Large-area ultrathin vapor chamber, preparation method thereof and battery thermal management system

Abstract

A large-area ultrathin vapor chamber comprises a cover plate, a bottom plate, a liquid absorption core and a supporting structure, a cavity in a negative pressure state is formed between the cover plate and the bottom plate, and the cavity is filled with a phase change working medium; the liquid absorbing core and the supporting structure are both located in the cavity, the supporting structure adopts a plane silk screen and is used for supporting the cavity, and a steam channel used for steam flowing is formed in the supporting structure; the cavity comprises a heat source area and a heat dissipation condensation area, the phase change working medium evaporates in the heat source area and condenses in the heat dissipation condensation area, and the steam channel extends to the heat dissipation condensation area from the heat source area. The invention also relates to a preparation method of the large-area ultrathin vapor chamber and a battery thermal management system adopting the large-area ultrathin vapor chamber. The heat diffusivity of steam in the vapor chamber and the circulation efficiency of a vapor-liquid working medium can be improved, it is guaranteed that the ultra-thin vapor chamber has good heat transfer performance under the large heat dissipation area, and the ultra-thin vapor chamber belongs to the technical field of heat dissipation components.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation components, and in particular to a large-area ultra-thin vapor chamber and a preparation method thereof, and a battery thermal management system. Background Art

[0002] The rapid progress of new energy technologies has promoted the development of the energy storage industry. As the energy density of energy storage batteries increases, the safety risks caused by battery heat generation have also increased exponentially, especially under the development trend of highly integrated energy storage equipment. Ultra-thin heat spreaders rely on the flow of internal vapor-liquid working fluids and phase change heat to quickly respond to heat. They can transfer battery heat in a compact space and ensure good temperature uniformity on a two-dimensional plane, thereby ensuring the thermal safety of energy storage batteries.

[0003] The current ultra-thin heat spreader heat dissipation area is mostly suitable for small-sized electronic devices such as mobile phone CPUs. The sintered flat screen is used as the liquid absorption core to drive the reflux and phase change of the working fluid. The columns and grooves etched or stamped on the thin plate cavity are the support structure of the internal steam space. However, when the ultra-thin heat spreader is used for energy storage battery heat dissipation, the difficulty and cost of processing the internal support structure increase due to the expansion of the design area. Summary of the invention

[0004] In view of the technical problems existing in the prior art, one object of the present invention is to provide a large-area ultra-thin vapor chamber.

[0005] Another object of the present invention is to provide a method for preparing a large-area ultra-thin vapor chamber.

[0006] Another object of the present invention is to provide a battery thermal management system.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a large-area ultra-thin heat spreader, comprising a cover plate, a bottom plate, a liquid wick and a supporting structure, a cavity in a negative pressure state is formed between the cover plate and the bottom plate, and a phase change medium is filled in the cavity; the liquid wick and the supporting structure are both located in the cavity, the supporting structure adopts a flat wire mesh and is used to support the cavity, and a steam channel for steam flow is opened on the supporting structure; the cavity comprises a heat source area and a heat dissipation condensation area, the phase change medium evaporates in the heat source area and condenses in the heat dissipation condensation area, and the steam channel extends from the heat source area to the heat dissipation condensation area.

[0008] After adopting this structure, the heat spreader has higher processing efficiency and economy. The two ends of the steam channel start from the heat source area and the heat dissipation condensation area respectively, which is beneficial to enhance the phase change process of the working fluid and the circulation efficiency of the vapor-liquid working fluid, and improve the heat transfer performance of the ultra-thin heat spreader; the supporting structure is provided with a hollow steam channel. Such a reasonable and reliable internal design can ensure the mechanical bearing and the flow diffusion of the steam, so as to achieve the effect of efficient heat dissipation of large-area energy storage batteries.

[0009] As a preferred embodiment, the steam channel is in the shape of a rectangular strip and is formed by die cutting. One end of the steam channel is located in the heat source area, and the other end is located in the heat dissipation condensation area.

[0010] Preferably, the support structure is made of copper, aluminum or nickel, the mesh pore diameter of the support structure is greater than 500 μm, there are multiple steam channels, and the spacing between adjacent steam channels is greater than 3 times the sum of the mesh pore diameter and the wire diameter.

[0011] As a preferred embodiment, the support structure is treated with hydrophobicity, and the absorbent core is treated with hydrophilicity.

[0012] As a preferred embodiment, the liquid absorbent core adopts a flat screen, and the mesh pore diameter of the liquid absorbent core is less than 10 μm.

[0013] As a preferred embodiment, the wick and the support structure are both woven from copper wires, and the diameter of the copper wires used in the wick is smaller than the diameter of the copper wires used in the support structure.

[0014] As a preference, the liquid absorbent core and the support structure are stacked in the thickness direction, and the sum of the thickness of the liquid absorbent core and the support structure is equal to the thickness of the cavity.

[0015] As a preferred embodiment, the width of the steam channel gradually increases from the heat source area to the heat dissipation and condensation area.

[0016] A method for preparing a large-area ultra-thin vapor chamber comprises the following steps:

[0017] S1, the cover plate and the base plate are manufactured by stamping, etching or machining;

[0018] S2, using a die-cutting method to process the outer contours of the wick and the support structure, as well as the steam channel in the support structure;

[0019] S3, placing the liquid wick, the support structure and the bottom plate in a reducing atmosphere and connecting them by high-temperature sintering, and then connecting the part to the cover plate by a brazing process;

[0020] S4, injecting phase change medium into the cavity between the cover plate and the bottom plate, and performing degassing operation to ensure the vacuum degree of the inner cavity, and then performing sealing processing.

[0021] A battery thermal management system adopts the above-mentioned large-area ultra-thin heat spreader, including multiple energy storage batteries, and the heat source area of ​​the large-area ultra-thin heat spreader is in contact with the energy storage batteries; the large-area ultra-thin heat spreader is vertically placed between adjacent energy storage batteries, or horizontally placed at the bottom of the energy storage batteries.

[0022] In general, the present invention has the following advantages:

[0023] The internal liquid absorbent core and the supporting structure of the present invention are both made of a flat wire mesh, which has certain flexibility and controllable thickness, can adapt to processes such as extrusion and bending and maintain structural integrity, and the processing technology used is highly efficient and relatively low in cost.

[0024] The supporting structure of the present invention is a plane wire mesh with porous characteristics, and its woven structure can enhance the heat transfer in the thickness direction of the ultra-thin heat spreader.

[0025] The present invention designs and processes a strip-shaped hollow structure in the supporting plane screen to form a steam flow channel with low pressure drop, which is beneficial to the efficient diffusion of steam, thereby ensuring the temperature uniformity on the plane of the large-area ultra-thin heat spreader. At the same time, the shape of the flow channel is formed by punching, and the flow channel shape design also has strong flexibility.

[0026] The present invention is easy to install and requires no maintenance, is responsive to changes in heat input, can cope with the heat dissipation of energy storage batteries in different heat generation ranges, maintains the batteries under variable operating conditions within a suitable operating temperature range, and the temperature difference of the batteries is lower than the limit requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an exploded view of the large-area ultra-thin heat sink of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of the liquid-absorbing core and the supporting structure after sintering.

[0029] Figure 3 This is a schematic diagram of the structure after brazing of the base plate, wick and support structure.

[0030] Figure 4 This is a schematic diagram of the application of the ultra-thin heat spreader on both sides of the energy storage battery in the second embodiment.

[0031] Figure 5 This is a schematic diagram of the application of the ultra-thin heat spreader in Example 3 to dissipate heat from the energy storage battery on one side.

[0032] Among them, 1 is the bottom plate, 2 is the liquid absorption core, 3 is the supporting structure, 4 is the steam channel, 5 is the cover plate, 6 is the liquid injection pipe, A is the heat source area, and B is the heat dissipation condensation area. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0034] Embodiment 1

[0035] like Figures 1 to 3As shown, a large-area ultra-thin heat spreader includes a cover plate 5, a bottom plate 1, a liquid wick 2 and a supporting structure 3. A cavity in a negative pressure state is formed between the cover plate 5 and the bottom plate 1, and a phase change medium is filled in the cavity; the liquid wick 2 and the supporting structure 3 are both located in the cavity, the supporting structure 3 adopts a flat wire mesh and is used to support the cavity, and a steam channel 4 for steam flow is opened on the supporting structure 3; the cavity includes a heat source area A and a heat dissipation condensation area B, the phase change medium evaporates in the heat source area A and condenses in the heat dissipation condensation area B, and the steam channel 4 extends from the heat source area A to the heat dissipation condensation area.

[0036] The liquid wick 2 and the support structure 3 are sintered and fixed on the bottom plate 1. The cover plate 5 and the bottom plate 1 are welded to form a cavity between the two. The overall thickness of the large-area ultra-thin heat spreader is in the range of 0.95 to 1 mm, wherein the bottom plate 1 and the cover plate 5 are made of copper alloy and have a thickness of 0.5 mm. Chemical etching is used to form a groove with a depth of 0.35 mm. The groove between the bottom plate and the cover plate forms a cavity. The phase change medium can be deionized water, or acetone, ethanol and other working fluids. After the phase change medium evaporates into steam in the liquid wick 2, it flows and diffuses in the porous pores of the plane screen. The hollowing formed by cutting in the plane screen becomes the main steam channel 4 to ensure the mechanical bearing and the flow and diffusion of steam.

[0037] The steam channel 4 is in a rectangular strip shape and is formed by die cutting. One end of the steam channel 4 is located in the heat source area A, and the other end is located in the heat dissipation condensation area.

[0038] The material of the support structure 3 is copper, aluminum or nickel, the mesh pore diameter of the support structure 3 is greater than 500 μm, the number of steam channels 4 is multiple, and the spacing between adjacent steam channels 4 is greater than 3 times the sum of the mesh pore diameter and the wire diameter. This ensures the structural integrity of the planar wire mesh.

[0039] The support structure 3 is treated with hydrophobicity, and the liquid absorbent core 2 is treated with hydrophilicity. Existing hydrophobic treatment and hydrophilic treatment processes can be used. The use of the support structure 3 treated with hydrophobicity can reduce the adsorption of the liquid phase change medium on the plane screen, which is conducive to improving the flow and diffusion of steam in the porous structure of the plane screen and improving the temperature uniformity in the plane of the ultra-thin heat spreader. The liquid absorbent core 2 treated with hydrophilicity can ensure good capillary performance.

[0040] The liquid absorbent core 2 is a flat screen, and the diameter of the mesh pores of the liquid absorbent core is less than 10 μm.

[0041] The wick 2 and the support structure 3 are both woven from copper wires, and the diameter of the copper wires used in the wick 2 is smaller than that of the copper wires of the support structure 3. Specifically, the wick 2 uses a planar wire mesh with a small wire diameter of 0.05 mm, a mesh pore diameter of 77 μm and a thickness of 0.2 mm, and the planar wire mesh is woven from a large wire diameter copper wire with a wire diameter of 0.25 mm, and a mesh pore diameter of 1.02 mm.

[0042] The liquid absorbent core 2 and the supporting structure 3 are stacked in the thickness direction, and the sum of the thickness of the liquid absorbent core 2 and the supporting structure 3 is equal to the thickness of the cavity.

[0043] From the heat source area A to the heat dissipation condensation area, the width of the steam channel 4 gradually increases.

[0044] The steam channel 4 hollowed out on the support structure 3 starts from the heat source area A and the heat dissipation condensation area B. The phase change working fluid mainly evaporates in the heat source area A to form steam. The steam flows through the pores of the plane wire mesh and the steam channel 4 to the heat dissipation condensation area B. The steam flow velocity in the steam channel 4 will be increased. The gradually expanding steam channel 4 can appropriately reduce the flow velocity of the steam to avoid the high-speed steam flow from forming a backflow in the heat dissipation condensation area B, which is beneficial to reducing the pressure drop level of the steam and improving the thermal diffusivity of the steam. The steam condenses and releases heat due to cooling in the heat dissipation condensation area B, and is taken away by the external cooling method, thereby completing the rapid transfer of heat from the heat source. Under the capillary action of the liquid absorbent core 2, the condensed phase change working fluid returns to the heat source area A to continue to participate in the vapor-liquid cycle.

[0045] The above-mentioned method for preparing a large-area ultra-thin vapor chamber comprises the following steps:

[0046] S1, forming the cover plate 5 and the bottom plate 1, including the concave cavity and the liquid injection port thereon, by stamping, etching or machining;

[0047] S2, using a die-cutting method to process the outer contours of the absorbent core 2 and the support structure 3, as well as the steam channel 4 in the support structure 3;

[0048] S3, placing the wick 2, the supporting structure 3 and the bottom plate 1 in a reducing atmosphere and connecting them by high-temperature sintering, and then connecting this part to the cover plate 5 by a brazing process; specifically, placing the wick 2, the supporting structure 3 and the thin bottom plate 1 in a vacuum furnace in a reducing atmosphere at 780°C and sintering them together, placing the sintered thin cover plate 5 and the thin bottom plate 1 in a vacuum furnace and brazing them at 750°C, ensuring that the solder melts to seal the cover plate 5 and the bottom plate 1, inserting the injection tube 6 into the injection port and welding them by high-frequency welding.

[0049] S4, injecting phase change medium into the cavity between the cover plate 5 and the bottom plate 1, and performing degassing operation to ensure the vacuum degree of the inner cavity, and then performing sealing processing. The degassing operation can be performed by vacuuming, and the injection pipe 6 is continuously shortened and sealed during the process, and finally the injection port is sealed by argon arc welding.

[0050] Embodiment 2

[0051] like Figure 4 As shown, a battery thermal management system adopts a large-area ultra-thin vapor chamber in Example 1, including multiple energy storage batteries, and the heat source area A of the large-area ultra-thin vapor chamber is bonded to the energy storage batteries; the large-area ultra-thin vapor chamber is vertically placed between adjacent energy storage batteries. The heat generated by the energy storage battery enters the ultra-thin vapor chamber through the two bonding planes of the ultra-thin vapor chamber, wherein the hollowed-out steam flow channel 4 starts from the battery bonding area and ends at the heat dissipation condensation area B.

[0052] Embodiment 3

[0053] like Figure 5 As shown, a battery thermal management system adopts a large-area ultra-thin vapor chamber in Example 1, including multiple energy storage batteries, and the heat source area A of the large-area ultra-thin vapor chamber is bonded to the energy storage battery; the large-area ultra-thin vapor chamber is horizontally placed at the bottom of the energy storage battery. The heat generated by the energy storage battery enters the ultra-thin vapor chamber from the bonding plane of the ultra-thin vapor chamber, wherein the hollowed-out steam flow channel 4 starts from the battery bonding area and can end at the heat dissipation condensation area B and the boundary.

[0054] The above embodiments are preferred implementation modes of the invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A large-area ultra-thin heat spreader, characterized in that: It includes a cover plate, a bottom plate, a liquid wick and a supporting structure. A cavity in a negative pressure state is formed between the cover plate and the bottom plate, and a phase change medium is filled in the cavity. The liquid wick and the supporting structure are both located in the cavity. The supporting structure adopts a flat wire mesh and is used to support the cavity. A steam channel for steam flow is opened on the supporting structure. The cavity includes a heat source area and a heat dissipation condensation area. The phase change medium evaporates in the heat source area and condenses in the heat dissipation condensation area. The steam channel extends from the heat source area to the heat dissipation condensation area.

2. A large-area ultra-thin vapor chamber according to claim 1, characterized in that: The steam channel is in the shape of a rectangular strip and is formed by die cutting. One end of the steam channel is located in the heat source area, and the other end is located in the heat dissipation condensation area.

3. A large-area ultra-thin vapor chamber according to claim 1, characterized in that: The material of the support structure is copper, aluminum or nickel, the mesh pore diameter of the support structure is greater than 500 μm, the number of steam channels is multiple, and the spacing between adjacent steam channels is greater than 3 times the sum of the mesh pore diameter and the wire diameter.

4. A large-area ultra-thin vapor chamber according to claim 1, characterized in that: The support structure is treated with hydrophobic treatment and the wick is treated with hydrophilic treatment.

5. A large-area ultra-thin vapor chamber according to claim 1, characterized in that: The liquid absorbing core adopts a flat screen, and the mesh pore diameter of the liquid absorbing core is less than 10 μm.

6. A large-area ultra-thin vapor chamber according to claim 5, characterized in that: The liquid absorbing core and the supporting structure are both woven from copper wires, and the wire diameter of the copper wires used in the liquid absorbing core is smaller than the wire diameter of the copper wires of the supporting structure.

7. A large-area ultra-thin vapor chamber according to claim 1, characterized in that: The liquid absorbent core and the support structure are stacked in the thickness direction, and the sum of the thickness of the liquid absorbent core and the support structure is equal to the thickness of the cavity.

8. A large-area ultra-thin vapor chamber according to claim 1, characterized in that: From the heat source area to the heat dissipation and condensation area, the width of the steam channel gradually expands.

9. A method for preparing a large-area ultra-thin vapor chamber according to any one of claims 1 to 8, characterized in that: The following steps are included: S1, the cover plate and the base plate are manufactured by stamping, etching or machining; S2, using a die-cutting method to process the outer contours of the wick and the support structure, as well as the steam channel in the support structure; S3, placing the liquid wick, the support structure and the bottom plate in a reducing atmosphere and connecting them by high-temperature sintering, and then connecting the part to the cover plate by a brazing process; S4, injecting phase change medium into the cavity between the cover plate and the bottom plate, and performing degassing operation to ensure the vacuum degree of the inner cavity, and then performing sealing processing.

10. A battery thermal management system, using a large-area ultra-thin vapor chamber as claimed in any one of claims 1 to 8, characterized in that: It includes multiple energy storage batteries, and the heat source area of ​​the large-area ultra-thin heat spreader is attached to the energy storage batteries; The large-area ultra-thin heat spreader is placed vertically between adjacent energy storage batteries, or horizontally at the bottom of the energy storage battery.

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