal wire 321 or non-metallic strip is made of galvanized aluminum alloy steel wire and coated with anti-corrosion grease. As the outermost protective structure, the double metal coating (zinc-aluminum composite) significantly improves wear resistance and corrosion resistance, effectively resisting mechanical friction and external impact in the marine environment. This provides a reliable protective barrier for the internal optical and electrical units, ensuring long-term stable operation under complex working conditions, thereby greatly improving the service life and reliability of the lightweight umbilical cable 100 in the deep-sea environment.

[0040] In this embodiment, the metal armor layer 32 and the non-metal armor are twisted in opposite directions. This design is to achieve torsional balance.

[0041] The armor layer 3 further includes at least one composite armor layer 33 disposed between the non-metallic armor layer 31 and the metallic armor layer 32. The composite armor layer 33 is formed by alternating twisting of metal wires 321 and non-metallic wires 311. The composite armor layer 33 can effectively buffer the direct compression of the outer metal wires 321 on the inner non-metallic wires 311, thereby optimizing the overall stress distribution while ensuring mechanical strength.

[0042] In this embodiment, the composite armor layer 33 is a single layer, and the composite armor layer 33 is twisted in the same direction as the non-metallic armor layer 31, but in the opposite direction to the metallic armor layer 32. The composite armor layer 33 has the same number of non-metallic wires 311 and metallic wires 321.

[0043] In other embodiments, the composite armor layer 33 may also be multi-layered, and the materials used for the metal wire 321 and non-metal wire 311 of the multi-layered composite armor layer 33 may be different. By changing the materials, the overall density of the inner composite armor layer 33 may be greater or the overall density of the outer composite armor layer 33 may be greater.

[0044] In this embodiment, the main cable core 1 includes a power unit 11, a control unit 12, and an optical fiber unit 13. The power unit 11 supplies power to the remotely operated underwater vehicle (ROV) or other deep-sea observation equipment, serving as the energy source for equipment operation. The control unit 12 transmits control signals and commands, enabling precise control of various actions of the underwater equipment, and receiving status signals from some sensors. The optical fiber unit 13 enables high-speed, high-capacity bidirectional data communication between the surface vessel and the underwater equipment.

[0045] The power unit 11 and the control unit 12 are composed of conductors and insulating sheaths, and the optical fiber unit 13 is composed of optical fiber, stainless steel tube and fiber optic paste.

[0046] The control unit 12 and the optical fiber unit 13 are twisted together, and the control unit 12 and the optical fiber unit 13 are covered by an inner shielding layer 14 to form an inner cable core, which is located in the middle of the total cable core 1. The inner shielding layer 14 is a wrapped metal composite tape, and different shielding materials can be flexibly selected according to the needs of the actual application scenario. For example, bare copper wire braiding or wrapping is used in high conductivity environments to obtain the best electromagnetic shielding effect. In high corrosion-resistant environments, tin-plated copper material is used to enhance its corrosion resistance while ensuring good conductivity. The inner shielding layer 14 mainly plays the roles of electromagnetic shielding, binding and shaping, and radial blocking.

[0047] The control unit 12 and the optical fiber unit 13 are twisted together and placed in the middle of the main cable core 1 and wrapped with an inner shielding layer 14. This design firstly significantly improves signal integrity through space optimization and electromagnetic shielding: the core signal / communication unit is tightly twisted together and a protective barrier is formed by the inner shielding layer 14, which effectively resists electromagnetic interference generated by the external power unit 11 and ensures the stability and reliability of control commands and high-speed data transmission.

[0048] The power units 11 are multiple, and the main cable core 1 also includes multiple ground wire units 15, with the power units 11 and ground wire units 15 uniformly twisted around the inner shielding layer 14. Each ground wire unit 15 consists of a conductor and a semi-conductive sheath, providing a safe grounding path for the power transmission system of the lightweight umbilical cable 100, ensuring the safety of equipment and personnel. The ground wire units 15 are cleverly placed in the gaps created during the twisting of the power units 11, closely adjacent to them. This design not only optimizes the space utilization of the main cable core 1 but also enables it to form an effective electrical connection with the power units 11.

[0049] The main cable core 1 also includes an outer shielding layer 16, within which the power unit 11, control unit 12, and optical fiber unit 13 are housed. The outer shielding layer 16 is filled with water-blocking adhesive. The outer shielding layer 16 is a wrapped metal composite tape, and different shielding materials can be flexibly selected according to the needs of the actual application scenario. For example, bare copper wire braiding or wrapping can be used in highly conductive environments to achieve the best electromagnetic shielding effect. In highly corrosive environments, tin-plated copper material can be used to enhance corrosion resistance while ensuring good conductivity.

[0050] The inner sheath 2 is an extruded plastic layer. On the one hand, it provides mechanical buffer for the main cable core 1, which is formed by twisting together the power unit 11, control unit 12, optical fiber unit 13, ground wire unit 15, etc., to reduce the damage to the internal components caused by cable bending. On the other hand, it can prevent seawater penetration and facilitate watertight treatment at the underwater terminal.

[0051] The spiral twisting pattern of each wire core within the inner sheath 2 can be customized according to the photoelectric transmission requirements of underwater equipment. The twisting gap between the control unit 12 and the optical fiber unit 13 can be supplemented with a ground wire or a drain wire, and the semi-conductive sheath of the ground wire unit 15 can be replaced with an insulating sheath.

[0052] The lightweight umbilical cable 100 of this invention uses a low-density non-metallic armor layer 31 to replace part of the metallic armor layer 32, which significantly reduces the overall weight of the lightweight umbilical cable 100 while retaining the mechanical strength of traditional metallic armor. This breaks through the water depth application limitations of traditional metallic armored cables and provides a more reliable cable support solution for deep-sea operations. By setting a composite structure of metallic armor layer 32 and non-metallic armor layer 31 as the load-bearing layer, not only is the weight of the lightweight umbilical cable 100 reduced, but it also maintains high mechanical strength compared to non-metallic armored umbilical cables. This solves the problems of weak mechanical strength such as lateral pressure resistance of traditional metallic armored umbilical cables in ultra-deep water applications and traditional non-metallic armored umbilical cables.

[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A lightweight umbilical cable, characterized in that: The lightweight umbilical cable includes a main cable core, an inner sheath covering the main cable core, and an armor layer covering the inner sheath. The armor layer includes a non-metallic armor layer on the side closer to the inner sheath and a metallic armor layer on the side farther from the inner sheath.

2. The lightweight umbilical cable according to claim 1, characterized in that: The non-metallic armor layer is formed by twisting together multiple non-metallic wires or non-metallic strips, and the metallic armor layer is formed by twisting together multiple metal wires or metal strips.

3. The lightweight umbilical cable according to claim 1, characterized in that: The non-metallic wires or non-metallic strips are made of fiber-reinforced composite materials and covered with nylon material. The metallic wires or metallic strips are made of galvanized aluminum alloy steel wire and coated with anti-corrosion grease.

4. The lightweight umbilical cable according to claim 1, characterized in that: The metal armor layer and the non-metal armor are twisted in opposite directions.

5. The lightweight umbilical cable according to claim 1, characterized in that: The armor layer further includes at least one composite armor layer disposed between the non-metallic armor layer and the metallic armor layer, the composite armor layer being formed by alternating twisting of metal wires and non-metallic wires.

6. The lightweight umbilical cable according to claim 5, characterized in that: The composite armor layer consists of one layer, and the composite armor layer is twisted in the same direction as the non-metallic armor layer, but in the opposite direction to the metallic armor layer.

7. The lightweight umbilical cable according to claim 1, characterized in that: The main cable core includes a power unit, a control unit, and an optical fiber unit.

8. The lightweight umbilical cable according to claim 7, characterized in that: The control unit and the optical fiber unit are twisted together, and the control unit and the optical fiber unit are covered by an inner shielding layer to form an inner cable core, which is located in the middle of the total cable core.

9. The lightweight umbilical cable according to claim 8, characterized in that: The number of power units is multiple, and the total cable core also includes multiple ground wire units, and the multiple power units and ground wire units are uniformly twisted around the inner shielding layer.

10. The lightweight umbilical cable according to claim 7, characterized in that: The main cable core also includes an outer shielding layer, in which the power unit, control unit and optical fiber unit are housed, and the outer shielding layer is filled with water-blocking adhesive.

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