A pipeline with leak self-awareness function and preparation method

Abstract

The embodiment of the present application provides a pipeline with leakage self-awareness function and a preparation method, which is characterized by the following: an outer functional awareness layer with wrapped microcapsules of color developing agent is coated outside the composite adhesive layer. When the liquid transported in the composite adhesive layer leaks, the exuded liquid will act on the microcapsules in the outer functional awareness layer to make them absorb liquid and swell and generate extrusion pressure. When the extrusion pressure reaches a preset threshold, the microcapsules will rupture and release the internal wrapped color developing agent. After the color developing agent contacts with the air, a color developing reaction will occur, thereby directly showing the occurrence and specific point of the leakage. This scheme can realize online real-time awareness and accurate positioning of small hidden leakage of the pipeline without relying on manual inspection. At the same time, it does not need to add additional tracer reagent in the cooling liquid, thereby avoiding the use restriction of the additive in the new standard of the cooling liquid, being able to adapt to the composition requirement of the new generation of cooling liquid, and having excellent detection compatibility and long-term awareness ability.

Description

Technical Field

[0001] This invention relates to the field of vehicle thermal management system leak detection technology, and in particular to a pipeline with leak self-sensing function and its preparation method. Background Technology

[0002] With the rapid development of technology, the operating standards of thermal management systems for new energy vehicles are constantly improving. In the existing technology, physical detection and fluorescence tracing methods are generally used to detect coolant leaks in rubber hoses. Physical detection relies on manual inspection, which makes it difficult to detect small and hidden leaks and cannot achieve online monitoring. Although fluorescence tracing method has high sensitivity and accurate positioning, its compatibility and durability are difficult to adapt to the requirements of the new generation of coolants due to the restrictions on the use of additives in the new coolant standards. Summary of the Invention

[0003] In view of the above problems, embodiments of the present invention are proposed to provide a pipeline with leakage self-sensing function and a preparation method that overcomes or at least partially solves the above problems.

[0004] In a first aspect, embodiments of the present invention provide a pipeline with a leakage self-sensing function, comprising: Composite adhesive layer; An external functional sensing layer is formed by coating the composite adhesive layer. Microcapsules are distributed in the external functional sensing layer, and the microcapsules encapsulate a color developer. When the liquid in the composite adhesive layer leaks, the external functional sensing layer absorbs the liquid and swells, exerting a compressive force on the microcapsules distributed in the external functional sensing layer; when the compressive force reaches a preset threshold, the microcapsules rupture to release the color developer in the microcapsules, and a color reaction occurs.

[0005] Optionally, the composite adhesive layer includes: Inner adhesive layer; A braided reinforcement layer is wrapped around the inner adhesive layer; An intermediate transition layer covers the braided reinforcement layer.

[0006] Optionally, the matrix material of the external functional sensing layer is a hydrophilic modified rubber material, which is used to absorb liquid and swell after contact with the liquid.

[0007] Optionally, the hydrophilic modified rubber material is a hydrophilic modified EPDM rubber containing polar graft groups.

[0008] Optionally, the areal density of the microcapsules in the external functional sensing layer is 500 to 2000 capsules / cm².

[0009] Optionally, the microcapsule includes a shell and an inner cavity formed by the shell; The outer shell is used to enclose the color developer in the inner cavity, and to release the color developer in the inner cavity when the extrusion pressure reaches a preset threshold.

[0010] Optionally, the outer shell is made of resin material and has a wall thickness of 0.5 to 2.0 μm.

[0011] Secondly, the present invention also discloses a method for preparing a pipeline with a leakage self-sensing function, comprising: Forming a composite adhesive layer; Under a first preset temperature condition, raw rubber and filler are mixed evenly using a two-roll mill to obtain a mixed rubber compound; microcapsules containing color developer are added to the mixed rubber compound using a low-speed thin-pass method for further mixing to obtain a compounded rubber; The compounded rubber is extruded through an extruder at a second preset temperature and coated onto the outside of the composite rubber layer to form an external functional sensing layer.

[0012] Optionally, forming the composite adhesive layer includes: The mixed rubber compound is extruded using an extruder to obtain the inner rubber layer; A braided reinforcement layer is obtained by braiding the outer layer of the inner rubber layer using a braiding machine; An intermediate transition layer is formed outside the braided reinforcement layer.

[0013] Optionally, the first preset temperature condition is less than or equal to 100°C, and the second preset temperature condition is less than or equal to 90°C.

[0014] The embodiments of the present invention have the following advantages: This invention discloses a pipeline with leak-sensing functionality and its preparation method. It utilizes an external functional sensing layer coated with microcapsules containing a colorimetric reagent. When a leak occurs in the liquid transported within the composite adhesive layer, the seeping liquid acts on the microcapsules within the external functional sensing layer, causing them to absorb liquid, expand, and generate pressure. When the pressure reaches a preset threshold, the microcapsules rupture and release the encapsulated colorimetric reagent. Upon contact with air, the colorimetric reagent produces a color reaction, thus visually indicating the occurrence and specific location of the leak. This solution achieves online real-time sensing and precise location of minute, hidden leaks in pipelines without relying on manual inspections. Furthermore, it eliminates the need for additional tracer reagents in the coolant, circumventing the restrictions on additive use in new coolant standards. It is compatible with the composition requirements of next-generation coolants and possesses excellent detection compatibility and long-lasting sensing capabilities. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0016] Figure 1 This is a structural block diagram of a pipeline with leakage self-sensing function provided in an embodiment of the present invention; Figure 2 This is a structural block diagram of another pipeline with leakage self-sensing function provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a microcapsule provided in an embodiment of the present invention; Figure 4 This is a flowchart of the steps in preparing a pipeline with leakage self-sensing function according to an embodiment of the present invention. 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, 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.

[0018] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0019] One of the core concepts of this invention is that by coating a composite adhesive layer with microcapsules containing a colorimetric agent, when a leak occurs in the liquid transported inside the composite adhesive layer, the seeping liquid acts on the microcapsules in the external functional sensing layer, causing them to absorb liquid, expand, and generate pressure. When the pressure reaches a preset threshold, the microcapsules rupture and release the colorimetric agent inside. The colorimetric agent reacts with air to produce a colorimetric reaction, thus visually indicating the occurrence and specific location of the leak. This solution can achieve online real-time sensing and precise location of minor, hidden leaks in pipelines without relying on manual inspections. At the same time, it does not require the addition of additional tracer reagents to the coolant, thus avoiding the restrictions on the use of additives in the new coolant standards. It can adapt to the composition requirements of the new generation of coolants and has excellent detection compatibility and long-term sensing capabilities.

[0020] Reference Figure 1 The diagram illustrates a structural block diagram of a pipeline with a leakage self-sensing function according to an embodiment of the present invention, which may include: Composite adhesive layer 101; An external functional sensing layer 102 is coated on the outside of the composite adhesive layer. Microcapsules 1021 are distributed on the external functional sensing layer. The microcapsules encapsulate a color developer. When the liquid in the composite adhesive layer leaks, the external functional sensing layer 102 absorbs the liquid and swells to generate extrusion pressure. When the extrusion pressure reaches a preset threshold, the color developer in the microcapsules is released and a color reaction occurs.

[0021] In this embodiment of the invention, the liquid transported in the pipeline can be any liquid transported in various pipelines. This invention will be described using the coolant in the thermal management system of a new energy vehicle as an example.

[0022] The composite adhesive layer 101 is the main basic structure of the pipeline with leakage self-sensing function. As the bearing substrate of the pipeline, it undertakes the functions of fluid transportation and structural support. Its interior forms a complete fluid flow channel for transporting the circulating coolant in the thermal management system. Under normal pipeline operation, it can achieve internal coolant sealing and isolation, withstand the working pressure of the fluid inside the pipeline, and ensure the stable circulation of coolant in the thermal management circuit. At the same time, it provides a stable adhesion interface and structural support for the outer functional layer. It is an essential component of the pipeline's basic transportation performance and structural strength.

[0023] The external functional sensing layer 102 is coated on the outer surface of the composite adhesive layer 101 and is a functional layer that enables self-sensing of pipeline leaks. Several microcapsules 1021 containing a colorimetric agent are distributed within this layer. Under normal operating conditions with no pipeline leaks, the microcapsules maintain their intact capsule structure, the internal colorimetric agent is sealed, and the external functional sensing layer maintains its normal appearance. When the composite adhesive layer is damaged and the internal thermal management coolant leaks, the seeping coolant penetrates into the external functional sensing layer. The external functional sensing layer generates a liquid absorption and swelling effect, gradually forming a compressive force. As the amount of liquid absorbed increases and the degree of expansion intensifies, the compressive force continues to rise. When the compressive force reaches a preset threshold, the capsule wall ruptures, and the internally sealed colorimetric agent is released. The released colorimetric agent reacts with air, forming a colorimetric mark on the outer surface of the pipeline that can be directly identified by the naked eye. This visually indicates the occurrence and specific location of the leak, enabling online visual sensing and location of pipeline leaks without the need for additional detection equipment or manual inspection.

[0024] This invention discloses a pipeline with a leak-sensing function. By coating a composite adhesive layer with microcapsules encapsulating a colorimetric agent, when a leak occurs in the liquid transported inside the composite adhesive layer, the seeping liquid acts on the microcapsules in the outer functional sensing layer, causing them to absorb liquid, expand, and generate extrusion pressure. When the extrusion pressure reaches a preset threshold, the microcapsules rupture and release the encapsulated colorimetric agent. The colorimetric agent reacts with air to produce a colorimetric reaction, thus visually indicating the occurrence and specific location of the leak. This solution can achieve online real-time sensing and precise location of minor, hidden leaks in pipelines without relying on manual inspection. At the same time, it does not require the addition of additional tracer reagents to the coolant, circumventing the restrictions on the use of additives in the new coolant standards. It can adapt to the composition requirements of the new generation of coolants and has excellent detection compatibility and long-term sensing capability.

[0025] In one embodiment of the present invention, the composite adhesive layer includes: Inner adhesive layer; A braided reinforcement layer is wrapped around the inner adhesive layer; An intermediate transition layer is wrapped around the braided reinforcement layer.

[0026] In embodiments of the present invention, such as Figure 1 The composite adhesive layer 101 includes: an inner adhesive layer 1011; a braided reinforcement layer 1012 covering the inner adhesive layer 1011; and an intermediate transition layer 1013 covering the braided reinforcement layer 1012.

[0027] The inner rubber layer 1011, located at the innermost edge of the composite rubber layer 101, is a sealing layer that directly contacts the coolant transported inside the pipeline. It bears the most basic functions of fluid isolation and media resistance, serving as the first barrier to prevent internal leakage of the coolant and maintain normal circulation in the thermal management circuit. During long-term pipeline operation, the inner rubber layer needs to continuously withstand the chemical erosion of the coolant, fluctuations in operating temperature, and the scouring effect of the fluid. Simultaneously, it must possess good elasticity and flexibility to adapt to the bending installation of the pipeline and the vibration conditions of vehicle operation, preventing leaks. To address issues such as cracking, hardening, and swelling, the inner rubber layer of automotive thermal management pipes typically uses ethylene propylene diene monomer (EPDM) rubber as the main substrate. This material possesses excellent resistance to ethylene glycol coolant, high and low temperature resistance, and aging resistance, and can operate stably for extended periods within a wide temperature range of -40℃ to 150℃. Furthermore, by mixing and adjusting the formula with additives such as carbon black, zinc oxide, antioxidants, and plasticizers, its wear resistance, tear resistance, and long-term sealing reliability can be further improved, making it suitable for the stringent operating requirements of thermal management systems in new energy vehicles.

[0028] The braided reinforcement layer 1012 is wrapped around the outer side of the inner rubber layer 1011. It primarily bears the circumferential and axial stresses caused by the internal fluid pressure of the pipeline, directly determining the pipeline's pressure-bearing capacity, resistance to pulse fatigue, and overall structural strength. During the operation of the thermal management system, coolant pressure fluctuations and vibrations from vehicle movement exert continuous mechanical loads on the pipeline. The braided reinforcement layer, through its interwoven fiber structure, disperses and bears these loads, limiting radial deformation and preventing failures such as bulging, bursting, and tensile fracture. Simultaneously, it enhances structural strength while retaining the pipeline's bending flexibility. To meet the complex piping layout and installation requirements of the entire vehicle, the braided reinforcement layer 1012 can be made of high-strength synthetic fibers through a braiding process. Commonly used materials include polyester fibers, polyamide fibers, and high-performance aramid fibers. Among them, polyester fibers have excellent cost performance and good adhesion compatibility with rubber substrates, making them the mainstream choice for conventional automotive cooling pipes. Aramid fibers have higher specific strength and better temperature resistance, making them suitable for high-pressure, high-load high-end thermal management pipes. Under some special high-pressure conditions, copper-plated steel wire can also be used as a reinforcing material to further improve the burst pressure and deformation resistance of the pipes.

[0029] The intermediate transition layer 1013 covers the outer side of the braided reinforcement layer 1012 and is the outermost structure of the composite adhesive layer 101. It also serves as the connecting layer between the composite adhesive layer and the outer functional sensing layer. Its function is to optimize interlayer adhesion, fill the pores of the braided layer, and form a uniform and flat external adhesion substrate. Because the braided reinforcement layer has a fiber interwoven structure with numerous pores and uneven textures on its surface, directly covering the outer functional adhesive layer can easily lead to weak interlayer adhesion and delamination. The intermediate transition layer can fully impregnate and fill the fiber gaps in the braided layer during the molding process, completely covering the braided reinforcement layer to form a continuous and flat rubber interface. This not only improves the interlayer bonding force within the composite adhesive layer, preventing interlayer delamination during bending, pressure, and vibration of the pipeline, but also... This provides a stable and continuous adhesion base for the outer functional sensing layer, ensuring the uniformity of microcapsule distribution and long-term adhesion stability within the outer functional sensing layer. Simultaneously, this layer also serves as an auxiliary sealing barrier. When minor damage occurs in the inner rubber layer or a small amount of coolant leaks out, it slows the outward diffusion of the liquid, allowing the leaked liquid to act more evenly on the outer functional sensing layer, ensuring the sensitivity and accuracy of leakage detection. In terms of material selection, the intermediate transition layer can typically use EPDM rubber compound, consistent with the inner rubber layer substrate, ensuring compatibility with the inner rubber layer and woven fibers. Furthermore, the viscosity and flowability of the rubber compound can be adjusted according to molding process requirements, allowing it to better wet the woven layer structure during vulcanization and achieve optimal interlayer bonding.

[0030] like Figure 2 The diagram shows a structural block diagram of another pipeline with leakage self-sensing function provided by an embodiment of the present invention. The pipeline may include an inner adhesive layer 1011; a braided reinforcement layer 1012 covering the inner adhesive layer 1011; an intermediate transition layer 1013 covering the braided reinforcement layer 1012; and an outer functional sensing layer 102 covering the outer surface of the intermediate transition layer 1013.

[0031] In one embodiment of the present invention, the matrix material of the external functional sensing layer is a hydrophilic modified rubber material, which is used to absorb liquid and swell after contact with liquid.

[0032] In this embodiment of the invention, the external functional sensing layer can be made of hydrophilic modified rubber material as the substrate for carrying microcapsules. This substrate is obtained by introducing hydrophilic properties through molecular modification or component blending on the basis of conventional rubber matrix. It retains the elasticity, aging resistance and interlayer adhesion compatibility of the rubber material itself, and has the ability to actively adsorb and absorb water-based liquids. It is the core structural basis for realizing leakage triggering and swelling to break the microcapsules.

[0033] The hydrophilic modified rubber matrix and the inner composite rubber layer have the same material system and vulcanization compatibility. During the co-vulcanization process of the pipeline, a strong interlayer bonding interface can be formed, avoiding interlayer peeling and detachment during vehicle driving vibration and pipeline bending deformation. It can also inherit the wide temperature range service, coolant corrosion resistance and long-term aging resistance of rubber materials, ensuring the stability and reliability of the leak self-sensing function throughout the entire life cycle of the new energy vehicle thermal management system. In addition, relying on the overall hydrophilic liquid absorption and swelling effect of the matrix, the volume change under small leaks can be amplified, improving the trigger sensitivity for micro and hidden leaks. Sufficient extrusion pressure can be generated to trigger color development without large flow leaks, further enhancing the detection accuracy of online self-sensing.

[0034] In one embodiment of the present invention, the hydrophilic modified rubber material is a hydrophilic modified EPDM rubber containing polar graft groups.

[0035] In this embodiment of the invention, the hydrophilic modified rubber material used in the external functional sensing layer can specifically be hydrophilic modified ethylene propylene diene monomer (EPDM) grafted with polar graft groups. This material uses EPDM, commonly used in automotive piping, as its base material. While fully retaining the original performance advantages of EPDM, it is endowed with stable hydrophilic liquid absorption capacity through molecular grafting modification. Conventional EPDM is copolymerized from ethylene, propylene, and non-conjugated dienes. Its molecular backbone has a saturated non-polar structure and possesses excellent resistance to high and low temperature aging, resistance to ethylene glycol coolant corrosion, ozone resistance, and weather resistance. It is the mainstream base material for automotive rubber piping. However, due to its extremely low molecular chain polarity and overall strong hydrophobic properties, it cannot actively adsorb water. Water-based coolants are difficult to use directly as the substrate for leak sensing layers. By introducing polar hydrophilic graft groups such as hydroxyl, carboxyl, sulfonic acid, and polyoxyethylene ether segments onto the molecular side chains of EPDM through graft modification, the hydrophobic rubber matrix can gain the ability to actively adsorb and store water-based liquids through hydrogen bonding and molecular adsorption between the polar groups and water molecules. Moreover, graft modification only introduces functional groups into the molecular side chains and does not destroy the saturated structure of the EPDM main chain, thus maximizing the preservation of the original mechanical elasticity, media resistance, and long-term aging resistance of the substrate.

[0036] When the thermal management coolant seeps out from the damaged area of ​​the composite adhesive layer and penetrates into the outer functional sensing layer, the polar graft groups in the hydrophilic modified EPDM matrix can actively capture and adsorb water molecules in the coolant, causing the liquid to gradually penetrate into the rubber matrix and induce volume swelling. As the amount of liquid absorbed continues to increase, the degree of matrix swelling continuously increases, thereby forming a uniform and gradually increasing extrusion pressure on the dispersed microcapsules within the layer. When the extrusion pressure reaches the preset rupture threshold of the microcapsule wall, the capsule wall can be ruptured to release the colorimetric agent, triggering a colorimetric reaction to complete the visual perception of the leak. At the same time, the hydrophilic modified EPDM and the conventional EPDM substrate of the composite adhesive layer belong to the same rubber system, and can form a strong interlayer interface with chemical bonding during the co-vulcanization molding process of the pipeline, avoiding interlayer peeling and detachment under pipeline bending and vehicle vibration conditions. Its resistance to coolant corrosion and resistance to wide temperature fluctuations also match the service requirements of the entire life cycle of the vehicle's thermal management system, which can not only stably realize the swelling triggering effect under minor leaks, but also ensure the structural reliability and functional stability of the outer functional sensing layer during long-term service.

[0037] In one embodiment of the present invention, the areal density of microcapsules in the outer functional sensing layer is 500 to 2000 capsules / cm².

[0038] In this embodiment of the invention, the areal density of microcapsules in the outer functional sensing layer can be set to 500 to 2000 capsules / cm², that is, 500 to 2000 microcapsules encapsulating colorimetric agents are uniformly dispersed in the effective area of ​​the outer functional sensing layer per square centimeter. This parameter range is a design index determined by comprehensively balancing leakage detection sensitivity, point location accuracy, matrix mechanical reliability and manufacturing cost, and is adapted to the leakage detection requirements of thermal management pipelines in new energy vehicles.

[0039] In practical applications, the areal density can be flexibly adjusted within this range according to the operating conditions of different thermal management circuits. For scenarios such as power battery cooling circuits, which have high requirements for leakage sensitivity and small pipe diameters, a higher areal density can be selected to further enhance the detection accuracy and color clarity of minute leaks. For scenarios such as drive motor cooling circuits, which have higher pressure and larger pipe deformation, a lower areal density can be selected to ensure the overall structural mechanical performance and long-term service stability of the pipeline while ensuring the effectiveness of the self-sensing function of leakage.

[0040] In one embodiment of the present invention, the microcapsule 1021 includes a shell 10211 and an inner cavity 10212 formed by the shell 10211; the shell 10211 is used to encapsulate the color developer in the inner cavity 10212 and release the color developer in the inner cavity 10212 when the extrusion pressure reaches a preset threshold.

[0041] In embodiments of the present invention, such as Figure 3The diagram shows a microcapsule provided in an embodiment of the present invention. The outer shell 10211 is a sealed encapsulation structure of the microcapsule. The outer shell 10211 can form an inner cavity 10212. The outer shell 10211 can encapsulate the color developer in the inner cavity 10212.

[0042] The outer shell 10211 is usually made of a high-molecular polymer wall material with excellent temperature resistance and mechanical stability. Thermosetting cross-linked resins such as urea-formaldehyde resin and melamine-formaldehyde resin can be used, or modified gelatin-gum arabic composite wall material can be used. The burst strength of this type of material can be set by adjusting the degree of polymerization, cross-linking density and shell thickness. The color developer in the inner cavity 10212 can be released when the pressure reaches a preset threshold.

[0043] It should be noted that the color developing agent can be one of methylene blue, leuco malachite green, or leuco crystal violet, or other color developing agents that can react with air. The specific type is not limited here.

[0044] During normal pipeline operation, the color developer is always sealed and isolated by the outer shell 10211, preventing it from reacting with external air or the rubber matrix, and preventing performance degradation due to pipeline temperature fluctuations or vibration impacts. This ensures the long-term activity and stability of the color developer, guaranteeing the lifespan of the leak detection function. Furthermore, since the color developer is entirely encapsulated within microcapsules on the pipe wall, it does not need to be added to the coolant, completely circumventing the restrictions on additives in the new coolant standard and making it compatible with the formulation requirements of the new generation of low-additive, low-conductivity coolants.

[0045] In one embodiment of the present invention, the outer shell is made of resin material and has a wall thickness of 0.5 to 2.0 μm.

[0046] In this embodiment of the invention, the outer shell of the microcapsule can be made of resin-based polymer materials, and the wall thickness can be controlled within the range of 0.5 to 2.0 μm. This combination of material and wall thickness is a guarantee for achieving precise control of the mechanical threshold of the microcapsule while taking into account both functional reliability and processability.

[0047] The resin material used as the outer shell can typically be a thermosetting resin such as urea-formaldehyde resin or melamine-formaldehyde resin. These materials have excellent molding processability and mechanical adjustability. They can form a dense and continuous encapsulation structure on the surface of the core material through processes such as in-situ polymerization. This allows the core material to withstand coolant erosion, temperature cycling fluctuations, and aging during the operation of the vehicle's thermal management system, maintaining the long-term stability of the capsule wall structure and mechanical properties, and ensuring the sealing and preservation effect of the colorant inside the core material.

[0048] In practical design, the target rupture pressure can be flexibly matched within this range by adjusting the crosslinking density and wall thickness parameters of the resin. This makes the rupture threshold of the capsule wall higher than the peak value of vibration and structural stress under normal pipeline conditions, and lower than the extrusion pressure generated by matrix swelling when leaking. This ensures both structural integrity and sealing reliability under leak-free conditions, and also ensures that color development can be accurately triggered when a leak occurs, achieving a stable leak self-sensing effect.

[0049] In one embodiment of the present invention, the rupture pressure threshold of the microcapsule wall needs to be higher than all conventional vibration and structural stress levels under normal pipeline operating conditions, while being lower than the effective extrusion pressure generated when the hydrophilic modified rubber matrix of the outer functional sensing layer leaks and swells. This achieves the triggering logic of rupture of the capsule wall and release of the color developer only when the coolant leaks and causes the matrix to swell, thus avoiding the problem of false triggering and false alarm under normal operating conditions from the root of the mechanical mechanism.

[0050] During the normal operation of the thermal management pipeline in new energy vehicles, the pipeline continuously withstands various conventional mechanical loads, including continuous vibration and impact stress from road surface excitation during vehicle operation, circumferential deformation stress caused by fluctuations in the working pressure of the coolant inside the pipeline, residual bending stress from the vehicle layout and installation, and thermal stress generated by the thermal expansion and contraction of the rubber matrix under hot and cold cycling conditions. These conventional loads exert a certain degree of compression on the microcapsules within the outer functional sensing layer. If the microcapsule rupture pressure threshold is lower than the peak level of these conventional stresses, unexpected rupture of the capsule wall may occur during normal, leak-free operation, leading to the unexplained release of the colorimetric agent and false alarms, interfering with the accuracy of leak detection. Therefore, the rupture pressure threshold needs to be set higher than the maximum value of all normal operating stresses, with a reasonable safety margin reserved to ensure that the microcapsule maintains its structural integrity and the colorimetric agent remains sealed during normal vehicle operation under all conditions, pipeline pressure, and temperature fluctuations. However, when the composite adhesive layer... When the coolant leaks and penetrates the outer functional sensing layer, the hydrophilic modified rubber matrix absorbs the coolant and undergoes continuous volume swelling. As the amount of liquid absorbed increases, a stable and continuously increasing extrusion pressure is gradually formed on the microcapsule. Setting the rupture pressure threshold below the peak level of this swelling extrusion pressure ensures that when the matrix swelling reaches the trigger condition corresponding to the leakage amount, the extrusion pressure can stably break through the strength limit of the capsule wall, causing the microcapsule to rupture in an orderly manner and release the internal colorant. This color reaction with air provides feedback on the occurrence and specific location of the leak. This threshold matching design, through precise control of the mechanical boundary, strictly limits the trigger condition of the microcapsule to the sole working condition of matrix swelling and extrusion caused by leakage. This not only ensures the reliability of the leak detection response but also eliminates the risk of false alarms caused by factors such as normal vibration, pressure fluctuations, and temperature changes from the structural design level. This improves the accuracy and reliability of the online leak detection of this self-sensing pipeline and meets the long-term stable operation requirements of the thermal management system of new energy vehicles.

[0051] This invention discloses a pipeline with a leak-sensing function. By coating a composite adhesive layer with microcapsules encapsulating a colorimetric agent, when a leak occurs in the liquid transported inside the composite adhesive layer, the seeping liquid acts on the microcapsules in the outer functional sensing layer, causing them to absorb liquid, expand, and generate extrusion pressure. When the extrusion pressure reaches a preset threshold, the microcapsules rupture and release the encapsulated colorimetric agent. The colorimetric agent reacts with air to produce a colorimetric reaction, thus visually indicating the occurrence and specific location of the leak. This solution can achieve online real-time sensing and precise location of minor, hidden leaks in pipelines without relying on manual inspection. At the same time, it does not require the addition of additional tracer reagents to the coolant, circumventing the restrictions on the use of additives in the new coolant standards. It can adapt to the composition requirements of the new generation of coolants and has excellent detection compatibility and long-term sensing capability.

[0052] Reference Figure 4 The diagram illustrates a flowchart of the steps involved in preparing a pipeline with a leak-sensing function according to an embodiment of the present invention, which may include: Step 201: Form a composite adhesive layer.

[0053] In this embodiment of the invention, the prepared rubber compound can be processed into a tubular structure with uniform diameter and stable wall thickness through rubber extrusion molding process. This enables the composite rubber layer to resist the corrosion of coolant media, withstand the internal working pressure of the pipeline, and adapt to the bending conditions of vehicle installation. At the same time, it forms a flat and continuous outer surface, providing a stable bonding interface for the subsequent coating of the external functional sensing layer and ensuring the reliability of the interlayer bonding.

[0054] Step 202: Under the first preset temperature condition, the raw rubber and filler are mixed evenly using a two-roll mill to obtain a mixed rubber compound; microcapsules containing color developer are added to the mixed rubber compound using a low-speed thin-pass method for mixing to obtain a compounded rubber.

[0055] In this embodiment of the invention, the first preset temperature is a process temperature range suitable for plasticizing and mixing raw rubber. The temperature setting needs to take into account the plasticizing fluidity of the raw rubber, while preventing the rubber compound from undergoing vulcanization crosslinking too early due to heating, and also avoiding premature damage to the microcapsule shell due to excessively high temperature.

[0056] First, the selected base raw rubber is fed into the gap between the rollers of the open mill. The raw rubber is plasticized by the relative rotation of the two rollers of the open mill and the shearing and crushing action of the rollers. Then, various fillers are gradually added into the open mill. The fillers generally include reinforcing fillers, processing aids, antioxidants and other components. Through repeated shearing and turning by the rollers, the various fillers are evenly dispersed into the raw rubber matrix, eliminating the phenomenon of filler agglomeration and lumps, and allowing the components to be fully impregnated and blended, finally obtaining a mixed rubber compound with uniformly dispersed components.

[0057] After the raw rubber and filler are mixed, the process needs to be switched to a low-speed thin-pass operation mode. The speed of the open mill rollers is reduced, and the roller gap is narrowed. Microcapsules containing color developers are slowly added to the mixed rubber compound. The rubber compound is repeatedly passed through the narrow roller gap to complete the thin-pass process. Relying on the relatively gentle rolling and tumbling action, the microcapsules are dispersed inside the rubber matrix of the mixed rubber compound, preserving the integrity of the microcapsule shell to the greatest extent and preventing the microcapsules from breaking prematurely. After multiple low-speed thin-pass mixing processes, the microcapsules are evenly dispersed in the rubber matrix, and finally a compound rubber that can be used for subsequent extrusion processing is obtained. The compound rubber contains a large number of microcapsules that completely encapsulate the color developer. When a medium leaks into the rubber layer, it will break the microcapsule shell and release the color developer, realizing the basic function of leakage color detection.

[0058] Step 203: The compound rubber is extruded through an extruder at a second preset temperature to coat the outside of the composite rubber layer, forming an external functional sensing layer.

[0059] In this embodiment of the invention, the second preset temperature is the processing temperature of each section of the extruder barrel and the die head. This temperature needs to match the extrusion rheological characteristics of the compound to ensure that the compound has suitable melt flow properties and that the extrusion molding is smooth.

[0060] The compound obtained in the previous step is fed into the feed end of the extruder. The compound is conveyed forward by the extruder screw under the action of conveying, shearing and plasticizing. It is heated and plasticized in the barrel to become a continuously molten rubber material. The molten rubber material is extruded through the annular die head adapted to the tubular coating of the extruder to form an annular cylindrical rubber material preform. The annular die head is coaxially sleeved on the outside of the already formed composite rubber layer. The extruded cylindrical rubber material continuously coats the outer circumferential wall of the composite rubber layer, realizing a tight fit between the two layers. During the coating process, the extrusion rate and traction speed are controlled to match each other to ensure that the thickness of the coated rubber layer is uniform and consistent, without molding defects such as local material shortage, bulges, or wrinkles. After the coating is completed, this layer is cured and formed into the outer functional sensing layer. The outer functional sensing layer is closely attached to the outer surface of the composite rubber layer and together with the inner composite rubber layer, it forms a complete pipeline wall.

[0061] In one embodiment of the present invention, forming a composite adhesive layer includes: extruding a mixed adhesive compound through an extruder to obtain an inner adhesive layer; weaving the inner adhesive layer with a braiding machine to obtain a braided reinforcing layer; and forming an intermediate transition layer outside the braided reinforcing layer.

[0062] In this embodiment of the invention, the inner adhesive layer is the innermost layer of the composite adhesive layer. It is a functional layer that directly contacts the pipeline transport medium and mainly plays the roles of sealing the medium, blocking fluid, preventing corrosion, and preventing leakage.

[0063] In the preparation process, a rubber compound suitable for pipeline transportation conditions is first selected. The pretreated compound is fed into the extruder at a uniform speed. With the help of the extruder screw's conveying, shearing, and plasticizing action, the solid rubber compound is transformed into a uniform molten rubber compound. Then, it is continuously extruded through a special tubular extruder head to form a tubular inner rubber layer preform with uniform wall thickness, regular roundness, and a dense and smooth surface. This process requires control of the extrusion process parameters to ensure that there are no molding defects such as bubbles, cracks, and voids inside the inner rubber layer, that the pipe wall thickness is uniform, and that the overall structure is continuous and complete. This effectively blocks the penetration of the transported medium inside the pipeline and prevents the medium from overflowing prematurely. At the same time, it provides a stable base support for the subsequent overlay molding of the braided reinforcement layer.

[0064] After the inner rubber layer is extruded and pre-shaped, the continuously conveyed tubular inner rubber layer is used as the base material and a braiding machine is used for overall braiding. A dense braided reinforcement layer is uniformly wrapped around the outer surface of the inner rubber layer, which greatly improves the overall structural strength, pressure resistance, and tensile strength of the pipeline. In actual processing, high-strength fibers, polyester, nylon, or steel wire can be selected according to the pressure level and usage scenario of the pipeline. The braiding density, braiding angle, and travel speed of the braiding machine are adjusted to ensure that the wires are evenly distributed, the warp and weft are tightly interwoven, and there are no defects such as skipped threads, broken wires, uneven density, or local stacking. During the braiding process, the inner rubber layer is kept at a uniform and stable traction and conveyance, so that the braided wires are tightly attached to the outer surface of the inner rubber layer to form a fully covered mesh structure. This mesh reinforcement layer can effectively disperse the stress of the pipeline under pressure, avoid the problem of easy deformation and cracking of the pure rubber inner rubber layer under pressure, improve the tensile and torsional resistance of the pipeline, and give the composite rubber layer excellent structural stability, making it suitable for high-pressure and complex working conditions.

[0065] The intermediate transition layer is a transitional structure that connects the braided reinforcement layer and the subsequent external functional sensing layer. During the molding process, integrated processes such as extrusion coating and roll coating can be used to uniformly coat and apply the appropriate transition layer adhesive to the outer surface of the braided reinforcement layer, so that the adhesive can fully penetrate and fill the mesh gaps of the braided wire, completely wrapping the braided reinforcement layer and forming a smooth and dense elastic transition adhesive layer.

[0066] In one embodiment of the present invention, the first preset temperature condition is less than or equal to 100°C, and the second preset temperature condition is less than or equal to 90°C.

[0067] In this embodiment of the invention, the first preset temperature is controlled to not exceed 100°C during the mixing stage of the open mill. This can suppress premature cross-linking and vulcanization of the raw rubber due to frictional heat during the shearing and mixing process. At the same time, it can prevent the microcapsule shell from softening, melting, or rupturing due to excessively high temperatures, and prevent the colorant inside the capsule from being released prematurely during the mixing stage, which would cause the leakage detection function to fail.

[0068] When the extruder extrudes the outer functional sensing layer, the second preset temperature is controlled at less than or equal to 90°C. This temperature is lower than the upper limit of the open mill stage. Considering that the extruder screw has a continuous shearing effect on the rubber material, which will further generate shear heat, the rubber material stays in the barrel for a relatively longer time. A lower temperature threshold can reduce the thermal damage to the microcapsule body caused by the long-term thermal environment, and ensure that the microcapsule remains intact after the outer functional sensing layer is formed, and the colorant is properly encapsulated inside the capsule.

[0069] This invention discloses a method for preparing a pipeline with a leak-sensing function. By coating a composite adhesive layer with microcapsules containing a colorimetric agent distributed on the outside, when a leak occurs in the liquid transported inside the composite adhesive layer, the seeping liquid acts on the microcapsules in the outer functional sensing layer, causing them to absorb liquid, expand, and generate extrusion pressure. When the extrusion pressure reaches a preset threshold, the microcapsules rupture and release the encapsulated colorimetric agent. The colorimetric agent reacts with air to produce a colorimetric reaction, thus visually indicating the occurrence and specific location of the leak. This solution can achieve online real-time sensing and precise location of minor, hidden leaks in pipelines without relying on manual inspection. At the same time, it does not require the addition of additional tracer reagents to the coolant, circumventing the restrictions on the use of additives in the new coolant standards, and can adapt to the composition requirements of the new generation of coolants, possessing excellent detection compatibility and long-term sensing capabilities.

[0070] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0071] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0072] Finally, 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 terminal device 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 terminal device. 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 terminal device that includes the element.

[0073] The present invention has provided a detailed description of a pipeline with leakage self-sensing function and its preparation method. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A pipeline with a leak-sensing function, characterized in that, include: Composite adhesive layer; An external functional sensing layer is formed by coating the composite adhesive layer, and microcapsules are distributed in the external functional sensing layer, with each microcapsule containing a color developer. When the liquid in the composite adhesive layer leaks, the external functional sensing layer absorbs the liquid and swells, exerting a compressive force on the microcapsules distributed in the external functional sensing layer; when the compressive force reaches a preset threshold, the microcapsules rupture to release the color developer in the microcapsules, and a color reaction occurs.

2. The pipeline with leakage self-sensing function according to claim 1, characterized in that, The composite adhesive layer includes: An inner adhesive layer is used to allow the liquid to flow through; A braided reinforcement layer is wrapped around the inner adhesive layer; An intermediate transition layer covers the braided reinforcement layer and is used to bond with the outer functional sensing layer.

3. The pipeline with leakage self-sensing function according to claim 1, characterized in that, The substrate material of the external functional sensing layer is a hydrophilic modified rubber material, which is used to absorb liquid and swell after contact with the liquid.

4. The pipeline with leakage self-sensing function according to claim 3, characterized in that, The hydrophilic modified rubber material is a hydrophilic modified EPDM rubber containing polar grafted groups.

5. The pipeline with leakage self-sensing function according to claim 1, characterized in that, The areal density of the microcapsules in the external functional sensing layer is 500 to 2000 capsules / cm².

6. The pipeline with leakage self-sensing function according to claim 1, characterized in that, The microcapsule includes an outer shell and an inner cavity formed by the outer shell; The outer shell is used to enclose the color developer in the inner cavity, and to release the color developer in the inner cavity when the extrusion pressure reaches a preset threshold.

7. The pipeline with leakage self-sensing function according to claim 6, characterized in that, The outer shell is made of resin material with a wall thickness of 0.5–2.0 μm.

8. A method for preparing a pipeline with a leak-sensing function, characterized in that, include: Forming a composite adhesive layer; Under a first preset temperature condition, raw rubber and filler are mixed evenly using a two-roll mill to obtain a mixed rubber compound; microcapsules containing color developer are added to the mixed rubber compound using a low-speed thin-pass method for further mixing to obtain a compounded rubber; The compounded rubber is extruded through an extruder at a second preset temperature and coated onto the outside of the composite rubber layer to form an external functional sensing layer.

9. The method for preparing a pipeline with leakage self-sensing function according to claim 8, characterized in that, The formation of the composite adhesive layer includes: The mixed rubber compound is extruded using an extruder to obtain the inner rubber layer; A braided reinforcement layer is obtained by braiding the outer layer of the inner rubber layer using a braiding machine; An intermediate transition layer is formed outside the braided reinforcement layer.

10. The method for preparing a pipeline with leakage self-sensing function according to claim 8, characterized in that, The first preset temperature condition is less than or equal to 100°C, and the second preset temperature condition is less than or equal to 90°C.

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