Flexible thermal diode and processing method thereof

Abstract

The invention provides a flexible thermal diode and a processing method thereof, and the flexible thermal diode comprises a flexible supporting structure which is provided with a plurality of parallel air channels of hollow structures in the length direction of the flexible supporting structure; the two or more directional flow liquid absorption cores are made of flexible materials and are stacked at the upper end and the lower end of the flexible supporting mechanism respectively, a gradually-dense rectangular hydrophobic structure is formed in the length direction of each directional flow liquid absorption core, and a liquid working medium is injected into each directional flow liquid absorption core; the flexible shell is made of flexible materials and wraps the flexible supporting structure and the directional flowing liquid absorption core in a hot pressing mode. According to the implementation mode, directional flowing of the liquid working medium can be controlled through the directional flowing wick, and therefore directional heat transfer is achieved. The directional flow liquid absorption core, the flexible supporting structure and the flexible shell can be greatly bent, and the flexibility of the flexible thermal diode can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal diodes, and in particular to a flexible thermal diode and a processing method thereof. Background Art

[0002] A thermal diode is a device that allows heat to flow in one direction but restricts or prevents flow in the opposite direction, similar to the property of an electrical diode that conducts electricity.

[0003] When the thermal diode operates in the forward direction, the working fluid evaporates and vaporizes in the evaporation section. Accelerating pressure differentials and gravity flow toward the condensation section, where it condenses into liquid and releases latent heat. Heat is transferred from the evaporation section to the condensation section through the flow of steam. Capillary forces and gravity return the condensed liquid to the evaporation section, completing a closed loop. Evaporation and condensation then continue, thus transferring heat from the evaporation section to the condensation section and circulating the working fluid within the tube.

[0004] When the thermal diode works in reverse, the heating end and the condensing end are swapped. By designing different airway structures or different liquid wick structures, the flow of gaseous working fluid or the reflux of liquid working fluid is hindered, so that the working fluid cannot complete a complete phase change cycle, thereby preventing heat from being effectively transferred.

[0005] However, traditional thermal diodes mostly use rigid packaging structures (such as plastic tubes or metal shells), which are difficult to adapt to the needs of flexible electronics, foldable devices or body-conforming thermal control systems. Summary of the Invention

[0006] The content of this disclosure is intended to briefly introduce concepts that will be described in detail in the detailed description below. The content of this disclosure is not intended to identify key features or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0007] Some embodiments of the present invention provide flexible thermal diodes and processing methods thereof to solve the technical problems mentioned in the above background technology section.

[0008] In a first aspect, some embodiments of the present invention provide a flexible thermal diode, comprising: A flexible support structure is provided with a plurality of parallel hollow air passages along its length; Two or more directional flow wicks are made of flexible material and are stacked on the upper and lower ends of the flexible support structure. Each directional flow wick has a gradually denser rectangular hydrophobic structure along its length and is filled with liquid. The flexible shell is made of flexible material and is hot-pressed to wrap the flexible support structure and the directional flow absorbent core.

[0009] In a second aspect, some embodiments of the present invention provide a method for processing the flexible thermal diode, comprising: The prepared directional flow wick is stacked on the upper and lower ends of the flexible support structure; Wrapping the flexible support structure and the directional flow wick with a flexible shell by heat pressing; Perform degassing and liquid working fluid injection operations; Perform secondary sealing and cutting treatment.

[0010] The above embodiments of the present invention have the following beneficial effects: The gradually denser rectangular hydrophobic structures of the directional flow wick control the directional flow of the liquid working medium, thereby achieving directional heat transfer. The directional flow wick, flexible support structure, and flexible shell are made of flexible materials, which can achieve large bending and ensure the flexibility of the flexible thermal diode.

[0011] The present invention can be applied to flexible or foldable electronic devices without causing a decrease in heat transfer performance due to bending. Therefore, the flexible thermal diode not only inherits the unidirectional heat control advantage of traditional thermal diodes, but also breaks through the physical limitations of rigid devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 is an exploded schematic diagram of an embodiment of a flexible thermal diode of the present invention; Figure 2 An exploded schematic diagram of an embodiment of a directional flow wick and a flexible support structure of the present invention; Figure 3 is a cross-sectional view of an embodiment of a directional flow wick and a flexible support structure of the present invention; Figure 4 is a structural schematic diagram of an embodiment of the flexible support structure of the present invention; Figure 5 A flow chart of an embodiment of a method for processing a flexible thermal diode of the present invention; Figure 6 An exploded schematic diagram of an embodiment of a flexible thermal diode of the present invention in a processing state; Figure 7Schematic diagram of an exploded view of an embodiment of the liquid-filled tube of the present invention.

[0014] Description of reference numerals: 1. Liquid-filled tube; 11. Needle; 12. Brass tube; 13. Heat shrink tubing; 2. Vacuum tube; 3. Flexible shell; 4. Directional flow wick; 5. Flexible support structure; 6. Airway; 7: Segmented structure. DETAILED DESCRIPTION

[0015] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0016] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0017] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0018] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0019] See also Figures 1 to 4 , Figure 1 is an exploded schematic diagram of an embodiment of a flexible thermal diode of the present invention; Figure 2An exploded schematic diagram of an embodiment of a directional flow wick and a flexible support structure of the present invention; Figure 3 is a cross-sectional view of an embodiment of a directional flow wick and a flexible support structure of the present invention; Figure 4 FIG. 1 is a schematic structural diagram of an embodiment of the flexible support structure of the present invention. Figures 1 to 4 As shown, the flexible thermal diode includes a flexible support structure 5 , three directional flow wicks 4 and a flexible shell 3 .

[0020] The flexible support structure 5 can be fabricated using 3D printing using a flexible material. Multiple parallel hollow air channels 6 are formed along the length of the flexible support structure 5. These air channels 6 can have a rectangular cross-section. The flexible material can be polycarbonate, which can bend significantly while also supporting the air channels. Of course, those skilled in the art may also select other flexible materials based on common knowledge.

[0021] The gas channel 6 is used for the flow of the working medium. To improve the flexibility of the flexible support structure 5, multiple rows and columns of segmented structures 7 can be provided on one side of the flexible support structure 5. This creates gaps between adjacent segmented structures 7, facilitating bending of the flexible support structure 5. When bent to a certain degree, two adjacent segmented structures 7 squeeze against each other, providing a resilient force for the flexible support structure 5 to return to its original shape.

[0022] The three directional flow wicks 4 are stacked on the upper and lower ends of the flexible support structure 5. The size of each directional flow wick 4 can be the same as that of the flexible support structure 5. Each directional flow wick 4 can include a hydrophilic copper mesh with a rectangular hydrophobic structure provided on the hydrophilic copper mesh. The rectangular hydrophobic structure is arranged along the length of the directional flow wick 4 from left to right ( Figure 1 The rectangular hydrophobic structure can be a molten particle of PET film deposited and melted onto the hydrophilic copper mesh.

[0023] Although the accompanying drawings illustrate an example in which one directional flow absorbent core 4 is stacked on the upper end of the flexible support structure 5 and two directional flow absorbent cores 4 are stacked on the lower end, this is not the only example. Those skilled in the art can make adjustments based on actual conditions. The upper and lower ends of the flexible support structure 5 can both be stacked with one or more directional flow absorbent cores 4.

[0024] Each directional flow wick 4 is filled with a liquid medium, which can be deionized water. In the forward mode of the flexible thermal diode, the liquid medium is heated and vaporized from the left end to the right end, condensed into liquid, and finally flows back to the left end by capillary force.

[0025] In the reverse mode, the liquid working medium is heated and vaporized from the right end to the left end, and then liquefied into liquid when cooled. Since the rectangular hydrophobic structure on the right end is relatively dense, the liquid encounters increasing resistance when flowing back to the right end, making it difficult for the liquid working medium to flow back.

[0026] The flexible shell 3 can be made of a flexible material and is cylindrical. After the stacked directional flow wicks 4 and the flexible support structure 5 are placed in the flexible shell 3, they are subjected to heat pressing treatment by a heat machine, so that the flexible shell 3 can tightly wrap the directional flow wicks 4 and the flexible support structure 5. At the same time, the two ends of the flexible shell 3 can be sealed, thereby forming the flexible thermal diode of the present invention.

[0027] As an example, the flexible material may be an aluminum-plastic composite film, which specifically includes a nylon outer layer, an aluminum foil and a polypropylene inner layer from the outside to the inside, wherein the polypropylene inner layer is hot-pressed with the directional flow absorbent core 4 .

[0028] This flexible thermal diode not only controls the directional flow of fluid through the directional flow wick 4, thereby achieving directional heat transfer, but also the directional flow wick 4, flexible support structure 5, and flexible housing 3 are made of flexible materials, all of which can bend significantly, ensuring the flexibility of the flexible thermal diode.

[0029] The present invention can be applied to flexible or foldable electronic devices without the degradation of heat transfer performance caused by bending. Therefore, this flexible thermal diode not only inherits the unidirectional heat control advantages of traditional thermal diodes, but also breaks through the physical limitations of rigid devices, opening up new directions for the next generation of intelligent thermal diode technology.

[0030] The present application also provides a method for processing a flexible thermal diode, which can be used for the flexible thermal diodes in the above embodiments. Figure 5 FIG. 5 shows a process 500 of an embodiment of a method for processing a flexible thermal diode provided by the present application. The method may include the following steps: Step 501: stack the prepared directional flow wick on the upper and lower ends of the flexible support structure.

[0031] In some embodiments, a plurality of directional flow wicks and a flexible support structure are prepared and stacked on top and bottom of the flexible support structure. The directional flow wicks can be the same size as the flexible support structure so that, when stacked, they are aligned with the flexible support structure.

[0032] In some embodiments, in an optional implementation, when preparing a directional flow wick, a copper mesh is first cut to a corresponding size and then chemically modified to obtain a hydrophilic copper mesh. Next, a PET film is covered on the hydrophilic copper mesh. Finally, a laser process is used to deposit and melt the PET film onto the hydrophilic copper mesh to obtain a rectangular hydrophobic structure. The rectangular hydrophobic structure extends from left to right along the length of the directional flow wick ( Figure 1 The directional flow wick is gradually denser (in the direction of the flow).

[0033] Each directional flow wick is filled with liquid. In the flexible thermal diode's forward mode, the liquid vaporizes from the left end to the right end, condenses into a liquid, and finally flows back to the left end due to capillary forces. In the reverse mode, the liquid vaporizes from the right end to the left end, then condenses into a liquid when cooled. Due to the dense rectangular hydrophobic structures on the right end, the liquid encounters increasing resistance to return to the right end, making it difficult for the liquid to flow back.

[0034] The flexible support structure can be made of polycarbonate through 3D printing. It can be bent to a large extent and can support the airway.

[0035] Step 502: wrap the flexible support structure and the directional flow wick with the flexible shell by heat pressing.

[0036] In some embodiments, the flexible housing can be made of an aluminum-plastic composite film, specifically comprising a nylon outer layer, an aluminum foil, and a polypropylene inner layer. During processing, the cylindrical flexible housing is sleeved onto the stacked directional flow wick and the flexible support structure.

[0037] The length of the flexible shell may be greater than the length of the flexible support structure, so that there are reserved gaps between the two ends of the flexible shell and the flexible support structure and the directional flow absorbent core.

[0038] See also Figure 6 , Figure 6 FIG. 1 is an exploded schematic diagram of an embodiment of the flexible thermal diode of the present invention in a processing state. Figure 6 As shown, the vacuum tube 2 and the liquid filling tube 1 are respectively extended into the reserved gaps at both ends, wherein the vacuum tube 2 is close to the dense end of the rectangular hydrophobic structure, and the liquid filling tube 1 is close to the sparse end of the rectangular hydrophobic structure.

[0039] Finally, the flexible housing 3 is heat-pressed using a heat press, bonding the polypropylene inner layer to the directional flow wick 4 and sealing the needles of the vacuum tube 2 and the filling tube 1 into the reserved gap. Furthermore, epoxy resin can be applied to the joints between the vacuum tube, the filling tube, and the flexible housing 3 to achieve a seal.

[0040] In some optional implementations of the embodiments, the structures of the vacuum tube and the liquid filling tube are the same, and the preparation of the liquid filling tube is used as an example for description. Figure 7 , Figure 7 FIG. 1 is an exploded schematic diagram of an embodiment of the liquid-filled tube of the present invention. Figure 7 As shown, first, cut the heat shrink tube 13 and the brass tube 12. Next, put the two ends of the heat shrink tube 13 onto the brass tube 12 and the needle 11. Finally, use a hot air gun to heat shrink the heat shrink tube 13 to complete the preparation of the liquid-filled tube 1.

[0041] Step 503: Degassing and injection of liquid working medium are performed.

[0042] In some embodiments, a certain amount of liquid working medium is first injected into the liquid filling tube, and the gas in the liquid filling tube is discharged to ensure that the liquid filling tube is entirely filled with liquid working medium, and then the liquid filling tube is clamped with a strong water stop clamp.

[0043] Next, connect the vacuum tube to the vacuum equipment, perform a vacuum operation, and complete the degassing. After completion, use a strong water-stop clamp to clamp the vacuum tube.

[0044] Then, the strong water-stop clamp of the liquid filling pipe is opened, and under the action of negative pressure, the liquid working medium in the liquid filling pipe is automatically sucked in. When the amount of liquid working medium sucked in reaches a preset threshold, the strong water-stop clamp is used to clamp the liquid filling pipe. It should be noted that the amount of liquid working medium sucked in can be determined by repeated experiments by those skilled in the art.

[0045] Next, the flexible thermal diode is placed on a heating platform and heated for a preset time to release the non-condensable gases in the liquid working fluid. After heating is complete, the vacuum hose is connected to the vacuum equipment, and the strong water-stop clamp on the vacuum hose is opened to extract the non-condensable gases, completing the secondary degassing.

[0046] Finally, use a strong water stop clamp to clamp the vacuum hose.

[0047] Step 504: perform secondary sealing and cutting processing.

[0048] In some embodiments, the secondary sealing and cutting process is similar to the secondary degassing process of related heat pipes. The flexible housing is resealed at the preset gap using a sealing device, and finally, the sealed flexible housing is cut off using a cutting device. The cut position avoids the needle, completing the secondary sealing and cutting process of the reserved gaps at both ends. This allows the vacuum tube and the liquid filling tube to be separated from the flexible housing, and also seals both ends of the cut flexible housing, completing the processing of the flexible thermal diode. Finally, the processed flexible thermal diode needs to be subjected to heat transfer testing, etc. to ensure normal operation.

[0049] The above technical solution, a key feature of an embodiment of the present invention, addresses the issues of degassing and liquid injection during the manufacturing process of flexible thermal diodes. This invention heat-presses the vacuum tube and liquid filling tube into the reserved gaps at both ends of the flexible housing, sealing the needle within the reserved gaps. This prevents leakage of gas or liquid, improving sealing and reliability.

[0050] Through the secondary sealing and cutting process, the two ends of the flexible shell can be sealed while preventing external air from entering during the removal of the vacuum tube and the liquid filling tube, thereby improving the reliability of the flexible thermal diode processing.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible thermal diode, characterized in that: include: A flexible support structure is provided with a plurality of parallel hollow air passages along its length; Two or more directional flow wicks are made of flexible material and are stacked on the upper and lower ends of the flexible support structure. Each directional flow wick has a gradually denser rectangular hydrophobic structure along its length and is filled with liquid. The flexible shell is made of flexible material and is hot-pressed to wrap the flexible support structure and the directional flow absorbent core.

2. The flexible thermal diode according to claim 1, characterized in that The directional flow wick comprises a hydrophilic copper mesh on which the rectangular hydrophobic structure is arranged.

3. The flexible thermal diode according to claim 2, characterized in that The rectangular hydrophobic structure is a PET film deposited and melted onto molten particles on a hydrophilic copper mesh.

4. The flexible thermal diode according to claim 1, characterized in that The flexible supporting structure is made of polycarbonate.

5. The flexible thermal diode according to claim 1, characterized in that The flexible shell is made of aluminum-plastic composite film.

6. A method for processing a flexible thermal diode as claimed in any one of claims 1 to 5, characterized in that: The method comprises: The prepared directional flow wick is stacked on the upper and lower ends of the flexible support structure; Wrapping the flexible support structure and the directional flow wick with a flexible shell by heat pressing; Perform degassing and liquid working fluid injection operations; Perform secondary sealing and cutting treatment.

7. The method for processing a flexible thermal diode according to claim 6, characterized in that: The preparation of the directional flow wick comprises the following steps: Cutting the copper mesh and preparing the copper mesh into a hydrophilic copper mesh; The hydrophilic copper mesh is covered with a PET film, and the PET film is deposited and melted onto the hydrophilic copper mesh by laser processing to obtain a rectangular hydrophobic structure, wherein the rectangular hydrophobic structure gradually becomes denser along the length direction of the hydrophilic copper mesh.

8. The method for processing a flexible thermal diode according to claim 7, characterized in that: The method of wrapping the flexible support structure and the directional flow absorbent core with the flexible shell by heat pressing comprises: Wrapping the stacked flexible support structure and the directional flow wick with a flexible shell, wherein the flexible shell is longer than the flexible support structure and the directional flow wick, and a reserved gap is formed at both ends of the flexible shell; Insert the vacuum tube and the liquid filling tube into the reserved gaps at both ends respectively, wherein the vacuum tube is close to the dense end of the molten particles, and the liquid filling tube is close to the sparse end of the molten particles; The flexible shell is heat-pressed by a heat press.

9. The method for processing a flexible thermal diode according to claim 8, characterized in that: The degassing and liquid working medium injection operations include: After vacuuming through the vacuum tube, close the vacuum tube to complete the degassing; Open the liquid filling pipe, inject the liquid working medium under the action of negative pressure, and then close the liquid filling pipe; Place it on a heating platform and heat it for a preset time to release the non-condensable gas in the liquid working medium; After secondary degassing through the vacuum tube, the vacuum tube is sealed.

10. The method for processing a flexible thermal diode according to claim 9, characterized in that: The preparation of the vacuum tube and the liquid-filled tube includes the following steps: Connect the two ends of the heat shrink tube to the brass tube and the needle respectively; The heat shrinkable tube is heated to heat-shrink the vacuum tube and the liquid-filled tube.

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