Mineral insulated cable

Abstract

The invention relates to the technical field of mineral insulated cables, and discloses a mineral insulated cable which comprises a high-temperature alarm mechanism and a joint reinforcing mechanism, the high-temperature alarm mechanism is arranged on the outer wall of a halogen-smoke-free polyolefin outer sheath, and by means of the characteristics that memory metal is large in bending amount, high in plasticity and capable of recovering the original shape at the temperature above the memory temperature, the high-temperature alarm mechanism can be used for alarming the halogen-smoke-free polyolefin outer sheath. Nickel-titanium alloy matched with the cable is made into a spiral shape to be wound on the outer wall of the cable, when the temperature reaches 600 DEG C or above, the shape of the memory metal recovers to drive the sliding base to move, the toothed plate arranged on the upper surface of the sliding base drives the iron block to ascend, the iron block can emit red light at the temperature of 600 DEG C, and the red light is emitted. And the crystal lampshade covering the iron block refracts the emitted red light to improve the brightness so as to remind an operator that the temperature is too high, and the memory metal can automatically recover to a normal shape when the temperature is recovered to below 600 DEG C.

Description

Technical Field

[0001] This invention relates to the field of mineral-insulated cable technology, specifically to a mineral-insulated cable. Background Technology

[0002] Mineral-insulated cables are cables in which a copper sheath encases a copper conductor core, and magnesium oxide powder is used as the inorganic insulation material to separate the conductor from the sheath. The outermost protective sheath can be selected as needed. Mineral-insulated cables are widely used in high-rise buildings, petrochemical plants, airports, tunnels, ships, offshore oil platforms, aerospace, steel metallurgy, shopping malls, parking lots, and other applications. Chinese patent CN202010440352.4 discloses a mineral-insulated cable, which includes, from the inside out, a cable core, an inner shielding layer, a mica tape layer, an inner insulation layer, an outer shielding layer, a quartz mesh layer, an outer insulation layer, and a sheath layer. The inner shielding layer uses modified expanded graphite fiber, and the outer shielding layer uses a composite of modified expanded graphite fiber / conductive carbon black. The inner insulation layer uses one or two of ceramicized silicone rubber and ceramicized polyolefin, and the outer insulation layer uses one or two of ceramicized silicone rubber and mica tape. By rationally designing the interlayer structure of the cable and optimizing the material composition, the insulation, flame retardancy, toughness, and wear resistance of the cable are greatly improved, and the comprehensive mechanical properties and electrical safety performance are significantly enhanced.

[0003] As can be seen from the above-mentioned apparatus, although the above-mentioned preparation method provides a mineral-insulated cable with excellent insulation, flame retardancy, toughness and abrasion resistance, the applicant believes that the following defects still exist: Existing mineral-insulated cables can only operate normally within a range of approximately 250°C when subjected to prolonged high temperatures in specific applications. They cannot function in environments with sustained high temperatures above 250°C. Furthermore, temperature measuring instruments and alarms are impractical in such environments, and the cables lack their own temperature alarm devices to alert operators when the temperature reaches the limit, leading to a reduction in cable lifespan. Summary of the Invention

[0004] (I) Technical problem to be solved: In view of the shortcomings of the prior art, the present invention provides a mineral insulated cable, which has the advantages of being resistant to high temperature and able to work in high temperature environment for a long time, and the cable has a built-in alarm with a set safe operating temperature. When the set temperature is exceeded, an alarm will be automatically issued. This solves the problem that the existing mineral insulated cables cannot work normally in a continuous high temperature environment for a long time, and there is no alarm device to limit the safe temperature alarm value of the cable, which causes safety hazards and affects the service life.

[0005] (II) Technical Solution: To achieve the above objectives, the present invention provides the following technical solution: a mineral-insulated cable, comprising a halogen-free smoke-free polyolefin outer sheath, a mineral oxygen barrier layer, a copper core stranded conductor, a mineral insulation layer, an inorganic mineral filling layer, and a high-temperature alarm mechanism. The high-temperature alarm mechanism is disposed on the outer wall of the halogen-free smoke-free polyolefin outer sheath. The high-temperature alarm mechanism includes a fixed base, an alarm base, a shape memory metal, a sliding base, a toothed plate, a gear, a rotating shaft, an iron block, and a crystal lampshade. A fixed base is fixedly installed on the left outer wall of the halogen-free smoke-free polyolefin outer sheath. The upper surface of the fixed base... An alarm base is fixedly installed on the surface. A shape memory metal is fixedly connected to the outer right side of the fixed base. A sliding base is fixedly connected to the other end of the shape memory metal. The sliding base is movably installed on the right side of the outer wall of the halogen-free smoke polyolefin outer sheath. A toothed plate is fixedly installed on the upper surface of the sliding base. Grooves are provided on both sides of the inner surface of the alarm base. A rotating shaft is movably connected to the inner surface of the two grooves. Two gears are fixedly installed on the outer walls of the rotating shafts on both sides inside the two grooves. An iron block is fixedly installed in the middle of the outer wall of the rotating shafts. A crystal lampshade is fixedly installed on the upper surface of the alarm base.

[0006] Preferably, the inner wall of the halogen-free polyolefin outer sheath is provided with a mineral oxygen barrier layer, the mineral oxygen barrier layer is filled with an inorganic mineral filling layer, the inorganic mineral filling layer is provided with four copper core stranded conductors, and the outer wall of the copper core stranded conductors is fitted with a mineral insulation layer.

[0007] Preferably, the shape memory metal is made of nickel-titanium alloy and is spring-wound to the outer wall of the halogen-free smokeless polyolefin outer sheath, with a deformation range of over 600 degrees Celsius.

[0008] Preferably, the connection reinforcement mechanism includes a movable top rod, an active cobalt magnet, a passive cobalt magnet, a slide rod, a slide groove, a reinforcement sleeve, a memory spring, and a reinforcement plate. The movable top rod is fixedly installed below the sliding base, and an active cobalt magnet is fixedly installed on the outer surface of the right end of the movable top rod.

[0009] Preferably, a reinforcing sleeve is provided on the inner surface of the fixed base, and a sliding rod is fixedly installed on the lower part of the outer wall of the reinforcing sleeve. The sliding rod is movably disposed in a sliding groove provided on the lower part of the outer wall of the fixed base, and a passive cobalt magnet is fixedly installed below the sliding rod.

[0010] Preferably, the inner wall of the reinforcing sleeve is provided with several annular grooves, and a memory spring is provided in the groove of the inner wall of the reinforcing sleeve. A reinforcing plate is fixedly installed at the other end of the memory spring.

[0011] Preferably, the Curie temperature of the active cobalt magnet and the passive cobalt magnet (33) is about 1121°C, which will not affect the magnetism of the cobalt magnet at 600°C.

[0012] (III) Beneficial Effects: Compared with the prior art, the present invention provides a mineral-insulated cable with the following beneficial effects: 1. This mineral-insulated cable features a copper core stranded conductor composed of multiple strands of copper monofilaments, exhibiting excellent flexibility. The inorganic mineral filling layer and mineral insulation layer utilize an extrusion structure, filled and coated with alumina, magnesium oxide, aluminum hydroxide, and calcium silicate in a specific ratio, resulting in a compact structure with excellent insulation and fire resistance. Simultaneously, a mineral oxygen barrier layer, composed of alumina, magnesium oxide, aluminum hydroxide, and calcium silicate, surrounds the inorganic mineral filling layer, providing good flame retardancy and fire resistance. Finally, the halogen-free smoke polyolefin outer sheath employs an extrusion structure, extruding halogen-free, low-smoke flame-retardant polyolefin as the outer sheath, composed of polyethylene, polypropylene, aluminum hydroxide, polyphosphate, and antioxidants in a specific ratio, exhibiting halogen-free, low-smoke, and flame-retardant properties. This cable can operate normally in continuously high-temperature environments and possesses superior fire resistance, along with characteristics such as flexibility, good bending performance, and low-smoke, halogen-free, and flame-retardant properties.

[0013] 2. This mineral-insulated cable incorporates a high-temperature alarm mechanism on its outer wall. Due to the high bending capacity and plasticity of shape memory metal, its internal crystal structure changes when the temperature reaches a certain value, resulting in a change in shape. It can recover its previous shape above the memory temperature. A nickel-titanium alloy, matching the cable, is spirally wound around the cable's outer wall. When the temperature reaches above 600℃, the shape memory metal recovers, causing the sliding base to move. A toothed plate on the upper surface of the sliding base raises an iron block. At 600℃, the iron block emits red light, which is refracted by a crystal lampshade covering the block to increase brightness, alerting the operator to excessive temperature. When the temperature returns to below 600℃, the shape memory metal automatically returns to its normal shape.

[0014] 3. This mineral-insulated cable, through the cooperation between the high-temperature alarm mechanism 2 and the connection reinforcement mechanism 3, achieves the following: when the memory metal in the high-temperature alarm mechanism deforms at 600℃, it simultaneously drives the moving push rod to move. The active cobalt magnet of the moving push rod and the passive cobalt magnet of the slide rod 34 attract each other, while also correcting the position of the toothed plate to ensure meshing with the gear. During the movement, the moving push rod drives the slide rod to move within the limited surface of the slide groove. The slide rod drives the reinforcement sleeve to extend out to reinforce the connection between the two cables. At the same time, the memory spring set in the reinforcement sleeve begins to deform after the reinforcement sleeve moves out of the fixed base, driving the reinforcement plate to push upward to fix and support the cable, effectively preventing sudden power failure and safety accidents caused by cable breakage during use. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2This is a schematic diagram of the cable disassembly structure of the present invention; Figure 3 This is a schematic diagram of the reinforcement mechanism at the connection point after deformation of the shape memory metal according to the present invention; Figure 4 This is a schematic diagram of the high-temperature alarm mechanism for memory metal deformation according to the present invention.

[0016] The numbers on the map are: 1. Halogen-free smokeless polyolefin outer sheath; 11. Mineral oxygen barrier layer; 12. Copper core stranded conductor; 13. Mineral insulation layer; 14. Inorganic mineral filling layer; 2. High-temperature alarm mechanism; 21. Fixed base; 22. Alarm base; 23. Shape memory metal; 24. Sliding base; 25. Gear plate; 26. Gear; 27. Rotating shaft; 28. Iron block; 29. ​​Crystal lampshade; 3. Connection reinforcement mechanism; 31. Moving top rod; 32. Active cobalt magnet; 33. Passive cobalt magnet; 34. Slide rod; 35. Slide groove; 36. Reinforcing sleeve; 37. Memory spring; 38. Reinforcing plate. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0018] Embodiment 1 of the present invention: Please refer to Figure 1 , Figure 4A mineral-insulated cable includes a halogen-free smoke polyolefin outer sheath 1, a mineral oxygen barrier layer 11, a copper core stranded conductor 12, a mineral insulation layer 13, an inorganic mineral filling layer 14, and a high-temperature alarm mechanism 2. The high-temperature alarm mechanism 2 is disposed on the outer wall of the halogen-free smoke polyolefin outer sheath 1. The high-temperature alarm mechanism 2 includes a fixed base 21, an alarm base 22, a shape memory metal 23, a sliding base 24, a toothed plate 25, a gear 26, a rotating shaft 27, an iron block 28, and a crystal lampshade 29. The fixed base 21 is fixedly installed on the left outer wall of the halogen-free smoke polyolefin outer sheath 1. The alarm base 22 is fixedly installed on the upper surface of the fixed base 21. The shape memory metal 23 is fixedly connected to the right outer surface of the fixed base 21. Metal 23, the shape memory metal 23 is made of nickel-titanium alloy and is wound around the outer wall of the halogen-free smoke polyolefin outer sheath 1 with a spring. Its deformation range is above 600 degrees Celsius. The other end of the shape memory metal 23 is fixedly connected to a sliding base 24. The sliding base 24 is movably installed on the right side of the outer wall of the halogen-free smoke polyolefin outer sheath 1. A toothed plate 25 is fixedly installed on the upper surface of the sliding base 24. The inner surface of the alarm base 22 has grooves on both sides. The inner surface of the grooves on both sides is movably connected to a rotating shaft 27. Two gears 26 are fixedly installed on the outer walls of the rotating shaft 27 on both sides inside the grooves. An iron block 28 is fixedly installed in the middle of the outer wall of the rotating shaft 27. A crystal lampshade 29 is fixedly installed on the upper surface of the alarm base 22.

[0019] Embodiment 2 of the present invention: Please refer to Figure 1-2 The connection reinforcement mechanism 3 includes a movable top rod 31, an active cobalt magnet 32, a passive cobalt magnet 33, a slide rod 34, a slide groove 35, a reinforcement sleeve 36, a memory spring 37, and a reinforcement plate 38. The movable top rod 31 is fixedly installed below the sliding base 24. An active cobalt magnet 32 ​​is fixedly installed on the outer surface of the right end of the movable top rod 31. A reinforcement sleeve 36 is provided on the inner surface of the fixed base 21. A slide rod 34 is fixedly installed on the lower part of the outer wall of the reinforcement sleeve 36. The slide rod 34 is movably disposed in the slide groove 35 provided on the lower part of the outer wall of the fixed base 21. A passive cobalt magnet 33 is fixedly installed below the slide rod 34. The inner wall of the reinforcement sleeve 36 is provided with several annular grooves. A memory spring 37 is provided in the grooves on the inner wall of the reinforcement sleeve 36. A reinforcement plate 38 is fixedly installed on the other end of the memory spring. The Curie temperature of the active cobalt magnet 32 ​​and the passive cobalt magnet 33 is about 1121°C, and the magnetism of the cobalt magnet will not be affected at 600°C.

[0020] Embodiment 3 of the present invention: Please refer to Figure 1 , Figure 3The halogen-free smoke polyolefin outer sheath 1 is composed of polyethylene, polypropylene, aluminum hydroxide, polyphosphate, and antioxidants, wherein polyethylene accounts for 50%, polypropylene for 20%, aluminum hydroxide for 10%, polyphosphate for 5%, and antioxidants for 5%. The inner wall of the halogen-free smoke polyolefin outer sheath 1 is provided with a mineral oxygen barrier layer 11, which is composed of aluminum oxide, magnesium oxide, aluminum hydroxide, and calcium silicate, wherein aluminum oxide accounts for 40%, magnesium oxide for 30%, and aluminum hydroxide for 2%. 10. The calcium silicate content is 10%. The mineral oxygen barrier layer 11 is filled with an inorganic mineral filling layer 14. The inorganic mineral filling layer 14 is composed of alumina, magnesium oxide, aluminum hydroxide and calcium silicate, of which alumina and magnesium oxide each account for 30%, and aluminum hydroxide and calcium silicate each account for 20%. The inorganic mineral filling layer 14 is provided with four copper core stranded conductors 12. The outer wall of the copper core stranded conductors 12 is fitted with a mineral insulation layer 13. The mineral insulation layer 13 is composed of quartz and alumina, with a filling ratio of 70% quartz and 30% alumina.

[0021] The complete usage steps and working principles of the above embodiments one and two are as follows: Firstly, mineral-insulated cables are designed for use in high-temperature environments such as oil refineries and steel mills. They can operate normally up to 600℃ and have been tested to function normally for 180 minutes at 950℃. Temperatures exceeding 600℃ will reduce the cable's lifespan. The manufacturing process of mineral-insulated cables is as follows: The copper core stranded conductor 12 adopts a stranded structure, in which multiple copper single wires are stranded in a regular arrangement. The outermost layer is stranded in the left direction. The stranding is carried out in layers, with adjacent layers stranded in opposite directions, which ensures the tightness and structural stability of the copper core stranded conductor 12. After stranding, the conductor surface is smooth, free of oil stains, burrs or sharp edges that damage the insulation, and no protruding or broken single wires.

[0022] The mineral insulation layer 13 adopts a wrapping structure, with two layers overlapping and wrapping around the copper core stranded conductor 12. The mineral insulation layer 13 is composed of quartz and alumina, with a filling ratio of 70% quartz and 30% alumina.

[0023] The inorganic mineral filler layer 14 adopts an extrusion structure, filling the gaps between the wire cores and the inner surface of the mineral oxygen barrier layer 11 with alumina, magnesium oxide, aluminum hydroxide, and calcium silicate, forming an integrated structure of filling and outer insulation. Alumina and magnesium oxide each account for 30%, while aluminum hydroxide and calcium silicate each account for 20%. The average coating thickness should not be less than the nominal value, and the thinnest point thickness should not be less than 90% of the nominal thickness. The eccentricity should not exceed 15%. The extruded surface should be smooth, free from sharp corners, particles, scorching, scratches, etc.

[0024] The mineral oxygen barrier layer 11, which is wrapped around the outer surface of the inorganic mineral filling layer 14, is composed of aluminum oxide, magnesium oxide, aluminum hydroxide and calcium silicate, wherein aluminum oxide accounts for 40%, magnesium oxide accounts for 30%, aluminum hydroxide accounts for 20%, and calcium silicate accounts for 10%.

[0025] The halogen-free smoke polyolefin outer sheath 1 adopts an extrusion structure, extruding halogen-free low-smoke flame-retardant polyolefin as the outer sheath, composed of polyethylene, polypropylene, aluminum hydroxide, polyphosphate, and antioxidants. Polyethylene accounts for 50%, polypropylene 20%, aluminum hydroxide 10%, polyphosphate 5%, and antioxidants 5%. The average extrusion thickness should not be less than the nominal value, and the thinnest point thickness should not be less than 85% of the nominal thickness. The extruded surface should be smooth, free from sharp corners, particles, scorching, scratches, etc. This method of manufacturing enhances the heat resistance and mechanical properties of mineral-insulated cables, making them more durable and providing better protection against high temperatures.

[0026] Secondly, a high-temperature alarm mechanism 2 is installed on the outer wall of the halogen-free polyolefin outer sheath 1 of the cable. A fixed base 21 and a sliding base 24 are fixedly connected by a shape memory metal 23. The shape memory metal 23 is made of nickel-titanium alloy. When the temperature rises above 600℃, the shape memory metal 23 deforms, pulling the sliding base 24 towards the fixed base 21. When the sliding base 24 moves to the fixed base 21, the toothed plate 25 fixedly installed on top of the sliding base 24 moves into the grooves on both sides of the alarm base 22. The teeth on the surface of the toothed plate 25 drive the gear 26 to rotate, which in turn drives the iron block 28 to rotate and move it to a vertical position. The iron block 28 turns red at 600℃. A crystal lampshade 29 fixedly installed on the upper surface of the alarm base 22 covers the iron block, and the crystal lampshade 29 refracts the red light emitted by the iron block 28. The light amplifies, thus reminding employees that the temperature has reached the warning value and that the working environment needs to be cooled to prevent cable damage and accidents. Simultaneously, the shape memory metal 23 deforms, causing the movable push rod 31 to move. When the movable push rod 31 moves to the vicinity of the slide rod 34, the active cobalt magnet 32 ​​and the passive cobalt magnet 33 attract each other, causing the slide rod 34 to continue its limited movement within the slide groove 35. As the slide rod 34 moves, it also moves the reinforcing sleeve 36. When the slide rod 34 reaches the edge of the slide groove 35, the reinforcing sleeve 36 reinforces and wraps the connection between the two cables. Furthermore, the shape memory spring 37 inside the reinforcing sleeve 36 begins to deform when it moves out of the fixed base 21, lifting the reinforcing sleeve 36 to provide fixed support for the other cable, preventing the cable connection from breaking due to excessive temperature and avoiding sudden power outages that could disrupt work.

[0027] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mineral-insulated cable, comprising a halogen-free polyolefin outer sheath (1), a mineral oxygen barrier layer (11), a copper core stranded conductor (12), a mineral insulation layer (13), an inorganic mineral filling layer (14), a high-temperature alarm mechanism (2), and a connection reinforcement mechanism (3), characterized in that: The high temperature alarm mechanism (2) is installed on the outer wall of the halogen-free polyolefin outer sheath (1); The high temperature alarm mechanism (2) includes a fixed base (21), an alarm base (22), a shape memory metal (23), a sliding base (24), a toothed plate (25), a gear (26), a rotating shaft (27), an iron block (28), and a crystal lampshade (29). The fixed base (21) is fixedly installed on the left outer wall of the halogen-free polyolefin outer sheath (1), and the alarm base (22) is fixedly installed on the upper surface of the fixed base (21). The right outer surface of the fixed base (21) is fixedly connected to a shape memory metal (23), and the other end of the shape memory metal (23) is fixedly connected to a sliding base (24). The sliding base (24) is movably installed on the right side of the outer wall of the halogen-free smoke polyolefin outer sheath (1), and a toothed plate (25) is fixedly installed on the upper surface of the sliding base (24). The alarm base (22) has grooves on both sides of its inner surface. A rotating shaft (27) is movably connected to the inner surface of the grooves on both sides. Two gears (26) are fixedly installed on the outer walls of the rotating shaft (27) on both sides inside the grooves. An iron block (28) is fixedly installed in the middle of the outer wall of the rotating shaft (27). A crystal lampshade (29) is fixedly installed on the upper surface of the alarm base (22).

2. The mineral-insulated cable according to claim 1, characterized in that: The inner wall of the halogen-free polyolefin outer sheath (1) is provided with a mineral oxygen barrier layer (11), the mineral oxygen barrier layer (11) is filled with an inorganic mineral filling layer (14), the inorganic mineral filling layer (14) is provided with four copper core stranded conductors (12), and the outer wall of the copper core stranded conductors (12) is fitted with a mineral insulation layer (13).

3. A mineral-insulated cable according to claim 1, characterized in that: The shape memory metal (23) is made of nickel-titanium alloy and is wound around the outer wall of the halogen-free smokeless polyolefin outer sheath (1) in a spring-loaded manner. Its deformation range is above 600 degrees Celsius.

4. A mineral-insulated cable according to claim 1, characterized in that: The connection reinforcement mechanism (3) includes a movable top rod (31), an active cobalt magnet (32), a passive cobalt magnet (33), a slide rod (34), a slide groove (35), a reinforcement sleeve (36), a memory spring (37), and a reinforcement plate (38). The movable top rod (31) is fixedly installed below the sliding base (24), and an active cobalt magnet (32) is fixedly installed on the outer surface of the right end of the movable top rod (31).

5. A mineral-insulated cable according to claim 4, characterized in that: A reinforcing sleeve (36) is provided on the inner surface of the fixed base (21). A sliding rod (34) is fixedly installed on the lower part of the outer wall of the reinforcing sleeve (36). The sliding rod (34) is movably disposed in the sliding groove (35) provided on the lower part of the outer wall of the fixed base (21). A passive cobalt magnet (33) is fixedly installed below the sliding rod (34).

6. A mineral-insulated cable according to claim 5, characterized in that: The inner wall of the reinforcing sleeve (36) is provided with several annular grooves, and a memory spring (37) is provided in the groove of the inner wall of the reinforcing sleeve (36). A reinforcing plate (38) is fixedly installed at the other end of the memory spring.

7. A mineral-insulated cable according to claim 1, characterized in that: The Curie temperature of the active cobalt magnet (32) and the passive cobalt magnet (33) is about 1121°C, and the magnetism of the cobalt magnet will not be affected at 600°C.

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