Composite molding process of sheet molding compound for new energy liquid cooling plate

Abstract

The application discloses a sheet molding compound composite molding process of a new energy liquid cooling plate and relates to the technical field of battery thermal management. The process comprises the following steps: S1, preparing a heat-conducting MFP sheet material containing heat-conducting fillers and a low-filler structural MFP sheet material; S2, respectively molding an upper plate body and a lower plate body with a cooling liquid flow channel; S3, surface activation treatment; S4, coating a structural adhesive; and S5, aligning, adhering, pressing and curing into an integrated whole. The application realizes full MFP materialization of the liquid cooling plate body, and has the advantages of light weight, electrical insulation, reliable sealing and efficient process.

Description

Technical Field

[0001] This invention relates to the technical field of thermal management of new energy batteries, and in particular to a composite molding process for a new energy liquid cooling plate using molding fiber-reinforced plastic (MFP). Background Technology

[0002] Liquid cooling plates are core components of the thermal management system for power batteries in new energy vehicles. Through the circulation of coolant within the channels of the liquid cooling plate, heat generated by the battery cells during operation is carried away, maintaining the battery pack within a suitable temperature range and ensuring battery safety, consistency, and lifespan. Liquid cooling plates are typically located below the battery module, either in direct contact with the battery cells or indirectly through a thermally conductive interface material. Therefore, liquid cooling plates not only need to possess high thermal conductivity but also meet the battery pack's requirements for electrical insulation, corrosion resistance, and lightweight design.

[0003] Currently, existing liquid cooling plates for battery packs have the following main shortcomings in terms of material selection and manufacturing process:

[0004] Firstly, Chinese patent CN119381655A discloses "a composite material box bottom plate and its processing technology", which uses MFP composite material to mold the battery box bottom plate, but the liquid cooling plate is still made separately using aluminum alloy brazed stamping plate. Then, the aluminum alloy liquid cooling plate and the MFP box bottom plate are assembled by bolt riveting and adhesive bonding. However, this solution has the following defects: (1) The liquid cooling plate body is still a metal material, and the liquid cooling plate itself is not lightweight and electrically insulating; (2) The MFP box bottom plate and the aluminum alloy liquid cooling plate are made of different materials. The two are assembled by bolts and adhesive, which has the problem of insufficient interface bonding reliability. Under long-term vibration and thermal cycling conditions, the bolt connection is easy to loosen, resulting in coolant leakage; (3) The assembly process is complicated. It is necessary to manufacture the MFP bottom plate and the metal liquid cooling plate separately and then perform secondary assembly, resulting in low production efficiency.

[0005] Secondly, Chinese patent CN224153490U discloses "a non-metallic parallel liquid-cooled battery housing," in which the battery housing is made of MFP composite material, but the liquid cooling plate is still an inverted T-shaped cooling plate made of aluminum alloy, which is fixed to the MFP housing base by tenon joints. However, this solution also has the problem that the liquid cooling plate body is made of metal, and the MFP housing and the metal cooling plate are connected by dissimilar materials. Moreover, the manufacturing process of the inverted T-shaped aluminum alloy cooling plate is completely different from the molding process of the MFP housing, making integrated production impossible.

[0006] Thirdly, Chinese patent CN117677128A discloses "a composite liquid cooling plate for heat dissipation of heat-generating components and its manufacturing method". It uses high thermal conductivity powder and binder to hot press and form a composite substrate, and coils copper tubes into the pipe grooves in the substrate to form a liquid cooling pipeline. However, this solution has the following limitations: (1) The liquid cooling pipeline relies on metal copper tubes. The bending and arrangement of copper tubes restrict the design freedom of the flow channel and make it difficult to achieve a complex flow channel topology; (2) The copper tubes and the composite substrate are only fixed by embedding with adhesive. Under the internal pressure of the coolant and the cycle of thermal expansion and contraction, the interface between the copper tubes and the substrate is prone to gaps, which can lead to leakage; (3) This solution is aimed at small-sized heat-generating components in the aerospace field. Its base layer is formed by filling high thermal conductivity powder with a lost mold. The process is complicated and the production efficiency is low. It is not suitable for the large-scale production needs of liquid cooling plates for new energy vehicle battery packs.

[0007] In summary, existing battery pack liquid cooling plates suffer from problems such as large weight of metal materials, insufficient reliability of heterogeneous connection between MFP and metal, metal pipelines limiting the design freedom of flow channels, and complex processes of composite liquid cooling plates that are not suitable for large-scale production. In particular, there is a lack of a new energy liquid cooling plate manufacturing process that uses MFP composite materials for the entire liquid cooling plate body, with the upper and lower plates molded separately and then bonded together in one piece, and is suitable for large-scale production. Summary of the Invention

[0008] The purpose of this invention is to provide a sheet molding compound process for new energy liquid cooling plates to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides a sheet molding compound composite molding process for a new energy liquid cooling plate, which adopts the following technical solution:

[0010] A sheet molding compound composite molding process for a new energy liquid cooling plate includes the following steps:

[0011] S1: Prepare thermally conductive MFP sheets and structural MFP sheets, wherein the thermally conductive MFP sheets contain thermally conductive fillers, and the volume percentage of the thermally conductive fillers in the structural MFP sheets does not exceed 10% of the volume percentage of the thermally conductive fillers in the thermally conductive MFP sheets, and the volume percentage of the thermally conductive fillers in the structural MFP sheets does not exceed 2.5%;

[0012] S2: The thermally conductive MFP sheet is placed in the first mold for compression molding to obtain the upper plate; the structural MFP sheet is placed in the second mold for compression molding to obtain the lower plate. The cavity of the second mold is provided with a flow channel forming structure so that the lower plate is integrally molded to form a coolant flow channel.

[0013] S3: Perform surface activation treatment on the lower surface of the upper plate and / or the upper surface of the lower plate;

[0014] S4: Apply structural adhesive to the lower surface of the upper plate and / or the upper surface of the lower plate;

[0015] S5: Align and attach the upper plate to the lower plate, so that the lower surface of the upper plate is bonded to the upper surface of the lower plate by the structural adhesive;

[0016] When the upper plate and the lower plate are aligned and bonded, a limiting structure is provided between them to control the final cured thickness of the structural adhesive to be 0.1mm to 0.3mm.

[0017] After being pressurized and cured, the upper plate and the lower plate are fixedly connected as one unit to obtain the liquid cooling plate.

[0018] By adopting the above technical solution, this invention divides the liquid cooling plate into an upper plate and a lower plate, which are molded separately. The upper plate uses a thermally conductive MFP sheet containing thermally conductive filler, while the lower plate uses a structural MFP sheet with a very low content of thermally conductive filler. Coolant channels are integrally molded in the cavity, achieving complete MFP fabrication of the liquid cooling plate body and avoiding the reliability issues of heterogeneous connections between the MFP housing and the metal liquid cooling plate in existing technologies. Simultaneously, after molding the upper and lower plates separately, they are joined together through surface activation treatment and structural adhesive bonding. The coolant channels are formed in one step during the molding of the lower plate, eliminating the need for embedded metal pipes. Furthermore, the differentiated design of the thermally conductive MFP sheet and the structural MFP sheet allows the upper plate to balance thermal conductivity and electrical insulation, while the lower plate balances structural strength and channel sealing.

[0019] Preferably, in step S2, the thermally conductive filler in the thermally conductive MFP sheet is distributed in a gradient along the thickness direction of the upper plate, and the content of thermally conductive filler on the side of the upper plate closer to the battery cell is higher than the content of thermally conductive filler on the side closer to the lower plate, so that the thermal conductivity of the upper plate is ≥3W / m·K.

[0020] By adopting the above technical solution, the gradient distribution of the thermally conductive filler results in a higher thermal conductivity on the side of the upper plate closer to the battery cell, which facilitates the rapid transfer of heat from the battery cell to the liquid cooling plate. Conversely, the lower content of the thermally conductive filler on the side closer to the lower plate improves the bonding strength of the structural adhesive between the upper and lower plates, avoiding the problem of insufficient MFP matrix resin content due to excessive thermally conductive filler content, which could affect the bonding interface strength. This gradient distribution achieves an optimal balance between thermal conductivity and bonding strength.

[0021] Preferably, in step S2, the lower surface of the upper plate is provided with a first joining structure, and the upper surface of the lower plate is provided with a second joining structure, wherein the first joining structure and the second joining structure are concave-convex mating structures; in step S5, when the upper plate and the lower plate are aligned and fitted together, the first joining structure and the second joining structure are interlocked.

[0022] By adopting the above technical solution, the concave-convex mating structure provides mechanical positioning and initial fixing functions when the upper and lower plates are aligned and bonded, preventing relative slippage and misalignment of the upper and lower plates during the pressure curing process after applying structural adhesive, and ensuring the alignment accuracy of the flow channel cavity between the upper and lower plates; at the same time, the concave-convex mating structure increases the effective contact area of ​​the bonding interface between the upper and lower plates, further improving the bonding strength.

[0023] Preferably, the first joining structure is a rib, and the second joining structure is a groove; after the rib and the groove are fitted together, an annular sealing structure is formed around the coolant flow channel, and the cross-sections of the rib and the groove are both set to arc shape.

[0024] By adopting the above technical solution, after the rib and groove are fitted together, structural adhesive fills the gap between the rib and groove, forming a continuous sealing ring around the coolant flow channel. Under the action of coolant internal pressure, the higher the internal pressure, the tighter the fit between the rib and groove, forming a self-tightening sealing effect, which significantly improves the pressure resistance and sealing reliability of the liquid cooling plate and reduces the risk of coolant leakage.

[0025] Preferably, in step S2, the lower plate is also integrally molded with an inlet and outlet structure, the inlet and outlet structure including an inlet nozzle and an outlet nozzle, the inlet nozzle and the outlet nozzle being connected to both ends of the coolant flow channel respectively.

[0026] By adopting the above technical solution, the inlet and outlet structure is integrally molded with the lower plate, eliminating the need for subsequent welding or threaded connection of metal nozzles. This avoids the risk of leakage at the joint of dissimilar materials, while reducing assembly steps and improving production efficiency and product sealing reliability.

[0027] Preferably, in step S2, a turbulence structure is integrally molded inside the coolant flow channel, and the turbulence structure is a plurality of protrusions or turbulence columns spaced apart inside the flow channel.

[0028] By adopting the above technical solution, the turbulence structure causes the coolant to flow turbulently in the flow channel, which destroys the thermal boundary layer near the flow channel wall in the laminar flow state, significantly improves the convective heat transfer coefficient of the inner wall of the flow channel, and enables the cell heat to be transferred to the coolant more efficiently, reducing the temperature non-uniformity inside the battery pack.

[0029] Preferably, in step S3, the surface activation treatment is plasma treatment or corona treatment.

[0030] By adopting the above technical solutions, plasma treatment or corona treatment breaks the resin molecular chains on the surface of MFP sheets to generate active groups, which significantly improves the surface energy and wettability of the MFP surface, allowing the subsequently applied structural adhesive to spread and penetrate more fully into the microstructure of the MFP surface, forming a stronger interfacial bond.

[0031] Preferably, in step S5, the pressure curing is carried out under vacuum conditions, with a vacuum degree of -0.08MPa to -0.1MPa.

[0032] By adopting the above technical solution, the vacuum condition eliminates air bubbles and volatiles at the structural adhesive layer and bonding interface, avoids air bubbles remaining in the adhesive layer and forming local weaknesses, ensures the continuity and density of the bonding interface between the upper and lower plates, and further improves the pressure resistance, sealing performance and long-term reliability of the liquid cooling plate.

[0033] Preferably, in step S2, the upper plate and the lower plate are respectively molded to an incompletely cured state. The incompletely cured state refers to a degree of curing of 50% to 75% as measured by differential scanning calorimetry (DSC), and the surfaces of the upper plate and the lower plate still retain incompletely cross-linked active resin groups. In step S5, the pressure curing is performed by bonding the incompletely cured upper plate and the lower plate together, and then applying pressure and heating for secondary curing. This causes the active resin groups on the surfaces of the upper plate and the lower plate to undergo a cross-linking reaction with the structural adhesive, forming an interpenetrating network structure of resin and structural adhesive at the bonding interface, so that the two are chemically cross-linked and bonded together.

[0034] By adopting the above technical solution, the surface of the MFP board in the incompletely cured state still contains incompletely cross-linked active resin groups. During the S5 secondary curing process, the active resin groups on the surface of the upper and lower boards undergo a cross-linking reaction with the structural adhesive, forming an interpenetrating network structure of MFP resin and structural adhesive at the bonding interface. This upgrades the connection between the upper and lower boards from simple adhesive bonding to chemical cross-linking bonding, significantly improving the strength and durability of the bonding interface.

[0035] This invention achieves full MFP composite material for the liquid cooling plate body through a combination of processes including separate molding of upper and lower plates, differentiated MFP material design, surface activation treatment, and structural adhesive bonding. It offers advantages such as lightweight, electrical insulation, corrosion resistance, optimized thermal conductivity and structural partitioning, high sealing reliability, and simple and efficient processing, making it suitable for large-scale production of liquid cooling plates for new energy vehicle battery packs. Furthermore, by molding the upper and lower plates to an incompletely cured state followed by secondary curing, the active resin groups on the surfaces of the upper and lower plates undergo chemical cross-linking with the structural adhesive, forming an interpenetrating network structure at the bonding interface. This significantly improves the bonding strength and long-term durability of the bonding interface. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the sheet molding compound composite molding process for the new energy liquid cooling plate in an embodiment of the present invention.

[0037] Figure 2 This is a three-dimensional structural diagram of the upper plate and the lower plate in an embodiment of the present invention.

[0038] Figure 3 This is a schematic cross-sectional view of the overall structure of the liquid cooling plate in an embodiment of the present invention.

[0039] Explanation of reference numerals in the attached drawings: 10, upper plate; 11, first joint structure; 20, lower plate; 21, coolant flow channel; 22, second joint structure; 23, turbulence structure; 24, inlet / outlet structure; 30, structural adhesive; 40, thermally conductive filler. Detailed Implementation

[0040] The following is in conjunction with the appendix Figure 1-3 The present invention will be described in further detail below.

[0041] Example 1

[0042] like Figures 1 to 3 As shown, this embodiment provides a sheet molding compound composite molding process for a new energy liquid cooling plate, including the following steps.

[0043] S1: Preparation of MFP sheet material.

[0044] Preparation of thermally conductive MFP sheet material: Epoxy vinyl ester resin, styrene, chopped glass fibers (25 mm in length, 30% by mass) and thermally conductive filler are mixed, wherein the thermally conductive filler is aluminum nitride powder (average particle size 10 μm), and the volume ratio of the thermally conductive filler is 25% of the total volume of the MFP sheet material. The mixture is formed into sheets by an MFP sheeting machine to obtain the thermally conductive MFP sheet material.

[0045] Preparation of structural MFP sheets: Epoxy vinyl ester resin, styrene, chopped glass fibers (25 mm in length, 50% by mass) and a small amount of filler (calcium carbonate, 5% by volume) are mixed. The volume percentage of the thermally conductive filler in the structural MFP sheet is less than 10% of the volume percentage of the thermally conductive filler in the thermally conductive MFP sheet, i.e., no more than 2.5% of the total volume of the structural MFP sheet. The mixture is then formed into sheets using an MFP sheeting machine to obtain the structural MFP sheet.

[0046] S2: Molding the upper and lower plates separately.

[0047] The thermally conductive MFP sheet was cut and placed in the first mold, and then molded for 120 seconds at a temperature of 150℃ and a pressure of 15MPa to obtain the upper plate 10. The thickness of the upper plate 10 is 3.0mm.

[0048] The structural MFP sheet is cut and placed in the second mold. The cavity of the second mold has a flow channel forming structure (corresponding to the shape of the coolant flow channel 21). It is molded for 180 seconds at a temperature of 150℃ and a pressure of 15MPa to obtain the lower plate 20. The lower plate 20 has a thickness of 5.0mm, and the upper surface of the lower plate 20 has an integrally formed coolant flow channel 21. The coolant flow channel 21 is a serpentine flow channel with a depth of 2.5mm and a width of 8mm.

[0049] S3: Surface activation treatment.

[0050] The upper surface (including the flow channel surface) of the lower plate 20 is subjected to plasma treatment with a power of 500W and a treatment time of 30s, thereby increasing the surface energy of the upper surface of the lower plate 20 from about 38mN / m to about 65mN / m.

[0051] S4: Apply structural adhesive.

[0052] An epoxy resin structural adhesive 30 is applied to the upper surface of the lower plate 20, with an application amount of 200 g / m².

[0053] S5: Alignment bonding and pressure curing.

[0054] The upper plate 10 and the lower plate 20 are aligned and bonded together, with the lower surface of the upper plate 10 and the upper surface of the lower plate 20 bonded together using structural adhesive 30. A limiting structure is provided between them. In this embodiment, the limiting structure consists of multiple equal-height limiting protrusions on the upper surface of the lower plate 20. The height of each equal-height limiting protrusion is 0.2mm (which is equal to the designed curing thickness of the structural adhesive 30). The multiple equal-height limiting protrusions are distributed at intervals along the outer periphery of the coolant flow channel 21. During the pressure curing process, the top of the equal-height limiting protrusions abuts against the lower surface of the upper plate 10, preventing the upper and lower plates from getting closer together, thereby controlling the final curing thickness of the structural adhesive 30 to 0.2mm. The bonded components are placed in a vacuum hot press and pressurized in stages: first, pre-press at 0.15MPa for 4 minutes to allow the structural adhesive 30 to spread initially and expel gas from the bonding interface; then increase the pressure to 0.5MPa and pressurize under vacuum of -0.09MPa and temperature of 120℃ for 60 minutes to fix the upper plate 10 and the lower plate 20 together with the structural adhesive 30, thus obtaining the liquid cooling plate.

[0055] In this embodiment, the total thickness of the liquid cooling plate is approximately 8.0 mm. Compared with an aluminum alloy liquid cooling plate of the same specifications (thickness approximately 5.0 mm, density 2.7 g / cm³), the density of the MFP liquid cooling plate in this embodiment is approximately 1.9 g / cm³, resulting in a weight reduction of approximately 30%, while also possessing excellent electrical insulation and corrosion resistance.

[0056] The thermal conductivity of the upper plate prepared in this embodiment was tested. The test was conducted according to ASTM D 5470 standard, using the steady-state heat flow method. The sample thickness was 3.0 mm, the test temperature was 25 °C, the heat flow rate was 5 W, and the temperature difference ΔT > 10 K. The measured thermal conductivity of the upper plate in this embodiment was 4.2 W / (m·K), which meets the requirement of ≥3 W / (m·K).

[0057] Example 2

[0058] The difference between this embodiment and Embodiment 1 is that the upper plate adopts a gradient distribution of thermally conductive filler, and the upper and lower plates are provided with a concave-convex mating structure.

[0059] Specifically, when preparing the thermally conductive MFP sheet in S1, a layered laying method is adopted, so that the volume ratio of the thermally conductive filler on the side closer to the battery cell is 35% and the volume ratio of the thermally conductive filler on the side closer to the lower plate is 15%, forming a gradient distribution along the thickness direction.

[0060] In S2, the cavity of the first mold has a raised rib on the lower surface of the upper plate 10 as a first joint structure 11, and the cavity of the second mold has a groove on the upper surface of the lower plate 20 as a second joint structure 22. The cross-section of the raised rib is arc-shaped, with a height of 0.8 mm and a width of 1.2 mm; the depth and width of the groove are adapted to the raised rib.

[0061] In S5, when the upper plate 10 and the lower plate 20 are aligned and fitted, the first joint structure 11 is embedded in the second joint structure 22, and the structural adhesive 30 is filled in the mating gap to form an annular sealing structure surrounding the coolant flow channel 21.

[0062] The remaining steps and parameters are the same as in Example 1, and will not be repeated here.

[0063] In this embodiment, the gradient distribution of the thermally conductive filler results in a higher thermal conductivity on the side of the upper plate 10 closer to the battery cell, which is beneficial for the rapid transfer of heat from the battery cell. The thermally conductive filler content is lower on the side closer to the bonding interface, ensuring that the structural adhesive at the bonding interface can fully wet and penetrate the MFP surface, resulting in higher bonding strength. The interlocking of the ribs and grooves provides both mechanical positioning and self-tightening sealing functions.

[0064] Example 3

[0065] The difference between this embodiment and Embodiment 1 is that the lower plate is integrally molded and has an inlet / outlet structure and a turbulence structure.

[0066] Specifically, the cavity of the second mold is provided with inlet / outlet forming structures and turbulence forming structures. After molding, the lower plate 20 is integrally formed with inlet / outlet structures 24, including an inlet nozzle and an outlet nozzle, which are respectively connected to both ends of the coolant flow channel 21. Multiple turbulence columns 23 are integrally molded inside the coolant flow channel 21 as turbulence structures. The turbulence columns 23 are cylindrical, with a diameter of 3 mm and a height of 1.5 mm, and are evenly arranged at 15 mm intervals along the length of the flow channel.

[0067] In S3, the lower surface of the upper plate 10 and the upper surface of the lower plate 20 are both subjected to plasma treatment.

[0068] In S4, structural adhesive 30 is applied to the lower surface of the upper plate 10 and the upper surface of the lower plate 20.

[0069] The remaining steps and parameters are the same as in Example 1, and will not be repeated here.

[0070] In this embodiment, the inlet and outlet structures are integrally molded with the lower plate, eliminating the need for subsequent metal nozzle connections and removing the potential leakage risk at the junction of dissimilar materials. The turbulence column 23 generates turbulence in the coolant within the flow channel, improving the convective heat transfer coefficient and reducing temperature unevenness inside the battery pack.

[0071] Example 4

[0072] The difference between this embodiment and Embodiment 1 is that it uses incomplete curing molding and secondary co-curing processes.

[0073] Specifically, in S2, the upper plate 10 and the lower plate 20 are molded at a temperature of 135℃~145℃ and a pressure of 10MPa~14MPa for 50s~90s until they are incompletely cured (the degree of curing is determined by differential scanning calorimetry (DSC) as follows: Take the molded MFP plate sample and heat it from room temperature to 250℃ at a heating rate of 10℃ / min. Measure its residual heat release ΔHr and compare it with the total heat release ΔHtotal of the fully cured sample (the sample cured at 160℃ for 60min with the same formula). The degree of curing is calculated as (1-ΔHr / ΔHtotal)×100%, where ΔHr is the residual heat release and ΔHtotal is the total heat release of the fully cured sample. The degree of curing is controlled to be 50%~75%. At this time, the surface of the MFP plate still contains incompletely cross-linked active groups.

[0074] In step S5, the partially cured upper plate 10 and lower plate 20 are aligned and bonded together using structural adhesive 30, and then subjected to a secondary curing process of 150-210 minutes at a temperature of 150-170°C and a pressure of 0.6-1.0 MPa. During the secondary curing process, the active resin groups on the surfaces of the upper plate 10 and lower plate 20 undergo a cross-linking reaction with the structural adhesive 30, forming an interpenetrating network structure at the bonding interface. The remaining steps and parameters are the same as in Example 1 and will not be repeated here.

[0075] In this embodiment, the incomplete curing co-crosslinking process elevates the connection between the upper and lower plates from simple adhesive bonding to chemical crosslinking, significantly improving the strength and durability of the bonding interface. This is suitable for applications requiring higher reliability of liquid cooling plate sealing. It should be noted that the molding time in the incompletely cured state needs to be pre-calibrated using DSC based on the specific formulation of the MFP sheet material (resin type, initiator system, and dosage). In actual production, the degree of curing can be controlled within the above range by adjusting the molding temperature and holding time. If the degree of curing is below 50%, the interfacial crosslinking density will be insufficient after secondary curing; if the degree of curing is above 75%, the surface-active groups will be excessively consumed, weakening the chemical bonding effect with the structural adhesive. Therefore, controlling the degree of curing within the range of 50% to 75% is the preferred choice.

[0076] Example 5

[0077] The difference between this embodiment and Embodiment 1 is that the surface activation treatment method is corona treatment.

[0078] Specifically, in S3, the upper surface of the lower plate 20 is subjected to corona treatment. The distance between the corona electrode and the upper surface of the lower plate 20 is 5mm, the treatment speed is 5m / min, and the corona power is 3kW.

[0079] The remaining steps and parameters are the same as in Example 1, and will not be repeated here.

[0080] In this embodiment, the investment cost of the corona treatment equipment is lower than that of plasma treatment, making it more suitable for the surface activation treatment needs of large-scale continuous production lines.

[0081] In summary, this invention achieves full MFP composite material material for the liquid cooling plate body through a combination of processes including separate molding of upper and lower plates, differentiated MFP material design, surface activation treatment, and structural adhesive bonding. It has the advantages of lightweight, electrical insulation, corrosion resistance, optimized thermal conductivity and structural partitioning, high sealing reliability, and simple and efficient process, making it suitable for large-scale production of liquid cooling plates for new energy vehicle battery packs.

[0082] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A sheet molding compound composite molding process for a new energy liquid cooling plate, comprising the following steps: S1: Prepare thermally conductive MFP sheets and structural MFP sheets, wherein the thermally conductive MFP sheets contain thermally conductive fillers, and the volume percentage of the thermally conductive fillers in the structural MFP sheets does not exceed 10% of the volume percentage of the thermally conductive fillers in the thermally conductive MFP sheets, and the volume percentage of the thermally conductive fillers in the structural MFP sheets does not exceed 2.5%; S2: The thermally conductive MFP sheet is placed in the first mold for compression molding to obtain the upper plate; the structural MFP sheet is placed in the second mold for compression molding to obtain the lower plate. The cavity of the second mold is provided with a flow channel forming structure so that the lower plate is integrally molded to form a coolant flow channel. S3: Perform surface activation treatment on the lower surface of the upper plate and / or the upper surface of the lower plate; S4: Apply structural adhesive to the lower surface of the upper plate and / or the upper surface of the lower plate; S5: Align and attach the upper plate to the lower plate, so that the lower surface of the upper plate is bonded to the upper surface of the lower plate by the structural adhesive; When the upper plate and the lower plate are aligned and bonded, a limiting structure is provided between them to control the final cured thickness of the structural adhesive to be 0.1mm to 0.3mm. The limiting structure is any one or a combination of the following: (a) A height-equal boss is provided on the joint surface of the upper plate or the lower plate, wherein the height of the height-equal boss is equal to the design thickness of the structural adhesive; (b) An adhesive reservoir provided on the joint surface of the upper or lower plate is used to accommodate excess structural adhesive that overflows during the pressure curing process; After being pressurized and cured, the upper plate and the lower plate are fixedly connected as one unit to obtain the liquid cooling plate.

2. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 1, characterized in that: In step S2, the thermally conductive filler in the thermally conductive MFP sheet is distributed in a gradient along the thickness direction of the upper plate. The thermally conductive filler content on the side of the upper plate closer to the battery cell is higher than that on the side closer to the lower plate, so that the thermal conductivity of the upper plate is ≥3W / m·K.

3. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 1, characterized in that: In step S2, the lower surface of the upper plate is provided with a first joining structure, and the upper surface of the lower plate is provided with a second joining structure. The first joining structure and the second joining structure are concave-convex mating structures. In step S5, when the upper plate and the lower plate are aligned and fitted together, the first joining structure and the second joining structure are interlocked.

4. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 3, characterized in that: The first joining structure is a rib, and the second joining structure is a groove. After the rib and the groove are fitted together, they form an annular sealing structure surrounding the coolant flow channel. The cross-sections of the rib and the groove are both set to arc shape.

5. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 1, characterized in that: In step S2, the lower plate is also integrally molded with an inlet and outlet structure, which includes an inlet nozzle and an outlet nozzle, and the inlet nozzle and the outlet nozzle are respectively connected to the two ends of the coolant flow channel.

6. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 1, characterized in that: In step S2, a turbulence structure is integrally molded inside the coolant flow channel. The turbulence structure consists of multiple protrusions or turbulence columns spaced apart inside the flow channel.

7. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 1, characterized in that: In step S3, the surface activation treatment is either plasma treatment or corona treatment.

8. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 1, characterized in that: In step S5, the pressure curing is carried out under vacuum conditions, with a vacuum degree of -0.08MPa to -0.1MPa.

9. The sheet molding compound composite molding process for the new energy liquid cooling plate according to claim 1, characterized in that: In step S2, the upper plate and the lower plate are respectively molded to an incompletely cured state. The incompletely cured state means that the degree of curing measured by differential scanning calorimetry (DSC) is 50% to 75%, and the surfaces of the upper plate and the lower plate still retain incompletely cross-linked active resin groups. The pressure curing in S5 involves bonding the incompletely cured upper plate to the lower plate and then applying pressure and heating for secondary curing. This causes the active resin groups on the surfaces of the upper and lower plates to cross-link with the structural adhesive, forming an interpenetrating network structure of resin and structural adhesive at the bonding interface, thus chemically bonding the two together.

10. A new energy liquid-cooled plate, characterized in that, It is prepared by the sheet molding compound composite molding process as described in any one of claims 1 to 9.

Images