Battery pack lower box, preparation method and battery pack

Abstract

This invention relates to a lower housing of a battery pack, an assembly method, and a battery pack. The lower housing body is made of fiber-reinforced thermoplastic resin-based composite material. The supporting surface of the lower housing body for supporting the battery module has multiple spaced parallel bearing areas. Along the length of the lower housing body, the bearing areas have multiple spaced grooves. The grooves contain a mesh rib structure integrally connected to the lower housing body, so that the bearing areas have multiple alternating planar support areas and mesh rib areas. The invention also includes a liquid-cooled plate assembly made of metal material. The liquid-cooled plate assembly is fixed to the lower housing body through pre-embedded metal connectors. The liquid-cooled plate assembly includes multiple liquid-cooled plates corresponding one-to-one with the bearing areas. The bottom surface of the liquid-cooled plates is attached to the planar support areas for support. The lower housing of this invention has a strong load-bearing capacity.

Description

Technical Field

[0001] This invention relates to the field of energy storage battery technology, specifically to a battery pack lower casing, its preparation method, and the battery pack itself. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Currently, the mainstream battery pack solutions for energy storage batteries are metal lower casing and composite material lower casing.

[0004] Metal lower casings have low material costs but are heavy, resulting in low overall energy density and high transportation and installation costs; they also have poor corrosion resistance, requiring additional anti-corrosion treatment processes; and the composite materials process involves multiple cutting and welding steps, leading to high manufacturing costs.

[0005] Composite material solutions often utilize thermosetting resins such as epoxy resin and polyurethane, combined with glass fiber reinforcement, and manufactured through molding or hand lay-up processes. This approach achieves lightweight and corrosion resistance, but thermosetting materials themselves have drawbacks such as non-recyclability, poor toughness, susceptibility to microcracks after impact, long production cycles, and inability to be repaired later.

[0006] The lower housing, made of fiber-reinforced thermoplastic resin through molding, overcomes the defects of metal and thermosetting resin lower housings. However, energy storage batteries used in photovoltaic, wind power and other industrial fields have large capacity and therefore large mass, and the lower housing bears a large weight. When using fiber-reinforced thermoplastic resin to make the lower housing, how to ensure the load-bearing capacity of the lower housing is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a battery pack lower casing, assembly method, and battery pack, thereby solving the problem of insufficient load-bearing capacity faced by the lower casing made of fiber-reinforced thermoplastic resin material when energy storage batteries are used in industrial fields.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, embodiments of the present invention provide a lower housing for a battery pack, including a lower housing body. The lower housing body is made of fiber-reinforced thermoplastic resin-based composite material. The supporting surface of the lower housing body for supporting the battery module is provided with multiple spaced parallel bearing areas. Along the length direction of the lower housing body, the bearing areas are provided with multiple spaced grooves. The grooves are provided with a mesh rib structure integrally connected to the lower housing body so that the bearing areas have multiple alternating planar support areas and mesh rib areas. It also includes a liquid cooling plate assembly made of metal materials. The liquid cooling plate assembly is fixed to the lower housing body through metal connectors embedded in the lower housing body. The liquid cooling plate assembly includes multiple liquid cooling plates that correspond one-to-one with the load-bearing area. The bottom surface of the liquid cooling plate is attached to the planar support area and supported by the planar support area.

[0009] Optionally, one end of a plurality of liquid cooling plates is connected to a first connecting cavity, and the other end is connected to a second connecting cavity. The first connecting cavity has a partition to divide the space inside the first connecting cavity into a first chamber and a second chamber. The flow channels of some liquid cooling plates are connected to the first chamber, and the flow channels of the remaining liquid cooling plates are connected to the second chamber. The first chamber is connected to an inlet pipe, and the second chamber is connected to an outlet pipe.

[0010] Optionally, the lower housing body includes a bottom housing wall and a side housing wall set at the edge of the bottom housing wall. The top surface of the bottom housing wall serves as a support surface. The inlet pipe and the outlet pipe both pass through the corresponding side housing wall and are provided with a sealing element between them. Furthermore, the seal includes a metal skeleton, with a flexible sealing ring wrapped around its outer periphery.

[0011] Optionally, the second connecting cavity is fixedly connected to the lower housing body through a metal connector in the lower housing body.

[0012] Optionally, the mesh rib structure includes multiple intersecting first ribs and second ribs, with the first ribs and second ribs integrally connected and integrally connected to the lower housing body.

[0013] Optionally, the liquid cooling plate includes a bottom plate and a top cover plate, with multiple flow channel plates provided between the bottom plate and the top cover plate, and cooling medium flow channels formed between adjacent flow channel plates; Optionally, a stiffening plate may be provided between the flow channel plate and the top cover plate and / or the bottom plate.

[0014] Optionally, in the liquid cooling plate, the distribution density of the flow channel plate in the area corresponding to the tab of the battery module is greater than the distribution density in the other areas to form a flow channel with a width smaller than that in the other areas, and the distribution density of the flow channel plate in the middle area of ​​the liquid cooling plate is less than the distribution density in the other areas to form a flow channel with a width greater than that in the other areas.

[0015] Optionally, in fiber-reinforced thermoplastic resin-based composite materials, the reinforcing fiber is glass fiber, carbon fiber, or basalt fiber, and the resin-based material is flame-retardant PP material or flame-retardant PA material.

[0016] Optionally, the planar support area is bonded and fixed to the bottom surface of the liquid cooling plate with structural adhesive.

[0017] Secondly, embodiments of the present invention provide a method for preparing the lower casing of the battery pack as described in the first aspect, comprising the following steps: The set weight of resin-based material is heated to the first set temperature once; Reinforcing fibers are added to the resin-based material and then heated a second time to a second set temperature to complete the preparation of the preform; After the blank is cut, the cut blank is sent into a mold pre-inserted with metal connectors. The lower box body is formed by compression molding.

[0018] After the lower housing body is cooled and demolded, the liquid cooling plate assembly is placed inside the lower housing of the battery pack and fixed to the lower housing body with metal connectors.

[0019] Thirdly, embodiments of the present invention provide a battery pack having the lower housing of the battery pack described in the first aspect.

[0020] The beneficial effects of this invention are as follows: 1. The lower housing of the battery pack of the present invention is made of fiber-reinforced thermoplastic resin-based composite material. The load-bearing area forms alternating planar support areas and mesh rib areas. On the one hand, different mesh rib areas can set the parameters of the mesh rib structure according to the load size of different areas of the battery pack, forming an adaptive distribution of stiffness and strength, avoiding redundancy in equal strength design. On the other hand, the alternating planar support areas and mesh rib areas form a cooperative force-bearing system. The planar support areas can provide lateral support for the mesh rib structure, suppressing the instability of the mesh rib structure. At the same time, the mesh rib structure can provide boundary constraints for the planar support areas, reducing the flexural deformation of the planar support areas under large pressure. The structure of planar support areas plus mesh rib areas can significantly improve the moment of inertia of the lower housing body. Compared with the pure planar load-bearing area of ​​the lower housing body, the bending stiffness can be greatly improved, significantly improving the load-bearing capacity. Compared with the pure mesh rib structure in the load-bearing area, the stability of the structure is improved, the manufacturing qualification rate is increased, and material waste is reduced.

[0021] 2. The battery pack housing of the present invention employs alternating planar support areas and mesh rib areas. The planar support areas also provide a large bonding area with the liquid cooling plate. While the liquid cooling plate is fixed to the lower housing body through metal connectors, it can also be bonded and fixed to the planar support areas. Even when the connection between the metal connectors and the liquid cooling plate becomes loose, the connection strength between the liquid cooling metal plate and the lower housing body can still be guaranteed. At the same time, the bonding between the liquid cooling metal plate and the planar support areas increases the rigidity of the lower housing body and improves its load-bearing capacity. Therefore, by employing alternating planar support areas and mesh rib areas, the load-bearing capacity of the lower housing can be increased through the structure itself, and it can also be combined with the liquid cooling plate to increase the load-bearing capacity of the lower housing in reverse by utilizing the structure of the liquid cooling plate.

[0022] 3. In the lower housing of the battery pack of the present invention, the liquid cooling plate is fixed to the lower housing body through a metal connector pre-embedded in the lower housing body. Compared with the method of slotting the liquid cooling plate and allowing the resin material to flow into the slot during molding to fix the liquid cooling plate and the lower housing body, this method not only utilizes the excellent thermal conductivity of the metal material, but also avoids the stress problem caused by the difference in thermal expansion coefficient between composite materials and metals during long-term thermal cycling.

[0023] 4. The lower housing of the battery pack of the present invention includes a liquid cooling plate comprising a bottom plate, an upper cover plate, and a flow channel plate disposed between the bottom plate and the upper cover plate. The flow channel plate plays a supporting role and has good load-bearing capacity. It does not require additional external support beams or a significant increase in the thickness of the liquid cooling plate, thus solving the problem in the prior art that the liquid cooling plate cannot simultaneously achieve efficient heat dissipation and high load-bearing structural strength.

[0024] 5. In the lower housing of the battery pack of the present invention, the distribution density of the flow channel plate in the region corresponding to the tab of the battery module is greater than that in other regions, forming a flow channel with a width smaller than that in other regions. This region is a high heat flux density region. When the cooling medium passes through this region, the flow velocity increases, the turbulence intensity increases, and the local convective heat transfer coefficient is improved. The distribution density of the flow channel plate in the middle region of the liquid cooling plate is less than that in other regions, forming a flow channel with a width greater than that in other regions. When the cooling medium flows through this region, the flow velocity slows down, reducing unnecessary pressure loss. At the same time, the wide flow channel increases the residence time of the coolant, absorbing residual heat, realizing precise thermal management of the heat source distribution of the battery module, and improving cooling efficiency. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the main structure of the box body in Embodiment 1 of the present invention; Figure 3 This is a partial enlarged view of the ribbed area and planar support area of ​​Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the first metal connector configuration in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the liquid cooling plate assembly structure in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the liquid cooling plate flow channel arrangement in Embodiment 1 of the present invention; Figure 7 This is a top view of the sealing element in Embodiment 1 of the present invention; Figure 8This is a front view of the sealing element in Embodiment 1 of the present invention; Figure 9 This is a flowchart of the method for preparing the main body of the box in Embodiment 2 of the present invention; Among them, 1. Lower housing body, 2. Liquid cooling plate assembly, 3. Sealing components; 101. Side wall of the box; 102. Connection hole; 103. Mesh rib structure; 104. Planar support area; 105. First metal connector; 106. Second metal connector; 107. Opening. 201. Liquid cooling plate, 202. First connecting cavity, 203. Second connecting cavity, 204. Inlet pipe, 205. Outlet pipe.

[0027] 301. Metal frame; 302. Flexible sealing ring. Detailed Implementation

[0028] In this embodiment, the length direction of the lower housing of the battery pack is defined as the first direction, and the width direction is defined as the second direction.

[0029] Example 1 This embodiment provides a battery pack lower housing, such as Figure 1 As shown, it includes a lower housing body 1, which is made of fiber-reinforced thermoplastic resin-based composite material.

[0030] In the lower housing body 1, the surface used to support the battery module is the support surface. The support surface has multiple parallel bearing areas. The length direction of the bearing area is the length direction of the lower housing body. Along the length direction of the lower housing body, the bearing area has multiple spaced grooves, and the grooves have a mesh rib structure.

[0031] This structural form creates multiple alternating planar support areas and mesh rib areas in the load-bearing area. The planar support areas cooperate with the liquid cooling plates of the liquid cooling plate assembly to support the liquid cooling plates.

[0032] The liquid cooling plate assembly 2 is made of metal and is fixedly connected to the lower housing body through metal connectors embedded in the lower housing body.

[0033] Preferably, the liquid cooling plate assembly is made of aluminum alloy.

[0034] In this embodiment, the lower housing body is formed using a compression molding process with fiber-reinforced thermoplastic resin matrix composite material. Under the same strength and stiffness design, compared to a metal lower housing, the weight can be reduced by 30%-50%, significantly improving the energy density and portability of the energy storage system, and reducing transportation and installation costs. Furthermore, the thermoplastic matrix has far superior impact resistance compared to thermosetting materials, making it less prone to invisible delamination or cracking upon impact, resulting in higher safety. Additionally, scrap materials and waste products can be crushed and remelted for reuse, meeting the requirements of a circular economy.

[0035] Fiber-reinforced thermoplastic resin matrix composites contain resin matrix materials and reinforcing fibers. In fiber-reinforced thermoplastic resin matrix composites, the reinforcing fibers are glass fibers, carbon fibers, or basalt fibers. The mass of the reinforcing fibers accounts for 30%-50% of the total mass of the composite material, preferably 40%.

[0036] The type and mass ratio of reinforcing fibers can be set according to actual needs, and will not be described in detail here.

[0037] The resin-based material is either flame-retardant PP or flame-retardant PA material. Existing materials can be used, and will not be described in detail here.

[0038] In this embodiment, as Figure 2 As shown, the lower housing body 1 includes a support box wall, which is used to support the battery module. The support box wall adopts a rectangular structure, and side box walls 101 are provided at its four edges. The top surface of the side box wall 101 is provided with multiple connection holes 102 for connecting the upper cover of the battery pack housing.

[0039] The upper surface of the support box wall serves as a support surface and is provided with multiple support areas. In this embodiment, there are four support areas, which are arranged in parallel and spaced apart.

[0040] like Figure 3 As shown, along the length of the bearing area, i.e., along the first direction, the bearing area has multiple spaced grooves. The grooves are rectangular, and inside the grooves is a mesh rib structure 103 integrally connected to the bearing box wall. The mesh rib structure 103 is integrally molded with the lower box body. Through the arrangement of the mesh rib structure 103, the bearing area has multiple alternating mesh rib areas and planar support areas 104.

[0041] The mesh rib structure 103 includes multiple intersecting first ribs and second ribs, which are integrally connected and also integrally connected to the lower box body.

[0042] The groove is equipped with a mesh rib structure 103, forming a biomimetic skeletal trabecular structure. Compared with the setting of reinforcing ribs, it is more systematic. It can not only transfer concentrated loads (such as the hanging lug force, vibration fatigue, and local collision intrusion) to the entire lower box body through the axial / bending stiffness of the rib plate, avoiding stress concentration in the planar support area, but also effectively improve the low-order natural frequency of the structure and reduce the risk of resonance.

[0043] In this embodiment, the rib height, spacing, or orientation of the mesh rib structure 103 in different grooves are designed differently according to the load of the corresponding area. Based on the load size of different areas of the battery pack (module load-bearing area, connector area, hanging area), the rib height, rib spacing, and rib direction of different mesh rib structures are set to form a stiffness and strength adapted distribution, avoiding redundancy of equal strength design.

[0044] In this embodiment, the alternately arranged planar support area 104 and mesh rib area form a cooperative force-bearing system. The planar support area 104 can provide lateral support for the mesh rib structure 103, suppressing the instability of the mesh rib structure 103. At the same time, the mesh rib structure 103 can provide boundary constraints for the planar support area 104, reducing the flexural deformation of the planar support area 104 under large pressure. The structure of the planar support area 104 plus the mesh rib area can significantly improve the moment of inertia of the lower box body 1. Compared with the pure plane in the load-bearing area of ​​the lower box body 1, the bending stiffness can be greatly improved, significantly improving the load-bearing capacity. Compared with the pure mesh rib structure in the load-bearing area, the stability of the structure is improved, the manufacturing qualification rate is increased, and material waste is reduced.

[0045] The two ends of the bearing box wall along the length direction are pre-embedded with first metal connectors 105, which are used to fix the liquid cooling plate assembly 2.

[0046] The support box wall is also pre-embedded with a number of second metal connectors 106. The second metal connectors 106 are used to fix the battery module. The position of the second metal connectors 106 can be determined according to the battery module, and will not be described in detail here.

[0047] Since the liquid cooling plate assembly is made of metal, it is fixed to the support box wall through the first metal connector 105. Compared with the method of fixing the liquid cooling plate assembly by opening a groove in the liquid cooling plate assembly and allowing the material to flow into the groove during the molding of the lower box body, this method not only utilizes the excellent thermal conductivity of metal materials, but also avoids the stress problems caused by the difference in thermal expansion coefficients between composite materials and metals during long-term thermal cycling.

[0048] like Figures 5-6As shown, the liquid cooling plate assembly 2 includes multiple liquid cooling plates 201, each corresponding to a support area. Since four support areas are provided, four liquid cooling plates 201 are provided. The liquid cooling plates 201 are located above the support areas. The planar support area 104 is in contact with the bottom surface of the liquid cooling plate 201 to support it. One end of the liquid cooling plate 201 is connected to the first connecting cavity 202, and the other end is connected to the second connecting cavity 203.

[0049] The liquid cooling plate 201 is provided with multiple flow channels, which are connected to the internal space of the first connecting cavity 202 and the second connecting cavity 203.

[0050] The first connecting cavity 202 is provided with a partition. Preferably, the partition is located in the middle of the first connecting cavity 202. The partition divides the internal space of the first connecting cavity 202 into a first chamber and a second chamber. The flow channels of the two liquid cooling plates 201 on one side are connected to the first chamber, and the flow channels of the two liquid cooling plates 201 on the other side are connected to the second chamber.

[0051] The first chamber is connected to the inlet pipe 204, which is used to introduce the cooling medium into the first chamber. The second chamber is connected to the outlet pipe 205, which is used to send the cooling medium out of the second chamber.

[0052] After the cooling medium enters the first chamber through the inlet pipe 204, it enters the flow channels in the two liquid cooling plates 201 on one side. After passing through the liquid cooling plates 201, the cooling medium enters the second connecting chamber 203, passes through the second connecting chamber 203, enters the flow channels in the two liquid cooling plates 201 on the other side, and finally exits through the second chamber and the outlet pipe 205, thus completing the flow of the cooling medium.

[0053] By setting up the first connecting cavity 202 and the second connecting cavity 203, not only is the flow of the cooling medium realized, but also multiple liquid cooling plates 201 are connected into a whole. Multiple liquid cooling plates 201 can be installed at the same time without being installed sequentially, which greatly reduces the assembly time of the lower housing and improves the manufacturing efficiency.

[0054] The liquid cooling plate 201, the first connecting cavity 202, and the second connecting cavity 203 are all made of aluminum alloy. The liquid cooling plate 201 includes a base plate and a top cover plate. The top cover plate is fastened to the base plate. Multiple flow channel plates are provided between the top cover plate and the base plate. Cooling medium flow channels are formed between the flow channel plates for the flow of cooling medium. In this embodiment, the multiple flow channel plates are arranged parallel to each other along the first direction. The flow channel plates are arranged perpendicular to the base plate and the top cover plate. A straight cooling medium flow channel is formed between two adjacent flow channel plates. The flow channel adopts a straight shape, which reduces water flow resistance and improves heat dissipation efficiency.

[0055] In this embodiment, the base plate, top cover plate, and flow channel plate are fixed by brazing.

[0056] Meanwhile, the rigidity of the liquid cooling plate is improved by setting multiple flow channel plates. After being connected to the lower housing body 1 by the first metal connector 105, the load-bearing capacity of the battery module is greatly improved. There is no need to add external support beams or significantly increase the plate thickness. This can solve the problem that the liquid cooling plate in the prior art cannot take into account both efficient heat dissipation and high load-bearing structural strength.

[0057] Furthermore, multiple stiffening plates are provided between the flow channel plate and the bottom plate and / or the top cover plate. When the top cover plate is under pressure, the pressure is transmitted to the bottom plate through the stiffening plates and the flow channel plate, thereby preventing the top cover plate from denting and deforming.

[0058] Furthermore, local micro-turbulence structures, such as triangular turbulence pillars, can be arranged inside the first connecting cavity 202 and the second connecting cavity 203. These local micro-turbulence structures can disrupt the boundary layer and further enhance the heat dissipation capacity of the high-heat-generating area.

[0059] like Figure 4 As shown, the first metal connector 105 is embedded in two ends on one side of the bearing box wall. The first metal connector 105 is a metal threaded cylinder. During the molding process of the lower box body, the metal threaded cylinder is directly embedded into the interior of the bearing box wall. Correspondingly, the two ends of the second connecting cavity 203 are provided with fixing holes that match the metal threaded cylinder. The second connecting cavity 203 can be fixedly connected to the metal threaded cylinder through bolts and fixing holes, thereby realizing the fixation between the liquid cooling plate assembly 2 and the lower box body 1.

[0060] Preferably, the bolt is a high-strength bolt with a strength grade of 8.8, 10.9 or 12.9.

[0061] The second metal connector 106 also uses a metal threaded cylinder. During the molding process of the lower housing body, the metal threaded cylinder is directly embedded in the interior of the bearing housing wall. The second metal connector 106 can be fixed to the battery module by bolts.

[0062] In this embodiment, the liquid cooling plate 201 is fixed to the lower housing body 1 by a metal threaded cylinder pre-embedded in the lower housing body 1. Compared with the method of fixing the liquid cooling plate and the lower housing body by slotting the liquid cooling plate 201 and letting the resin material flow into the slot during molding, this method not only utilizes the excellent thermal conductivity of the metal material, but also avoids the stress problem caused by the difference in thermal expansion coefficients between composite materials and metals during long-term thermal cycling. At the same time, the metal threaded cylinder embedded in the lower housing body 1 also plays a role in structural reinforcement of the lower housing body 1, thereby improving the load-bearing capacity of the lower housing body 1.

[0063] Furthermore, the flow channel is configured with varying widths based on the heat generation at different locations within the battery module to address the issue of uneven heat dissipation. Specifically: The distribution density of the flow channel plate in the area corresponding to the battery module's tab is greater than that in other areas. At this time, since the width of the liquid cooling plate 201 is a fixed value, the width of the flow channel formed between adjacent flow channel plates is smaller than the width of the flow channel in the area. This area is a high heat flux density area. When the cooling medium passes through this area, the flow velocity increases, the turbulence intensity increases, and the local convective heat transfer coefficient is improved.

[0064] The distribution density of the flow channel plates in the middle region of the liquid cooling plate 201 is less than that in other regions. At this time, since the width of the liquid cooling plate 201 is a constant, the width of the flow channel between adjacent flow channel plates in this region is greater than that in other regions, forming a low heat flux density region. When the cooling medium flows through this region, the flow rate slows down, reducing unnecessary pressure loss. At the same time, the wide flow channel increases the residence time of the coolant and absorbs residual heat.

[0065] This approach enables precise thermal management of the heat source distribution in the battery module, thereby improving cooling efficiency.

[0066] The inlet pipe 204 and outlet pipe 205 connected to the first connecting cavity 202 pass through the side box wall through the opening 107 provided on the corresponding side box wall 101. Both the inlet pipe 204 and outlet pipe 205 are provided with sealing elements 3 between themselves and the side box wall 101 for sealing.

[0067] In this embodiment, as Figures 7-8 As shown, the seal 3 adopts an existing metal-type sealing ring, including a metal skeleton 301 and a flexible sealing ring 302 wrapped around the metal skeleton.

[0068] Preferably, the metal skeleton 301 is a stainless steel skeleton, and the flexible sealing ring 302 is fluororubber, EPDM, or silicone rubber. Those skilled in the art can choose according to actual needs, and will not be described in detail here.

[0069] In the seal, the metal skeleton 301 provides excellent support rigidity, which can prevent the seal from being compressed and deformed during assembly; the fluororubber has excellent resistance to high and low temperatures and electrolyte corrosion, and combined with the surface pressure advantage of integrated assembly, the sealing performance reaches the IP68 protection level, which is 3-4 times longer than the sealing life of traditional single rubber seal rings, and completely solves the protection pain points such as electrolyte leakage and water vapor intrusion.

[0070] Furthermore, the planar support area 104 can also be bonded and fixed to the bottom surface of the liquid cooling plate 201 by structural adhesive. The planar support area 104 can also provide a large bonding area with the liquid cooling plate 201. While the liquid cooling plate 201 is fixed to the lower housing body 1 by the metal threaded cylinder, it can also be bonded and fixed to the planar support area 104. When the connection between the metal threaded cylinder and the liquid cooling plate 201 becomes loose, the structural adhesive can also ensure the connection strength between the liquid cooling plate 201 and the lower housing body 1. At the same time, since the liquid cooling plate 201 is bonded to the planar support area 104, the rigidity of the lower housing body 1 is increased, further improving the load-bearing capacity of the lower housing body 1.

[0071] Example 2 This embodiment provides a method for preparing the lower casing of the battery pack as described in Embodiment 1. First, the main body 1 of the lower casing is prepared, and then the liquid cooling plate assembly 2 is installed, as follows: Figure 9 As shown, it includes the following steps: After the resin-based material is dried, weigh the set weight of the resin-based material on an electronic scale.

[0072] The resin-based material is heated once to achieve first-stage plasticization. During the first heating, the temperature is set to be 20-30°C higher than the melting point of the resin-based material. Those skilled in the art can set the temperature according to actual needs.

[0073] Reinforcing fibers are introduced into the resin-based material, and secondary heating is performed to achieve secondary plasticization. During secondary heating, the temperature is set to be 40-50°C higher than the melting point of the resin-based material. Those skilled in the art can set the temperature according to actual needs. After the secondary plasticization is completed, a blank is obtained.

[0074] After the blank is cut, it is kept warm and then conveyed into the mold. The mold is preheated and contains a first metal connector and a second metal connector. In this embodiment, the preheating temperature of the first metal connector and the second metal connector is 100-120℃. Those skilled in the art can set it according to actual needs.

[0075] The lower box body is formed by compression molding.

[0076] After the lower housing body is cooled and demolded, the inlet and outlet pipes of the liquid cooling plate assembly are passed through the openings in the side wall, the liquid cooling plate is placed in the corresponding bearing area and mates with the planar support area, and then the second connecting cavity is fixed to the lower housing body with bolts.

[0077] Then, seals are installed between the inlet and outlet pipes and the side box wall, so that one end of the liquid cooling plate assembly is fixed by bolts and the first metal connector, and the other end is fixed by the seals.

[0078] In the manufacturing method of the lower housing in this embodiment, when assembling the liquid cooling plate assembly with the lower housing body, modular assembly is adopted, which is simple and facilitates the realization of automated assembly in the later stage.

[0079] Existing aluminum alloy / steel enclosures require more than 10 processes, including cutting, welding, drilling, corrosion protection, and insulation, with a production cycle of 40-60 minutes per piece. Thermosetting composite material enclosures have a molding cycle of 3-5 minutes per piece, but the material itself has problems such as being non-recyclable, having poor toughness, being prone to micro-cracks after impact, and being unable to be repaired later. The preparation method of this embodiment adopts a molding process, with a molding cycle of only 1.5-2 minutes per piece. During the integrated molding process, the mesh rib structure, grooves, metal connectors and other structures are completed simultaneously, without the need for subsequent machining. Combined with the modular assembly design of the liquid cooling plate, the overall production cycle is shortened by more than 70% compared to the metal box, and the comprehensive production cost of a single set is reduced by 30%-40%, which can fully meet the large-scale mass production demand of the energy storage market with an annual production capacity of more than 100,000 sets.

[0080] Example 3 This embodiment provides a battery pack, which is an energy storage battery pack, and is provided with the lower housing of the battery pack described in Embodiment 1. The remaining structure of the battery pack can be achieved using existing technology, and will not be described in detail here.

[0081] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery pack lower housing, characterized in that, The lower housing body is made of fiber-reinforced thermoplastic resin-based composite material. The support surface of the lower housing body for supporting the battery module is provided with multiple spaced parallel bearing areas. Along the length of the lower housing body, the bearing areas are provided with multiple spaced grooves. The grooves are provided with a mesh rib structure integrally connected to the lower housing body so that the bearing areas have multiple alternating planar support areas and mesh rib areas. It also includes a liquid cooling plate assembly made of metal materials. The liquid cooling plate assembly is fixed to the lower housing body through metal connectors embedded in the lower housing body. The liquid cooling plate assembly includes multiple liquid cooling plates that correspond one-to-one with the load-bearing area. The bottom surface of the liquid cooling plate is attached to the planar support area and supported by the planar support area.

2. The battery pack lower housing as described in claim 1, characterized in that, Multiple liquid cooling plates are connected at one end to a first connecting cavity and at the other end to a second connecting cavity. The first connecting cavity has a partition to divide the space inside the first connecting cavity into a first chamber and a second chamber. The flow channels of some liquid cooling plates are connected to the first chamber, and the flow channels of the remaining liquid cooling plates are connected to the second chamber. The first chamber is connected to an inlet pipe, and the second chamber is connected to an outlet pipe.

3. The battery pack lower housing as described in claim 2, characterized in that, The lower housing body includes a bottom housing wall and side housing walls located at the edge of the bottom housing wall. The top surface of the bottom housing wall serves as a support surface. The inlet pipe and outlet pipe both pass through the corresponding side housing walls and are sealed with seals between them.

4. The battery pack lower housing as described in claim 3, characterized in that, The sealing element includes a metal skeleton, and a flexible sealing ring is wrapped around the outer periphery of the metal skeleton.

5. The battery pack lower housing as described in claim 2, characterized in that, The second connecting cavity is fixedly connected to the lower housing body through a metal connector in the lower housing body.

6. The battery pack lower housing as described in claim 1, characterized in that, The mesh rib structure includes multiple intersecting first ribs and second ribs, which are integrally connected and integrally connected to the lower box body.

7. The battery pack lower housing as described in claim 1, characterized in that, The liquid cooling plate includes a base plate and an upper cover plate, with multiple flow channel plates provided between the base plate and the upper cover plate, and cooling medium flow channels formed between adjacent flow channel plates.

8. The battery pack lower housing as described in claim 7, characterized in that, Multiple flow channel plates are arranged in parallel, and straight cooling medium flow channels are formed between adjacent flow channel plates.

9. The battery pack lower housing as described in claim 7, characterized in that, A stiffening plate is provided between the flow channel plate and the top cover plate and / or the bottom plate.

10. The battery pack lower housing as described in claim 1, characterized in that, In the liquid cooling plate, the distribution density of the flow channel plate in the area corresponding to the battery module's tab is greater than that in the other areas, so that the width of the flow channel is smaller than that in the other areas. The distribution density of the flow channel plate in the middle area of ​​the liquid cooling plate is less than that in the other areas, so that the width of the flow channel is greater than that in the other areas.

11. The battery pack lower housing as described in claim 1, characterized in that, In fiber-reinforced thermoplastic resin-based composites, the reinforcing fibers are glass fibers, carbon fibers, or basalt fibers, and the resin-based material is flame-retardant PP material or flame-retardant PA material.

12. The battery pack lower housing as described in claim 1, characterized in that, The support area is bonded and fixed to the bottom surface of the liquid cooling plate with structural adhesive.

13. A method for preparing the lower casing of a battery pack according to any one of claims 1-12, characterized in that, Includes the following steps: The set weight of resin-based material is heated to the first set temperature once; Reinforcing fibers are added to the resin-based material and then heated a second time to a second set temperature to complete the preparation of the preform; After the blank is cut, the cut blank is sent into a mold pre-inserted with metal connectors. The lower box body is formed by compression molding. After the lower housing body is cooled and demolded, the liquid cooling plate assembly is placed inside the lower housing of the battery pack and fixed to the lower housing body with metal connectors.

14. A battery pack, characterized in that, The battery pack lower housing is provided as described in any one of claims 1-12.

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