A method for manufacturing a flexible heat pipe and a flexible heat pipe

Abstract

The present application relates to a kind of preparation methods of flexible heat pipe and a kind of flexible heat pipe, and the method comprises: the cross section of flexible heat insulation section is circular, one end of evaporating section and one end of condensing section are respectively carried out round processing, then the wick is combined with one end of evaporating section and one end of condensing section, and form core body;Core body is sleeved in flexible heat insulation section, one end of flexible heat insulation section is respectively overlapped with one end of evaporating section and one end of condensing section and is sealed, and form a heat pipe body;One end of heat pipe body is sealed, then through the other end of heat pipe body completes vacuumizing, liquid injection procedure, then the other end is sealed.The method is by round processing, and flexible heat pipe can be composed of three sections with different cross sections, on the one hand, it is conducive to large-scale production and processing, and it is convenient to install and fix in practical application, on the other hand, it can greatly improve the heat transfer performance of flexible heat pipe, to meet the heat dissipation demand of the electronic device with small space and complex structure.

Description

Technical Field

[0001] This invention relates to the technical field of flexible heat pipe processing, and in particular to a method for preparing a flexible heat pipe and a flexible heat pipe. Background Technology

[0002] Flexible heat pipes possess excellent properties such as high thermal conductivity, flexibility, lightweight, and high stability. They can adapt to complex and confined installation spaces, achieving effective contact with the surfaces of complex-shaped electronic components. They play a crucial role, especially in solving heat dissipation problems for devices with relative motion, and are widely used in aerospace, electronics, defense technology, and many other fields. A flexible heat pipe consists of an evaporator end, a condenser end, and an adiabatic end (flexible section). It typically employs a "three-section" structure, using a metal corrugated pipe or a polymer flexible pipe connecting two metal sections as the shell.

[0003] Existing "three-section" flexible heat pipes all have circular cross-sections, such as patents CN209445862U "Flexible Heat Pipe" and CN105937861A "An Ultra-long Flexible Heat Pipe and Its Geothermal Snow Melting and De-icing Method". However, circular cross-section flexible heat pipes require high installation precision for ultra-thin, foldable, and highly integrated electronic devices; at the same time, there is often a large gap between the circular cross-section flexible heat pipe and the planar heat source, resulting in a large contact thermal resistance between the heat source and the heat pipe, which seriously affects the heat transfer effect of the heat pipe. In order to reduce the gap between the heat source and the heat pipe and improve the heat dissipation efficiency of the heat pipe, flat heat pipes or square heat pipes have been gradually developed and applied. Using a flattening process to press the circular heat pipe into a flat or square shape can effectively improve the heat transfer efficiency of the heat pipe. For example, patent CN105115334A "A Square Copper Heat Pipe Based on Internal Expansion and External Pressure and Its Manufacturing Method" uses a two-stage flattening process to transform the circular heat pipe into a square heat pipe. However, due to the flexibility requirements and structural limitations of flexible heat pipes, the flattening process is not suitable for manufacturing square or flat flexible heat pipes. Therefore, it is necessary to develop new encapsulation methods to prepare flexible heat pipes with an external contact plane to improve their heat transfer efficiency. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a method for preparing a flexible heat pipe and a flexible heat pipe. By rounding, the flexible heat pipe can be composed of three sections with different cross-sections. On the one hand, this facilitates large-scale production and processing and makes it easy to install and fix in practical applications. On the other hand, it can significantly improve the heat transfer performance of the flexible heat pipe, thereby meeting the heat dissipation needs of electronic devices with limited space and complex structures.

[0005] In a first aspect, the present invention provides a method for preparing a flexible heat pipe, comprising the following steps:

[0006] S1: Provide an evaporation section, a condensation section and a flexible insulation section, wherein the evaporation section and the condensation section are made of metal, the flexible insulation section is a metal corrugated pipe or a polymer flexible pipe, the sidewalls of the evaporation section and the condensation section are respectively provided with a plane for contacting the outside, and the cross-section of the flexible insulation section is circular or square.

[0007] S2: When the cross-section of the flexible insulation section is square, and the cross-sections of the evaporation section and the condensation section are also square, execute S4;

[0008] S3: When the cross-section of the flexible insulation section is circular, one end of the evaporation section and one end of the condensation section are respectively rounded, and then step S4 is executed;

[0009] S4: Combine the liquid absorption core with one end of the evaporation section and one end of the condensation section to form a core;

[0010] S5: The core is fitted into the flexible insulation section, one end of the flexible insulation section is overlapped and sealed with one end of the evaporation section, and the other end of the flexible insulation section is overlapped and sealed with one end of the condensation section to form a heat pipe body.

[0011] S6: Seal one end of the heat pipe body, then complete the vacuuming and liquid injection process through the other end of the heat pipe body, and then seal the other end.

[0012] The present invention discloses a method for preparing a flexible heat pipe. Through rounding, a three-section flexible heat pipe with different cross-sections can be realized. The cross-sections of the evaporation section, condensation section and flexible insulation section can be selected according to the needs of electronic devices with limited space and complex structures. This method can effectively reduce the difficulty of installation and fixation, and significantly improve the heat transfer performance of the flexible heat pipe. At the same time, this preparation method is also conducive to large-scale processing and production.

[0013] Furthermore, after sealing the other end of the heat pipe body, the following steps are also included:

[0014] A metal layer is deposited on the exterior of the heat pipe body using at least one of the following processes: magnetron sputtering, electroplating, or electroless plating.

[0015] The density of metal coatings is superior to that of commonly used polymer materials and adhesives, which helps to avoid micro-leakage problems in heat pipes and allows them to maintain a high vacuum level even after long-term use, thereby improving the airtightness and lifespan of heat pipes.

[0016] Furthermore, the liquid-absorbing core includes a first liquid-absorbing core and a second liquid-absorbing core; the first liquid-absorbing core is located inside the evaporation section and the condensation section, and adopts a capillary structure formed by sintering powder, porous wire mesh or woven tape; the second liquid-absorbing core is located inside the flexible insulation section, and adopts a porous wire mesh or woven tape, or a composite structure of porous wire mesh and woven tape; the first liquid-absorbing core and the second liquid-absorbing core are made of at least one of the following hydrophilic materials: copper, stainless steel, aluminum, titanium, nylon, carbon fiber, graphene, polypropylene.

[0017] The wick forms a crescent-shaped liquid surface inside the heat pipe that is easy to evaporate, and provides a sufficiently large capillary force for the condensed liquid to promote the return of the condensed liquid to the evaporation end. It can also maintain good performance when the heat pipe undergoes flexible deformation, and has properties such as corrosion resistance and impact resistance.

[0018] Furthermore, the inner diameter of the flexible insulation section is larger than the outer diameter of the evaporation section and the condensation section, and their fit tolerance is 0.1-0.5mm.

[0019] Furthermore, the flexible insulation section is sealed to the evaporation section and the condensation section using either adhesive bonding or low-temperature welding. Adhesive bonding is suitable for applications with low strength and low heat transfer, while low-temperature welding is suitable for heat dissipation of high-power, integrated electronic devices.

[0020] Furthermore, the liquid-absorbing core is combined with the evaporation section and the condensation section by high-temperature sintering or mechanical pressing. The liquid-absorbing core can be mechanically pressed into the flexible insulation section, or it can move freely within the flexible insulation section.

[0021] Furthermore, when the flexible insulation section is made of a polymer flexible tube, a spring is embedded inside. The embedded spring can prevent the flexible insulation section from collapsing during vacuuming and heat dissipation, and ensure a tight fit between the liquid-absorbing core and the tube body.

[0022] Furthermore, the cross-sections of the evaporation section and the condensation section are square, triangular, or flat. The cross-sections of the evaporation section and the condensation section can be selected according to the actual needs of the electronic device, further reducing the requirements for installation accuracy.

[0023] Secondly, the present invention also provides a flexible heat pipe, comprising a tube body closed at both ends and a working fluid located within the tube body; the tube body includes an evaporation section, a condensation section and a flexible insulation section, the two ends of the flexible insulation section overlapping one end of the evaporation section and one end of the condensation section respectively, the other ends of the evaporation section and the condensation section being sealed to form a closed heat pipe body; the sidewalls of the evaporation section and the condensation section each have a plane for contacting the outside, and the cross-section of the flexible insulation section is circular or square.

[0024] Furthermore, the cross-sections of the evaporation section and the condensation section are square or triangular, the cross-section of the flexible insulation section is circular, and the end of the evaporation section and the condensation section that overlaps with the flexible insulation section is rounded; or, the cross-sections of the evaporation section and the condensation section are square or flat, and the cross-section of the flexible insulation section is the corresponding square or flat.

[0025] This invention provides a method for fabricating a flexible heat pipe. This method involves rounding the evaporation and condensation sections, each with a flat surface contacting the outside, to overlap with a circular cross-section flexible insulating section. Therefore, it allows for the adaptation of three-section flexible heat pipes with different cross-sections to meet the actual needs of the internal structure of electronic devices. This helps reduce the difficulty of installation and fixation under complex operating conditions and significantly improves the heat dissipation effect of the heat pipe. Furthermore, a metal plating layer is deposited on the outside of the heat pipe body to improve its airtightness and extend its service life. The cross-sections of the evaporation and condensation sections can be square, triangular, or flat; the specific shape can be selected according to the actual needs of the internal structure of the electronic device, further reducing the requirements for installation accuracy.

[0026] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a flexible heat pipe that uses a circular cross-section polyimide tube as the flexible insulation section.

[0028] Figure 2 This is a schematic diagram of a square cross-section metal tube with one end rounded off.

[0029] Figure 3 This is a schematic diagram of a flexible heat pipe that uses a square cross-section polyimide tube as the flexible insulation section.

[0030] Figure 4 This is a schematic diagram of a flexible heat pipe that uses a metal corrugated tube as the insulation section.

[0031] Reference numerals: Evaporation section 1, Condensation section 2, Flexible insulation section 3, Liquid absorption core 4, Connector 5, Spring 6, Metal plating 7, First liquid absorption core 41, Second liquid absorption core 42. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0033] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0034] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0035] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0036] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0037] Example 1:

[0038] The structural schematic diagram of the flexible heat pipe described in this embodiment is shown below. Figure 1As shown in the figure, the flexible heat pipe includes a tube body sealed at both ends and a working fluid (not indicated in the figure) located inside the tube body. The tube body includes an evaporation section 1, a condensation section 2, a flexible insulation section 3, a wick 4, and a spring 6 located inside the flexible insulation section 3. The evaporation section 1 and condensation section 2 are copper tubes with a square cross-section. In other examples, the evaporation section 1 and condensation section 2 can also be made of other metal materials, such as aluminum, titanium, or stainless steel. The flexible insulation section 3 is a polyimide tube with a circular cross-section. In other examples, the flexible insulation section 3 can also be made of a metal corrugated tube or other flexible polymer materials, such as copper corrugated tubes, stainless steel corrugated tubes, titanium corrugated tubes, aluminum corrugated tubes, polyethylene (PE) tubes, polyurethane (PU) tubes, polyethylene terephthalate (PET) tubes, etc. The liquid-absorbing core 4 includes a first liquid-absorbing core 41 and a second liquid-absorbing core 42. The first liquid-absorbing core 41 is a copper powder sintered liquid-absorbing core located inside the evaporation section 1 and the condensation section 2. The second liquid-absorbing core 42 is a copper braided strip liquid-absorbing core located inside the flexible insulation section. In other examples, the first liquid-absorbing core can also be a capillary structure made of other powders, porous wire mesh or braided strips. The second liquid-absorbing core can also be a porous wire mesh, braided strip or a composite structure of porous wire mesh and braided strip made of other materials, such as stainless steel, aluminum, titanium, nylon, carbon fiber, graphene, polypropylene and other hydrophilic materials.

[0039] The square copper tube has a side length of 3mm and a length of 50mm. One end, approximately 15mm, is rounded, with an outer diameter of approximately 2.8mm (e.g., ...). Figure 2 (As shown). The circular polyimide tube has an inner diameter of 3mm and an outer diameter of 3.5mm. It is bonded to the rounded sections of the evaporation section 1 and the condensation section 2 using an adhesive bonding process to form joint 5. In this embodiment, Agilent Torr Seal high-vacuum sealant is used for sealing. In other examples, other adhesives or low-temperature welding processes can also be used for sealing.

[0040] The method for preparing the flexible heat pipe described in this embodiment is as follows:

[0041] S1: Provide two square-section copper tubes with a side length of 3mm and a length of 50mm. Round off one end of each copper tube. The rounded section is about 15mm long and about 2.8mm in outer diameter to form evaporation section 1 and condensation section 2.

[0042] S2: Insert a stainless steel core rod with a diameter of 1.5 mm into the copper tube. Fill the gap between the core rod and the copper tube with copper powder and copper braided tape of 300-400 mesh. Then, sinter at a high temperature of 900°C under the protection of 5% H2 atmosphere to make the core. The copper powder and copper braided tape are attached to the inner wall of the copper tube by sintering to form copper powder liquid-absorbing core 41 and copper braided tape liquid-absorbing core 42.

[0043] S3: The above-mentioned core is fitted into the polyimide tube. The two ends of the polyimide tube overlap with the rounded ends of the evaporation section 1 and the condensation section 1, respectively. The copper braided strip liquid-absorbing core 42 is inserted into the polyimide tube, and a spring 6 is inserted inside the polyimide tube. The spring 6 supports the polyimide tube to prevent the flexible insulation section 3 from collapsing during the vacuuming process. At the same time, the copper braided strip liquid-absorbing core 42 can be pressed and fixed to the inner wall of the flexible insulation section 3 to prevent the liquid-absorbing core from sliding.

[0044] S4: Agilent Torr Seal high vacuum sealant is used to reinforce the rounded end joints of the flexible insulation section 3 and the evaporation section 1 and the condensation section 2, forming joint 5;

[0045] S5: The port of condensing section 2 is shortened and sealed by inert gas shielded welding. Then, the heat pipe is evacuated and injected with liquid through the port of evaporating section 1. In this embodiment, pure water is used as the working fluid, and the amount of liquid injected is about 1.5 ml, accounting for 60% of the volume of the liquid absorber cavity. The vacuum degree is evacuated to 1 Pa or below. Then, the port of evaporating section 1 is sealed by cold welding and then sealed and reinforced by argon arc welding.

[0046] Example 2:

[0047] The structural schematic diagram of the flexible heat pipe described in this embodiment is shown below. Figure 3 As shown. In this embodiment, the evaporation section and condensation section are stainless steel tubes with square cross-sections; the flexible insulation section 3 is a polyurethane (PU) tube with a square cross-section and a wall thickness of 1 mm; the first liquid absorbent core 41 is a sintered liquid absorbent core with 3 layers of 250-mesh copper wire mesh, and the second liquid absorbent core 42 is a copper braided strip liquid absorbent core.

[0048] The first wicking core 41 is connected to the evaporation section 1, the condensation section 2, and the second wicking core 42 via a high-temperature sintering process to form a core body. The second wicking core 42 is located inside the flexible insulation section 3 and can move freely within it. In this embodiment, the evaporation section 1, the condensation section 2, and the flexible insulation section 3 all have square cross-sections, so no rounding treatment is required, and the flexible insulation section 3 can be directly fitted and overlapped with the core body. Finally, a metal plating layer 7 with a thickness of approximately 10 μm, made of indium, is deposited on the entire exterior of the heat pipe body using a magnetron sputtering process to enhance the airtightness of the heat pipe shell.

[0049] The method for preparing the flexible heat pipe described in this embodiment is as follows:

[0050] S1: Two square-section copper tubes with a side length of 3mm and a length of 50mm are provided as evaporation section 1 and condensation section 2, respectively. Three layers of 250-mesh copper wire mesh are filled into the two copper tubes. The copper wire mesh is sintered and connected to evaporation section 1, condensation section 2 and copper braided tape respectively by high-temperature sintering process to form a core. The copper wire mesh and copper braided tape are attached to the inner wall of the copper tube by sintering to form copper wire mesh sintered liquid absorption core 41 and copper braided tape liquid absorption core 42.

[0051] S2: The above core is fitted into the PU tube, and the two ends of the PU tube are respectively connected to one end of the evaporation section 1 and one end of the condensation section 1. The copper braided strip liquid-absorbing core 42 is inserted into the PU tube.

[0052] S3: The joint between the flexible insulation section 3 and the evaporation section 1 and the condensation section 2 is reinforced with Agilent Torr Seal high vacuum sealant to form joint 5;

[0053] S4: The port of condensation section 2 is shortened and sealed by inert gas shielded welding. Then, the heat pipe is evacuated and injected with liquid through the port of evaporation section 1. In this embodiment, liquid ammonia is used as the working fluid, and the injection volume is about 1.5 ml, accounting for 60% of the volume of the liquid absorber cavity. The vacuum degree is evacuated to 1 Pa or below. Then, the port of evaporation section 1 is sealed by cold welding and then reinforced by argon arc welding.

[0054] S5: Indium metal is deposited using magnetron sputtering to form a metal coating with a thickness of approximately 10 μm.

[0055] Example 3:

[0056] Figure 4 This is a schematic diagram of the flexible heat pipe described in this embodiment. In this embodiment, the evaporation section and condensation section are copper tubes with square cross-sections, and the flexible insulation section 3 is a copper corrugated pipe, the cross-section of which can be square or circular; the first liquid absorbent core 41 and the second liquid absorbent core are both sintered liquid absorbent cores with 3 layers of 300-mesh copper wire mesh.

[0057] The fabrication method of this flexible heat pipe is as follows:

[0058] S1: The flexible insulation section 3 is a copper corrugated pipe with a circular or square cross-section. When the cross-section of the copper corrugated pipe is circular, the evaporation section 1 and the condensation section 2 need to be rounded as described in the first embodiment of the present invention before proceeding to step S2. When the cross-section of the copper corrugated pipe is square, step S2 is performed directly.

[0059] S2: Connect three layers of 300-mesh copper wire mesh to one end of the evaporation section 1, and use a high-temperature sintering process to sinter and adhere it to the inner wall of the evaporation section to form a copper wire mesh sintered liquid absorption core. Then, put the liquid absorption core 4 into the interior of the flexible insulation section 3 and one end of the condensation section 2 respectively.

[0060] S3: The interfaces of the evaporation section 1, the condensation section 2 and the flexible insulation section 3 are sealed by brazing to form a sealed joint 5.

[0061] S4: The port of condensing section 2 is shortened and sealed by inert gas shielded welding. Then, the heat pipe is evacuated and injected with liquid through the port of evaporating section 1. In this embodiment, ethanol is used as the working medium and the amount of liquid injected is about 1.5 ml, accounting for 60% of the volume of the liquid absorber cavity. The vacuum degree is evacuated to 1 Pa or below. Then, the port of evaporating section 1 is sealed by cold welding and then sealed and reinforced by argon arc welding.

[0062] S5: A silver-indium alloy is deposited using an electroplating process to form a metal coating with a thickness of approximately 10 μm.

[0063] Example 4:

[0064] In this embodiment, the evaporation section 1 and the condensation section 2 are aluminum tubes, and the flexible insulation section 3 is an aluminum corrugated tube with a circular cross section; the first liquid suction core 41 and the second liquid suction core 42 are both sintered liquid suction types with 3 layers of 400-mesh copper wire mesh.

[0065] In this embodiment, the cross-sections of the evaporation section 1 and the condensation section 2 are triangular, trapezoidal, or semi-circular, and their shapes can be selected according to the internal space of the electronic device. First, one end of the evaporation section 1 and one end of the condensation section 2 are rounded as described in Embodiment 1. Three layers of 400-mesh copper wire mesh are sintered and connected to the rounded end of the evaporation section 1 using a high-temperature sintering process. Then, the copper wire mesh sintered liquid-absorbing core is fitted inside the flexible insulation section 3 and the rounded end of the condensation section 2. Next, the interface between the evaporation section 1, the condensation section 2, and the flexible insulation section 3 is sealed using a brazing process to form a sealing joint 5. Then, the other end of the condensation section 2 is welded and sealed. After completing the vacuuming and liquid injection process, the other end of the evaporation section 1 is sealed using argon arc welding. Finally, aluminum alloy is deposited by chemical plating to form a dense metal coating.

[0066] Example 5:

[0067] In this embodiment, the evaporation section 1 and the condensation section 2 are titanium tubes, and the flexible insulation section 3 is a titanium corrugated tube; the first liquid absorption core 41 is a sintered liquid absorption core with 3 layers of 200-400 mesh copper wire mesh, and the second liquid absorption core 42 is a copper braided strip liquid absorption core.

[0068] In this embodiment, the cross-sections of the evaporation section 1, the condensation section 2, and the flexible insulation section are all flat, which can further increase the contact area between the heat pipe and the external heat source, and meet the heat dissipation requirements of flat electronic devices. Several stainless steel core rods are inserted into the flat evaporation section 1 and condensation section 2, evenly distributed along their long sides. Copper powder and copper braided tape of 200-400 mesh are filled into the gaps between the core rods and the evaporation and condensation sections 1 and 2. The copper powder and copper braided tape are then sintered to adhere to the inner wall of the copper tube to form a core, creating a copper powder liquid-absorbing core 41 and a copper braided tape liquid-absorbing core 42. Next, the core is fitted into the flat flexible insulation section 3. The overlap between the flexible insulation section 3 and the evaporation and condensation sections 1 and 2 is then sealed and reinforced with adhesive to form a joint 5. One end of the condensation section is welded and sealed, a vacuum is drawn, liquid is injected, and the other end of the evaporation section 1 is sealed with argon arc welding. Finally, a gold-silver alloy plating is deposited on the heat pipe body by magnetron sputtering to improve the heat pipe's thermal conductivity and density.

[0069] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method of producing a flexible heat pipe, characterized by, Comprising the following steps: S1: providing an evaporation section, a condensation section and a flexible heat insulation section, wherein the evaporation section and the condensation section are made of metal, the flexible heat insulation section is a metal bellows or a polymer flexible tube, the side walls of the evaporation section and the condensation section are respectively provided with a plane for abutting against the outside, and the cross section of the flexible heat insulation section is circular or square; S2: when the cross section of the flexible heat insulation section is square and the cross sections of the evaporation section and the condensation section are also square, step S4 is performed; S3: when the cross section of the flexible heat insulation section is circular, the ends of the evaporation section and the condensation section are respectively subjected to rounding treatment, and then step S4 is performed; S4: combining wicks with the ends of the evaporation section and the condensation section to form a core body; wherein the wicks comprise first wicks and second wicks; the first wicks are located inside the evaporation section and the condensation section and are made of a capillary structure sintered from powder, porous wire mesh or woven belt; the second wicks are located inside the flexible heat insulation section and are made of porous wire mesh or woven belt or a composite structure of porous wire mesh and woven belt; S5: sleeving the core body in the flexible heat insulation section, overlapping and sealing one end of the flexible heat insulation section with one end of the evaporation section, and overlapping and sealing the other end of the flexible heat insulation section with one end of the condensation section to form a heat pipe body; S6: sealing one end of the heat pipe body, and then completing the processes of vacuumizing and liquid injection through the other end of the heat pipe body, and then sealing the other end of the heat pipe body.

2. The method of claim 1, wherein the flexible heat pipe is prepared by the steps of: After the other end of the heat pipe body is sealed, the following steps are further included: At least one of the following processes is used to deposit a metal layer on the outside of the heat pipe body: Magnetron sputtering, electroplating, chemical plating.

3. The preparation method of the flexible heat pipe according to claim 1, characterized in that: At least one of the following hydrophilic materials is used as the material of the first wicks and the second wicks: Copper, stainless steel, aluminum, titanium, nylon, carbon fiber, graphene, polypropylene.

4. The method of claim 1, wherein: The inner diameter of the flexible heat insulation section is greater than the outer diameters of the evaporation section and the condensation section, and the fitting tolerance is 0.1-0.5 mm.

5. The method of claim 1, wherein: The sealing of the flexible heat insulation section with the evaporation section and the condensation section is realized through a glue bonding process or a low-temperature welding process.

6. The preparation method of the flexible heat pipe according to claim 1, characterized in that: The wicks are combined with the evaporation section and the condensation section through high-temperature sintering or mechanical pressing.

7. The preparation method of the flexible heat pipe according to claim 1, characterized in that: When the flexible heat insulation section is a polymer flexible tube, a spring is embedded in the inside of the flexible heat insulation section.

8. The preparation method of the flexible heat pipe according to claim 1, characterized in that: The cross sections of the evaporation section and the condensation section are square, triangular or flat.

9. A flexible heat pipe, characterized in that: The flexible heat pipe comprises a pipe body with two closed ends and a working medium located in the pipe body; the pipe body comprises an evaporation section, a condensation section, a wick and a flexible heat insulation section, the flexible heat insulation section is overlapped with one end of the evaporation section and one end of the condensation section respectively, the other end of the evaporation section and the other end of the condensation section are sealed to form a closed heat pipe body; the side wall of the evaporation section and the side wall of the condensation section are respectively provided with a plane for abutting against the outside, the cross section of the flexible heat insulation section is circular or square; wherein the wick comprises a first wick and a second wick; the first wick is located inside the evaporation section and the condensation section and is made of a capillary structure sintered by powder, porous wire mesh or woven belt; the second wick is located inside the flexible heat insulation section and is made of porous wire mesh or woven belt or a composite structure of porous wire mesh and woven belt.

10. The flexible heat pipe according to claim 9, wherein: the evaporation section and the condensation section are square or triangular in cross section, the flexible heat insulation section is circular in cross section, and the end of the evaporation section and the condensation section overlapped with the flexible heat insulation section is rounded; or the evaporation section and the condensation section are square or flat in cross section, and the flexible heat insulation section is square or flat in cross section correspondingly. ​ ​

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