Cross-linked polyethylene insulated flame-retardant control cable

Abstract

The invention discloses a cross-linked polyethylene insulated flame-retardant control cable applied to the field of cables, according to the scheme, a physical protection structure for cooling and fire prevention is externally arranged, when the local temperature of the cable is too high, a temperature-sensing wrapper can imitate bark to expand outwards layer by layer, on one hand, part of heat directly carried by the outside is separated from the cable, and on the other hand, the temperature-sensing wrapper can directly carry heat; on the other hand, when the temperature-sensitive wrapping is unfolded outwards, the surface of the temperature-sensitive wrapping at the inner layer presents fluorescence, so that the abnormity of the cable can be effectively indicated for a worker, the abnormity of the cable can be timely found when the cable is smoldered or does not appear open fire, and the safety of the cable is improved. A worker can carry out corresponding treatment in time, and the fire occurrence rate is reduced; through the arrangement of the limiting unit, after continuous abnormal temperature rise, the unfolded temperature sensing sheath can be pushed to be directly and thoroughly separated from the cable, and the state change can play a further early warning effect on a worker and can indicate the emergency degree of high temperature of the cable.

Description

Technical Field

[0001] This invention relates to the field of cables, and in particular to a cross-linked polyethylene insulated flame-retardant control cable. Background Technology

[0002] Control cables are PVC insulated and PVC sheathed control cables suitable for use in industrial and mining enterprises, energy and transportation departments, and for control and protection circuits with AC rated voltage below 450 / 750 volts. Low-smoke halogen-free flame-retardant cables are difficult to ignite and have the ability to prevent or prevent the spread of fire. They are generally composed of conductors, insulation layers, sheath layers, and possibly shielding layers. The conductors are usually made of metal materials such as copper or aluminum to ensure good conductivity. The insulation and sheath layers are the key parts to achieve low-smoke flame-retardant performance. They are made of special flame-retardant materials. The flame-retardant principle is mainly to add flame retardants and other substances to the insulation and sheath materials of the cable. When the cable encounters a flame, the flame retardant will undergo a series of chemical reactions, such as endothermic decomposition, covering and isolating, and inhibiting free radicals, thereby preventing the spread of the flame and giving the cable flame-retardant properties. The low-smoke characteristic is achieved by selecting appropriate materials and formulas to reduce the generation and release of smoke during combustion. For example, Chinese patent CN117594294B discloses a fire-resistant and flame-retardant special cable and its production process.

[0003] When cables are in use, unexpected situations such as overload or short circuits can easily lead to abnormal local temperature increases. However, existing cables lack early warning and protection structures. For example, the flame-retardant cable disclosed in Chinese patent CN105161201B cannot take timely measures when the temperature rises abnormally, which can easily lead to smoldering and, in severe cases, even open flames that cause fires, posing a significant safety hazard. Furthermore, when the cable encounters a flame, the excessively high temperature can easily damage the cable, causing the control system to malfunction. This prevents instructions for guiding personnel evacuation and emergency fire suppression from being executed as expected. At the same time, the malfunction of the control system can also cut off communication with the outside world, making it difficult for external rescue personnel to carry out targeted rescue operations. Summary of the Invention

[0004] The core of this invention lies in the external physical protection structure used for cooling and fire prevention. When a local abnormal temperature rise occurs, it can peel off layer by layer like tree bark. On the one hand, it can effectively carry some heat away from the cable, thereby accelerating the cooling of the abnormal point. On the other hand, its obvious morphological change can effectively alert the staff to the cable abnormality, making it easier to carry out relevant maintenance measures in a timely manner and effectively avoid causing a fire, thus solving the safety hazards caused by abnormal cable temperature rise in the existing technology.

[0005] To solve the above problems, the present invention adopts the following technical solution.

[0006] A cross-linked polyethylene insulated flame-retardant control cable includes a cable body and a protective layer disposed outside the cable body. The cable body includes multiple cable cores, an insulation layer wrapped around the multiple cable cores, and an inner protective layer located outside the insulation layer. The protective layer includes a heat insulation layer fixedly wrapped around the inner protective layer, multiple axial isolation strips respectively fixedly connected to the outer end of the heat insulation layer, and multiple rows of outer protective layers respectively located between two adjacent axial isolation strips. The multiple axial isolation strips are arranged in a ring array. There are multiple outer protective layers in each row. Multiple radial isolation rings are also distributed at intervals in the multiple outer protective layers in the same row. The multiple radial isolation rings are all fixedly connected to the outer wall of the heat insulation layer.

[0007] Furthermore, the outer protective layer includes multiple temperature-sensitive sheaths stacked on top of each other. Each temperature-sensitive sheath has multiple embedded wires fixedly embedded in its center. The multiple embedded wires are distributed along the circumference of the cable body. One end of each embedded wire is fixedly wrapped with a fluorescent layer. The multiple embedded wires are made of double-pass memory alloy material, and the embedded wires exhibit a shrinkage state when the temperature is above the critical temperature.

[0008] Furthermore, apart from the outermost temperature-sensitive foreskin, the outer surfaces of the remaining temperature-sensitive foreskins are coated with fluorescent layers, and each fluorescent layer has a different color.

[0009] Optionally, the axial isolation strip includes a semi-connected layer and a fastening layer fixedly connected to the semi-connected layer. The two ends of the embedded wire pass through the fastening layer and the semi-connected layer of the two axial isolation strips respectively. The fastening layer is made of a hard, high-melting-point material with a melting point of 90-100℃. The semi-connected layer is made of a low-melting-point material with a melting point of 60-70℃. Multiple fluorescent layers are fixedly embedded in the fastening layer.

[0010] Optionally, multiple fluorescent layers are distributed in an alternating manner, and the other end of the embedded wire is fixedly wrapped with a pre-melted layer, which is made of a low-melting-point material and has a melting point temperature of 60-70℃.

[0011] Optionally, blind holes are drilled on the axial isolation strip, and the fluorescent layer corresponds to the blind holes. An annular groove is also drilled on the inner wall of the blind hole. A limiting unit is provided in the blind hole. The limiting unit includes a pre-push layer located at the bottom of the blind hole and a T-shaped adhesive layer wrapped around the fluorescent layer. The T-shaped adhesive layer extends into the annular groove.

[0012] Furthermore, the pre-push layer is made of a high-temperature resistant elastic material, and the pre-push layer is in a compressed state. The length of the pre-push layer when it is not under compressive force is greater than the depth of the blind hole.

[0013] Furthermore, the T-shaped adhesive layer is also made of hot-melt material, and the melting point of the T-shaped adhesive layer is higher than that of the pre-melted layer.

[0014] Compared with the prior art, the advantages of this invention are:

[0015] This solution incorporates an external physical protection structure for cooling and fire prevention. When the cable experiences localized overheating, the heat-sensing sheath unfolds outward layer by layer, mimicking tree bark. On one hand, this separates some of the heat carried by the outer layer from the cable, protecting it from damage and extending the time before it ignites due to abnormally high temperatures. On the other hand, as the heat-sensing sheath unfolds, the inner layer fluoresces, effectively indicating the cable's abnormality to staff. This allows for timely detection of abnormalities, even in cases of smoldering or before open flames, enabling staff to take appropriate action and reduce the fire rate.

[0016] (2) At the same time, if the staff fails to deal with the abnormal temperature rise in time, the biomimetic layer-by-layer peeling structure will also slow down the rate of cable temperature rise, so as to extend the effective working life of the cable during the fire, thereby extending the effective working time of the automatic control system at the fire point, and gaining more time for the early self-rescue and later rescue at the fire point, so as to solve the safety hazards caused by the abnormal temperature rise of the cable in the existing technology.

[0017] (3) By setting the limit unit, when the cable temperature is too high, the limit unit is triggered, which can push the unfolded temperature sensing sheath to separate directly from the cable, so that it is further away from the cable. This change in state can provide a further warning to the staff and indicate the urgency of the cable temperature. Attached Figure Description

[0018] Figure 1 This is a perspective view of the present invention;

[0019] Figure 2 This is a radial cross-sectional view of the present invention;

[0020] Figure 3 This is a partial cross-sectional schematic diagram of the outer protective layer of the present invention;

[0021] Figure 4 This is a schematic diagram of the connection between two adjacent outer protective layers of the present invention;

[0022] Figure 5 This is a schematic diagram of the temperature-sensitive foreskin of the present invention unfolding outwards;

[0023] Figure 6 This is a schematic diagram of the temperature-sensitive foreskin unfolding outwards from another angle, according to the present invention.

[0024] Figure 7 This is a radial cross-sectional view of the cable when the temperature-sensing sheath of the present invention bursts open outward;

[0025] Figure 8 This is a schematic diagram of the temperature-sensing foreskin layered and stacked according to the present invention;

[0026] Figure 9This is a schematic diagram of the temperature-sensitive foreskin of the present invention being pushed open outward by the staggered and stacked layers;

[0027] Figure 10 This is a schematic diagram of the temperature-sensing foreskin end portion when a limiting unit is added according to the present invention;

[0028] Figure 11 This is a schematic diagram of the present invention, which directly pushes away the temperature-sensing foreskin when there is an abnormally high temperature after the addition of a limiting unit.

[0029] Explanation of the labels in the diagram:

[0030] 11 Cable core, 12 Insulation layer, 13 Inner protective layer, 2 Heat insulation layer, 3 Outer protective layer, 31 Temperature sensing sheath, 32 Embedded wire, 33 Fluorescent layer, 301 Reinforcing block, 302 Pre-melted layer, 4 Axial isolation strip, 41 Semi-connected layer, 42 Fastening layer, 401 Blind hole, 402 Annular groove, 51 Pre-push layer, 52 T-shaped adhesive layer, 6 Radial isolation ring. Detailed Implementation

[0031] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0032] First implementation method:

[0033] Figures 1-2 The diagram shows a cross-linked polyethylene insulated flame-retardant control cable, comprising a cable body and a protective layer disposed outside the cable body. The cable body includes multiple cable cores 11, an insulation layer 12 wrapped around the multiple cable cores 11, and an inner protective layer 13 located outside the insulation layer 12. The protective layer includes a heat insulation layer 2 fixedly wrapped around the inner protective layer 13, multiple axial isolation strips 4 respectively fixedly connected to the outer ends of the heat insulation layer 2, and multiple rows of outer protective layers 3 respectively located between two adjacent axial isolation strips 4. The multiple axial isolation strips 4 are arranged in a ring array. Each row of outer protective layers 3 contains multiple outer protective layers 3. Multiple radial isolation rings 6 are also spaced apart in the multiple outer protective layers 3 in the same row. Each radial isolation ring 6 is fixedly connected to the outer wall of the insulation layer 2. The radial isolation ring 6 is made of a high heat insulation material. Through the setting of multiple axial isolation strips 4 and multiple radial isolation rings 6, the outer wall of 1 is modularized. When abnormal high temperature occurs, the outer protective layer 3 at the corresponding module can achieve biomimetic peeling, reducing the impact on the outer protective layer 3 of other areas. After an abnormality occurs, the staff only needs to replace the outer protective layer 3 at the abnormal point, or directly cut the cable at the abnormal point along the radial isolation ring 6, replace the cable at that point, and connect it using conventional technical means. In this way, when there is a local high temperature abnormality, the impact on the cable is not too large, effectively reducing the loss.

[0034] like Figure 3The outer protective layer 3 includes multiple temperature-sensitive sheaths 31 stacked on top of each other. Each temperature-sensitive sheath 31 has multiple embedded wires 32 fixedly embedded in its center. The multiple embedded wires 32 are distributed along the circumference of the cable body. One end of each embedded wire 32 is fixedly wrapped with a fluorescent layer 301. Due to the setting of the fluorescent layer 301, one side of the temperature-sensitive sheath 31 is relatively fixed, while the other side is relatively less stable. When abnormal high temperature occurs and the embedded wires 32 shrink, the other side of the temperature-sensitive sheath 31 can smoothly detach from the axial isolation strip 4, thus presenting an outward unfolding state, which can serve as a reminder to the staff. The multiple embedded wires 32 are all made of double-path memory alloy material, and the embedded wires 32 exhibit a shrinking state when the temperature is above the critical temperature. After abnormal high temperature, with one side of the fluorescent layer 301 as the fulcrum, the embedded wires 32 can shrink towards the fulcrum side, thereby causing the other end of the temperature-sensitive sheath 31 to break apart from the axial isolation strip 4, presenting a biomimetic tree bark peeling state.

[0035] It is worth noting that multiple fluorescent layers 301 on the same temperature-sensing sheath 31 are located on the same side, so that when there is an abnormal high temperature, the temperature-sensing sheath 31 will break open to one side as a whole, and it is not easy for both sides to contract simultaneously, resulting in the force being dispersed, making it difficult for the temperature-sensing sheath 31 to break open outward. This effectively ensures the indication effect of the outer protective layer 3 on cable abnormalities, and at the same time, it can carry some heat away from the cable, improving the safety and reliability of the cable.

[0036] Except for the outermost heat-sensitive sheath 31, the outer surfaces of the remaining heat-sensitive sheaths 31 are coated with fluorescent layers 33, and each fluorescent layer 33 has a different color. When one end of the heat-sensitive sheath 31 is broken open and peeled off, the inner fluorescent layer 33 can be exposed. For cables installed in corners where the light is relatively low, this can improve the warning level of abnormalities, making it easier for staff to detect cable abnormalities in time and eliminate potential hazards before open flames appear, thereby effectively reducing safety risks.

[0037] like Figure 4The axial isolation strip 4 includes a semi-connected layer 41 and a fastening layer 42 fixedly connected to the semi-connected layer 41. The two ends of the embedded wire 32 pass through the fastening layer 42 and the semi-connected layer 41 of the two axial isolation strips 4, respectively. The fastening layer 42 is made of a hard, high-melting-point material with a melting point of 90-100℃. The semi-connected layer 41 is made of a low-melting-point material with a melting point of 60-70℃. Multiple fluorescent layers 301 are fixedly embedded in the fastening layer 42. The critical temperature of the embedded wire 32 is consistent with the melting point temperature of the semi-connected layer 41. When the temperature reaches the melting point of the semi-connected layer 41, the semi-connected layer 41 gradually melts, thereby reducing the impact on… The binding force of the embedded wire 32 allows it to easily separate from the axial isolation strip 4 when it contracts. The fastening layer 42 has a higher melting point temperature so that it remains stable when the semi-connected layer 41 is fused, thus binding the fluorescent layer 301. This allows one end of the embedded wire 32 to act as a fulcrum and function stably, facilitating the peeling off of the other side of the temperature-sensing sheath 31. If the temperature rises to the melting point temperature of the fastening layer 42, the other side of the temperature-sensing sheath 31 will also peel off. After noticing the abnormality, the staff can quickly make a preliminary judgment on the heating status of the cable based on the peeling of the temperature-sensing sheath 31, which facilitates the rapid identification of the emergency and timely handling.

[0038] like Figures 5-7 This solution utilizes an external physical protection structure for cooling and fire prevention. When the cable experiences localized overheating, the heat-sensing sheath 31 unfolds outward layer by layer, mimicking tree bark. On one hand, this separates some of the heat carried by the outside from the cable, protecting it from damage and extending the time before the cable ignites due to abnormally high temperatures. On the other hand, as the heat-sensing sheath 31 unfolds outward, the inner layer of the sheath 31 glows, effectively indicating the cable's abnormality to staff. This allows for timely detection of abnormalities when the cable is smoldering or before an open flame appears, enabling staff to take appropriate action and reduce the fire rate.

[0039] Meanwhile, if staff fail to address the abnormal temperature rise in a timely manner, the biomimetic layered peeling structure will also slow down the rate of cable heating, thereby extending the effective working life of the cable during a fire and extending the effective working time of the automated control system at the fire point. This will buy more time for the initial self-rescue and subsequent rescue efforts at the fire point, thus solving the safety hazards caused by abnormal cable heating in existing technologies.

[0040] Second implementation method:

[0041] This embodiment is based on the first embodiment, but changes the orientation of the fluorescent layer 301 in the temperature-sensing foreskin 31, while the rest remains the same as the first embodiment.

[0042] like Figure 8In this embodiment, the axial isolation strip 4 is integrally formed, without separate semi-connecting layers 41 and fastening layers 42. The material of the axial isolation strip 4 as a whole is consistent with that of the fastening layer 42 in the first embodiment. Specifically, multiple fluorescent layers 301 are interleaved, and the other end of the embedded wire 32 is externally wrapped with a pre-melted layer 302. The pre-melted layer 302 is made of a low-melting-point material, and its melting point temperature is 60-70°C. Figure 9 When the cable experiences localized abnormal high temperatures, initially, the ends of multiple temperature-sensing sheaths 31 unfold outwards alternately. The inner temperature-sensing sheath 31 can push up the outer temperature-sensing sheath 31, increasing the unfolding range and thus moving the temperature-sensing sheath 31 as far away from the cable as possible. At the same time, more of the inner fluorescent layer 33 is exposed, making the light emission more obvious and providing a better warning effect for abnormalities.

[0043] The third implementation method:

[0044] This embodiment adds a limiting unit based on the first or second embodiment, while the rest remains the same as the first or second embodiment.

[0045] Figure 10 As shown, a blind hole 401 is drilled in the axial isolation strip 4, and the fluorescent layer 301 corresponds to the blind hole 401. An annular groove 402 is also drilled in the inner wall of the blind hole 401. A limiting unit is provided in the blind hole 401. The limiting unit includes a pre-push layer 51 located at the bottom of the blind hole 401 and a T-shaped adhesive layer 52 wrapped around the fluorescent layer 301. The T-shaped adhesive layer 52 extends into the annular groove 402. The pre-push layer 51 is made of a high-temperature resistant elastic material and is in a compressed state. The length of the pre-push layer 51 when not under compressive force is greater than the depth of the blind hole 401. Figure 11 When the cable experiences abnormally high temperatures and the temperature reaches the melting point of the T-shaped adhesive layer 52, the T-shaped adhesive layer 52 melts, thereby releasing the restriction on the pre-push layer 51 and the fluorescent layer 301. Under its restoring elasticity, the temperature-sensing sheath 31 can be pushed outward, thus completely peeling the temperature-sensing sheath 31 off from the cable. On the one hand, this allows the staff to make a preliminary judgment on the approximate abnormal high temperature based on the state of the temperature-sensing sheath 31. On the other hand, it keeps the temperature-sensing sheath 31 as far away from the cable body as possible, thereby removing it from external high-temperature points or ignition points, thus alleviating the high temperature of the cable.

[0046] The T-shaped adhesive layer 52 is also made of hot melt material, and the melting point of the T-shaped adhesive layer 52 is higher than that of the pre-melted layer 302. This effectively ensures that the end of the temperature-sensing sheath 31 and the axial isolation strip 4 breaks off and separates first, and then directly separates from the outer protective layer 3. This effectively ensures that the temperature-sensing sheath 31 is stably peeled off from the cable.

[0047] By setting the limiting unit, when the cable temperature is too high, the limiting unit is triggered, which in turn pushes the unfolded temperature-sensing sheath 31 to separate directly from the cable, making it further away from the cable. The complete separation of the temperature-sensing sheath 31 can provide further early warning to the staff and indicate the urgency of the cable's high temperature.

[0048] The above are merely preferred embodiments of the present invention; they encompass all the protection scope of the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solutions and improved concepts of the present invention, should be covered within the protection scope of the present invention.

Claims

1. A cross-linked polyethylene insulated flame-retardant control cable, comprising a cable body and a protective layer disposed outside the cable body, characterized in that: The cable body includes multiple cable cores (11), an insulation layer (12) wrapped around the multiple cable cores (11), and an inner protective layer (13) located outside the insulation layer (12). The protective layer includes a heat insulation layer (2) fixedly wrapped around the inner protective layer (13), multiple axial isolation strips (4) respectively fixedly connected to the outer end of the heat insulation layer (2), and multiple rows of outer protective layers (3) respectively located between two adjacent axial isolation strips (4). The multiple axial isolation strips (4) are arranged in a ring array. The number of outer protective layers (3) in each row is multiple. Multiple radial isolation rings (6) are also distributed at intervals in the multiple outer protective layers (3) in the same row. The multiple radial isolation rings (6) are all fixedly connected to the outer wall of the heat insulation layer (2).

2. The cross-linked polyethylene insulated flame-retardant control cable according to claim 1, characterized in that: The outer protective layer (3) includes multiple temperature-sensitive sheaths (31) stacked on top of each other. Each temperature-sensitive sheath (31) has multiple embedded wires (32) fixedly embedded at its center. The multiple embedded wires (32) are distributed along the circumference of the cable body. One end of each embedded wire (32) is fixedly wrapped with a fluorescent layer (301). The multiple embedded wires (32) are made of double-pass memory alloy material, and the embedded wires (32) exhibit a shrinkage state when the temperature is above the critical temperature.

3. The cross-linked polyethylene insulated flame-retardant control cable according to claim 2, characterized in that: Except for the outermost temperature-sensitive foreskin (31), the outer surfaces of the remaining multiple temperature-sensitive foreskins (31) are coated with fluorescent layers (33), and each fluorescent layer (33) has a different color.

4. The cross-linked polyethylene insulated flame-retardant control cable according to claim 3, characterized in that: The axial isolation strip (4) includes a semi-connected layer (41) and a fastening layer (42) fixedly connected to the semi-connected layer (41). The two ends of the embedded wire (32) pass through the fastening layer (42) and the semi-connected layer (41) of the two axial isolation strips (4) respectively. The fastening layer (42) is made of a hard, high-melting-point material and the melting point temperature of the fastening layer (42) is 90-100°C. The semi-connected layer (41) is made of a low-melting-point material and the melting point temperature of the semi-connected layer (41) is 60-70°C. Multiple fluorescent layers (301) are fixedly embedded in the fastening layer (42).

5. A cross-linked polyethylene insulated flame-retardant control cable according to claim 4, characterized in that: Multiple fluorescent layers (301) are interleaved, and the other end of the embedded wire (32) is fixedly wrapped with a pre-melted layer (302). The pre-melted layer (302) is made of a low-melting-point material and the melting point temperature of the pre-melted layer (302) is 60-70℃.

6. The cross-linked polyethylene insulated flame-retardant control cable according to claim 4, characterized in that: A blind hole (401) is drilled on the axial isolation strip (4). The fluorescent layer (301) corresponds to the blind hole (401). An annular groove (402) is also drilled on the inner wall of the blind hole (401). A limiting unit is provided in the blind hole (401). The limiting unit includes a pre-push layer (51) located at the bottom of the blind hole (401) and a T-shaped adhesive layer (52) wrapped around the fluorescent layer (301). The T-shaped adhesive layer (52) extends into the annular groove (402).

7. A cross-linked polyethylene insulated flame-retardant control cable according to claim 6, characterized in that: The pre-push layer (51) is made of high-temperature resistant elastic material and is in a compressed state. The length of the pre-push layer (51) when it is not under compressive force is greater than the depth of the blind hole (401).

8. A cross-linked polyethylene insulated flame-retardant control cable according to claim 7, characterized in that: The T-shaped adhesive layer (52) is also made of hot melt material, and the melting point of the T-shaped adhesive layer (52) is higher than that of the pre-melted layer (302).

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