Flexible graphite cold chain with high thermal conductivity

Abstract

The invention relates to a flexible high-thermal-conductivity graphite cold chain which comprises a graphene film laminated body and two metal terminals arranged at the two ends of the graphene film laminated body, and the part, fixed by the metal terminals, of the graphene film laminated body is a rigid section of the graphene film laminated body. The part, which is positioned between the two metal terminals and is not fixed, of the graphene film laminated body is a flexible section of the graphene film laminated body; and the flexible section of the graphene film laminated body is wrapped with a polyimide film. A glue filling groove is formed in the metal terminal; and heat-conducting glue is filled between the metal terminal and the rigid section of the graphene film laminated body. According to the invention, the high-thermal-conductivity graphene film and the metal terminal are compounded by filling the assembly gap with the heat-conducting glue, so that the contact thermal resistance of the edge of the laminated graphite film and the metal terminal is greatly reduced, and the heat transfer path in the thickness direction of the graphite cold chain is improved, thereby achieving the effect of improving the heat-conducting property of the graphite cold chain.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible and efficient heat conduction, and relates to a flexible high - thermal - conductivity graphite cold chain. Background Art

[0002] At present, flexible graphite cold chains have been widely used in spacecraft such as satellites, and are commonly used for flexible connections between cryogenic cold optical components, detectors, etc. and the cold heads of mechanical refrigerators or other cold sources. It can not only avoid the influence of low - temperature deformation on optical components or detectors under rigid connection conditions, but also meet the on - orbit moving and focusing requirements of optical components, detectors, etc., and at the same time reduce the interference of mechanical vibration of the refrigerator on the response signal of the detector. However, in recent years, the requirements for on - satellite optical imaging quality have been gradually increasing, and it has been gradually developing towards the directions of low temperature, low deformation, low weight, and high heat dissipation. The requirements for the heat conduction ability of graphite cold chains have also been gradually increasing.

[0003] Traditional crimped graphite cold chains are made by stacking graphene films layer by layer, and the ends of the cold chain are fixed by crimping with metal terminals. There are disadvantages such as the inability of the side edges of graphene films to contact and conduct heat with metal terminals. When heat is applied to one end of the flexible graphite cold chain, while the heat is conducted from the hot end of the graphene film to the cold end, it needs to be conducted layer by layer in the thickness direction of the graphene film. However, the current thermal conductivity of the graphene film in the thickness direction is only 3 - 10 W / (m·K), and there is a large amount of contact thermal resistance between layers, resulting in poor heat conduction performance of the flexible graphite cold chain in the thickness direction. Increasing the number of graphene film layers has a very limited improvement in the heat conduction performance of the cold chain and poor economic benefits. Therefore, a welding process for graphene films and metal terminals has emerged. After welding the graphene film and the metal terminal into a whole through a filler metal, the heat can be conducted in the thickness direction by the metal terminal and the filler metal with higher thermal conductivity, and then conducted from the filler metal to each layer of graphene film, which can significantly improve the heat conduction performance of the graphite cold chain. However, brazing needs to be carried out in a vacuum and a high - temperature furnace, and factors such as the filler metal system, filler metal overflow, and high - temperature deformation need to be considered. The overall process is complex, difficult, and has a long production cycle. Summary of the Invention

[0004] The object of the present invention is to provide a flexible high - thermal - conductivity graphite cold chain. Aiming at the problems such as poor heat transfer effect caused by the inability of the metal terminals of traditional graphite cold chains to contact the edges of graphene films, and the complex and difficult brazing process of graphite cold chains, a method of filling the assembly gap with a thermal conductive adhesive is used to compound the high - thermal - conductivity graphene film and the metal terminal, which greatly reduces the contact thermal resistance between the edges of the laminated graphite film and the metal terminal, improves the heat transfer path in the thickness direction of the graphite cold chain, and thus achieves the effect of improving the heat conduction performance of the graphite cold chain.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A flexible high - thermal - conductivity graphite cold chain includes a graphene film laminate and two metal terminals arranged at both ends thereof. The metal terminals include a metal base plate, a metal cover plate, and cover plate screws. Both ends of the graphene film laminate are arranged between the metal base plate and the metal cover plate and are fixed by the cover plate screws. The part of the graphene film laminate fixed by the metal terminals is the rigid section of the graphene film laminate, and the part of the graphene film laminate located between the two metal terminals and not fixed is the flexible section of the graphene film laminate.

[0007] The metal base plate is a semi - enclosed structure with one - side opening formed by a base - plate frame, and a glue - filling groove is arranged inside the base - plate frame. The rigid section of the graphene film laminate is arranged in the space surrounded by the glue - filling groove. The metal cover plate is provided with glue - filling holes corresponding to the glue - filling groove. The glue - filling groove is filled with thermal - conductive glue. The flexible section of the graphene film laminate wraps a polyimide film.

[0008] The graphene film laminate is stacked by 10 - 200 layers of high - thermal - conductivity pyrolytic graphene films. The single - layer thickness of the graphene film is 25 - 80μm, and the thermal conductivity is ≥1000W / (m·K). The metal base plate and the metal cover plate are made of high - thermal - conductivity metal materials.

[0009] A column is arranged at the center of the metal base plate. The rigid section of the graphene film laminate is provided with positioning holes corresponding to the column, and the rigid section of the graphene film laminate is arranged in the space surrounded by the column and the glue - filling groove.

[0010] The metal base plate is further provided with a boss. The rigid section of the graphene film laminate is provided with through - holes corresponding to the boss. The rigid section of the graphene film laminate is arranged in the space formed by the column, the boss, and the glue - filling groove.

[0011] A gap is left between the rigid section of the graphene film laminate and the boss, and this gap forms a glue - filling groove at the edge of the boss. The metal cover plate is provided with glue - filling holes corresponding to the glue - filling groove at the edge of the boss, and the glue - filling groove at the edge of the boss is filled with thermal - conductive glue.

[0012] At least two bosses are provided, and the bosses are symmetrically arranged with the column as the center.

[0013] The boss is provided with mounting holes, and a non - loosening screw is arranged in at least one of the mounting holes.

[0014] The non - loosening screw is an M4 non - loosening screw.

[0015] The thermal - conductive glue is a high - thermal - conductivity AB silicone rubber, and the thermal conductivity is ≥1.0W / (m·K).

[0016] The cover plate screw is an M3 cover plate screw.

[0017] The advantages of the present invention are as follows: 1. Innovatively using thermal conductive adhesive to fill the assembly gap, compounding the high thermal conductivity graphene film with the metal terminal, significantly reducing the contact thermal resistance between the edge of the stacked graphite film and the metal terminal, improving the heat transfer path in the thickness direction of the graphite cold chain, thereby enhancing the thermal conductivity of the graphite cold chain; 2. The present invention uses thermal conductive adhesive to compound the graphene film laminate and the high thermal conductivity metal terminal, optimizing the heat conduction in the thickness direction of the graphene film laminate, which can be popularized and applied to the heat transfer scenario where the cold and hot ends are on different planes, enhancing the versatility of the graphite cold chain; 3. The setting of the boss on the bottom plate and the reserved gap in the contact area between the boss and the graphene film laminate as the glue filling groove enhances the heat conduction in the thickness direction of the graphene film laminate; 4. The flexible section of the graphene film laminate is coated with polyimide film to prevent the generation of redundant pollutants such as graphite chips; 5. The present invention has the characteristics of simple structure, light weight, easy processing, good thermal conductivity, convenient assembly, and anti-chip dropping, and can be used for the efficient thermal control of space cameras. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the present invention;

[0019] Figure 2 is a structural sectional view of the present invention;

[0020] Figure 3 is a schematic structural diagram of the metal bottom plate of the present invention;

[0021] Figure 4 is a schematic structural diagram of the metal cover plate of the present invention;

[0022] Figure 5 is a diagram showing the distribution of the thermal conductive adhesive of the present invention;

[0023] In the figure: 1 - graphene film laminate; 2 - metal bottom plate; 21 - bottom plate frame; 22 - boss; 23 - column; 24 - mounting hole; 25 - glue filling groove; 3 - metal cover plate; 31 - glue filling hole; 4 - cover plate screw; 5 - non-loosening screw; 6 - thermal conductive adhesive; 7 - polyimide film. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present invention will be further described below with reference to the accompanying drawings. The accompanying drawings are only for illustrative purposes and should not be construed as a limitation to this patent.

[0025] For the sake of more concise description of this embodiment, some components that are well-known to those skilled in the art but not relevant to the main content of this creation will be omitted in the drawings or description. In addition, for the convenience of expression, some components in the drawings will be omitted, enlarged or reduced, but this does not represent the size or all structures of the actual product.

[0026] The present invention discloses a flexible high thermal conductivity graphite cold chain, as Figure 1 ,Figure 2 As shown in the figure, it includes a graphene film laminate 1 and two metal terminals provided at both ends thereof. The metal terminals include a metal base plate 2, a metal cover plate 3, and a cover plate screw 4. Both ends of the graphene film laminate 1 are provided between the metal base plate 2 and the metal cover plate 3 and are fixed by the cover plate screw 4; the cover plate screw 4 is an M3 cover plate screw.

[0027] The part of the graphene film laminate 1 fixed by the metal terminals is the rigid section of the graphene film laminate 1, and the part of the graphene film laminate 1 located between the two metal terminals and not fixed is the flexible section of the graphene film laminate 1; the flexible section of the graphene film laminate 1 wraps the polyimide film 7.

[0028] As Figure 3 shown, the metal base plate 2 is a semi-enclosed structure with an opening on one side formed by a base plate frame 21. Preferably, the size is 80mm×92mm×11mm.

[0029] A glue filling groove 25 with a depth of 1.2 - 2mm is provided inside the base plate frame 21 for filling the thermal conductive glue 6; preferably, the glue filling groove 25 is set to 1.5mm, and the thermal conductive glue 6 is a high thermal conductivity AB silicone rubber with good fluidity, and the thermal conductivity ≥1.0W / (m·K).

[0030] Furthermore, the metal base plate 2 is also provided with a boss 22, and through holes corresponding to the boss 22 are provided in the rigid section of the graphene film laminate 1; the rigid section of the graphene film laminate 1 is arranged in the space formed by the upright post 23, the boss 22, and the glue filling groove 25.

[0031] A gap of 1.5mm is left between the rigid section of the graphene film laminate 1 and the boss 22, and this gap forms a glue filling groove at the edge of the boss 22; the metal cover plate 3 is provided with a glue filling hole 31 corresponding to the glue filling groove at the edge of the boss 22, and the glue filling groove at the edge of the boss 22 is filled with the thermal conductive glue 6.

[0032] The rigid section of the graphene film laminate 1 is arranged in the space surrounded by the glue filling groove 25; the metal cover plate 3 is provided with a glue filling hole 31 corresponding to the glue filling groove 25, and preferably the glue filling hole 31 is set to be 1.5mm wide.

[0033] The graphene film laminate 1 is stacked by 10 - 200 layers of high thermal conductivity pyrolytic graphene films. The single-layer thickness of the graphene film is 25 - 80μm. Preferably, the single-layer thickness is 75μm, and the size after stacking is 268mm×80mm×8mm. The thermal conductivity ≥1000W / (m·K); the metal base plate 2 and the metal cover plate 3 are made of high thermal conductivity metal materials, and the materials of the metal base plate 2 and the metal cover plate 3 are 2A12 aluminum alloy.

[0034] As Figure 3As shown, a column 23 with a size of 11mm×Φ3mm is provided at the center of the metal base plate 2 for positioning the graphene film laminate 1. The rigid section of the graphene film laminate 1 is provided with positioning holes corresponding to the column 23. To improve the bonding quality and reduce the chipping of the graphene film, the edge of the graphene film laminate 1 should be kept flat. Therefore, both the positioning holes and the edge cutting of the graphene film laminate 1 are processed by die cutting, and the processing accuracy is better than 0.05mm.

[0035] The rigid section of the graphene film laminate 1 is arranged in the space surrounded by the column 23 and the glue filling groove 25.

[0036] At least two bosses 22 are provided, generally four bosses 22 are provided, and the bosses 22 are symmetrically arranged with the center of the column 23.

[0037] The bosses 22 are provided with mounting holes 24, and at least one mounting hole 24 is provided with a non-loosening screw 5. The non-loosening screw 5 is an M4 non-loosening screw; when pre-installing the M4 non-loosening screw, it is preferred to use the M4 non-loosening screw to pre-fix both ends when installing the cold chain, so as to improve the convenience when the assembly space on the satellite is narrow.

[0038] During specific production, 1 piece of 25μm polyimide film 7 is used, which is cut and wrapped around the flexible section of the graphene film laminate 1, and the overlapping part of the polyimide film 7 is fixed with polyimide tape. Among them, the width of the polyimide film 7 is slightly longer than the length of the flexible section of the graphene film laminate 1; the length of the polyimide film 7 is slightly longer than the cross-sectional perimeter of the graphene film laminate 1. When wrapping, it should be ensured that the graphene film of the flexible section of the graphene film laminate 1 is in a fluffy state to avoid affecting the flexibility of the cold chain.

[0039] Fill the thermal conductive adhesive 6. Using a glue filling device, the thermal conductive adhesive 6 is filled into the glue filling groove 25 of the metal base plate 2 one by one through the glue filling holes 31 of the metal cover plate 3. To ensure the complete filling of the thermal conductive adhesive 6, it should be ensured that the outlet of the glue filling device is placed at the bottom of the glue filling groove 25 during filling, and when the current glue filling hole 31 is full and the thermal conductive adhesive 6 can be observed in the adjacent glue filling hole 31, fill the next glue filling hole 31; repeat the above operation until all the glue filling holes 31 are filled and a small amount overflows, then stop filling. Use a dust-free cloth to wipe off the small amount of overflowing thermal conductive adhesive 6. Let it stand at room temperature for more than 72 hours to cure the thermal conductive adhesive 6.

[0040] The above is only the preferred embodiment of the present invention, and is not used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the patent application scope of the present invention should fall within the technical scope of the present invention.

Claims

1. A flexible high thermal conductivity graphite cold chain, comprising a graphene film stack (1) and two metal terminals arranged at both ends thereof, the metal terminals comprising a metal base plate (2), a metal cover plate (3) and a cover plate screw (4), the two ends of the graphene film stack (1) being arranged between the metal base plate (2) and the metal cover plate (3) and being fixed by the cover plate screw (4); the portion of the graphene film stack (1) fixed by the metal terminals is a rigid section of the graphene film stack (1), and the portion of the graphene film stack (1) located between the two metal terminals and not fixed is a flexible section of the graphene film stack (1); Features: The metal bottom plate (2) is a semi-enclosed structure with one side open and formed by a bottom plate frame (21); a glue filling groove (25) is arranged on the inner side of the bottom plate frame (21); the rigid section of the graphene film stack (1) is arranged in the space surrounded by the glue filling groove (25); the metal cover plate (3) is provided with a glue filling hole (31) corresponding to the glue filling groove (25); the glue filling groove (25) is filled with thermal conductive glue (6); and the flexible section of the graphene film stack (1) is wrapped with a polyimide film (7).

2. The flexible high thermal conductivity graphite cold chain according to claim 1, characterized in that: The graphene film stack (1) is formed by stacking 10-200 layers of high thermal conductivity pyrolytic graphene films; the graphene film single layer thickness is 25-80 μm, and the thermal conductivity coefficient is ≥1000 W / (m·K); the metal bottom plate (2) and the metal cover plate (3) are made of high thermal conductivity metal materials.

3. The flexible high thermal conductivity graphite cold chain according to claim 2, characterized in that: A column (23) is arranged at the center of the metal bottom plate (2), a positioning hole corresponding to the column (23) is arranged at the rigid section of the graphene film stack (1), and the rigid section of the graphene film stack (1) is arranged in a space surrounded by the column (23) and the glue filling groove (25).

4. The flexible high thermal conductivity graphite cold chain according to claim 3, characterized in that: The metal base plate (2) is also provided with a boss (22), and the rigid section of the graphene film stack (1) is provided with a through hole corresponding to the boss (22); the rigid section of the graphene film stack (1) is arranged in a space formed by the column (23), the boss (22) and the glue filling groove (25).

5. The flexible high thermal conductivity graphite cold chain according to claim 4, characterized in that: A gap is left between the rigid section of the graphene film stack (1) and the boss (22), and the gap forms a glue filling groove at the edge of the boss (22); the metal cover plate (3) is provided with a glue filling hole (31) corresponding to the glue filling groove at the edge of the boss (22), and the glue filling groove at the edge of the boss (22) is filled with thermal conductive glue (6).

6. The flexible high thermal conductivity graphite cold chain according to claim 5, characterized in that: At least two bosses (22) are provided, and the bosses (22) are symmetrically arranged around the center of the column (23).

7. The flexible high thermal conductivity graphite cold chain according to claim 6, characterized in that: The boss (22) is provided with a mounting hole (24), and a captive screw (5) is arranged in at least one mounting hole (24).

8. The flexible high thermal conductivity graphite cold chain according to claim 7, characterized in that: The captive screw (5) is an M4 captive screw.

9. The flexible high thermal conductivity graphite cold chain according to claim 1, characterized in that: The thermal conductive adhesive (6) is AB silicone rubber with high thermal conductivity, and the thermal conductivity is ≥1.0 W / (m·K).

10. The flexible high thermal conductivity graphite cold chain according to claim 1, characterized in that: The cover screws (4) are M3 cover screws.

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