Liquid cooling plate and battery pack

Abstract

The invention discloses a liquid cooling plate and a battery pack, and aims to solve the problems of insufficient structural strength, weak bottom protection, low thermal management efficiency, unreliable sealing, high cost and the like of the existing liquid cooling plate. The liquid cooling plate comprises an upper-layer aluminum plate used for being in contact with a battery cell group for heat conduction; the bottom surface of the inner side of the lower-layer box-shaped steel plate is fixedly connected with the upper-layer aluminum plate, a concave-convex structure is arranged on one surface, facing the upper-layer aluminum plate, of the lower-layer box-shaped steel plate, and the concave-convex structure is matched with the bottom surface of the upper-layer aluminum plate to form a closed cooling flow channel; and the bottom foamed aluminum is fixedly connected to the bottom surface of the outer side of the lower-layer box-shaped steel plate and is preferably provided with a profiling structure corresponding to the bottom of the lower-layer box-shaped steel plate. The battery pack provided by the invention adopts the liquid cooling plate, and the lower box-shaped steel plate of the liquid cooling plate is connected with the steel rolling battery frame body and forms reliable sealing with the upper cover of the battery pack through the bolt, the rivet nut and the sealing gasket. Through the three-layer composite structure design, the effects of high structural strength, excellent bottom impact energy absorption protection (an independent bottom protection plate can be omitted), efficient and uniform heat management, reliable sealing and simplified integration are achieved, and the overall performance, safety and economical efficiency of the battery pack are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery packs, and in particular to a liquid cooling plate and a battery pack using the liquid cooling plate. Background Art

[0002] The range, energy density, and overall energy consumption of electric vehicles are key indicators of current technological development. The battery pack's thermal management system, particularly the liquid cooling system, is crucial to battery performance, lifespan, and safety. With the development of highly integrated battery pack technologies like CTP (Cell to Pack), liquid cooling plates must not only provide cooling but also serve as structural components to support the weight of the battery cells and withstand impacts from the vehicle's underside.

[0003] In existing technology, many liquid cooling plates are made of aluminum. Although aluminum has good thermal conductivity, its strength is relatively low. In a CTP structure, when the liquid cooling plate needs to directly support the battery cells, the aluminum liquid cooling plate is easily deformed due to insufficient strength, affecting the close fit between the battery cells and the liquid cooling plate and the thermal efficiency, thereby affecting the performance and safety of the battery cells. In addition, aluminum liquid cooling plates are also less resistant to harsh working conditions such as bottom collisions, gravel impacts, and bottom support. They usually require additional bottom guards, which not only increases the weight and cost of the battery pack, but also makes the structure more complex.

[0004] To address these issues, some proposals have explored the use of composite materials or improved structures. For example, Chinese patent CN222126663U discloses a liquid cooling plate based on a metal composite plate, which consists of an aluminum flat plate and a metal composite flow channel plate, which can be a steel-aluminum composite plate, for example. The disadvantages of this solution are: the molding process of the metal composite plate is complex, the flow channel structure (especially in areas with small local chamfers) is difficult and expensive to process; the difference in thermal expansion coefficients of different metals can lead to delamination; the composite layer is difficult to recycle; and it still fails to effectively solve the bottom protection problem, requiring an additional bottom guard plate.

[0005] Furthermore, Chinese patent CN221041273U discloses a load-bearing liquid cooling plate, which is formed by integrally stamping a steel-aluminum composite plate. The aluminum plate layer is located on the inner side of the steel plate layer and is recessed to form a cooling channel, which is then brazed and sealed by an aluminum sealing plate. This patent aims to reduce leakage points and improve load-bearing capacity through an integrally formed box-type structure liquid cooling plate. However, this solution still has some shortcomings: 1. The forming process of the steel-aluminum composite plate, especially for the box-type structure with complex flow channels and local small chamfers, is still complicated and the cost is relatively high. 2. The thermal expansion coefficients of steel and aluminum are very different, and there is still a risk of delamination under high temperature or repeated hot and cold cycles, which requires high process control. 3. The separation and recovery of the metal composite layer is still difficult. 4. Although its box-type structure enhances the strength of the liquid cooling plate, it may still be necessary to set up an additional bottom guard plate for impact from the bottom, resulting in complex process and increased cost. 5. If the steel plate layer of the box-type structure is connected to a steel box (such as a roll-pressed box), the use of multi-layer spot welding and other methods will result in problems such as complicated process and easy deformation. The spot welding process is not very applicable to the closed roll-pressed steel box frame. At the same time, a large number of sealing welds also bring a higher risk of leakage.

[0006] Therefore, it is urgent to develop a liquid cooling plate and battery pack that has a simple structure, low cost, sufficient strength, reliable sealing, and can effectively cope with bottom impact. Summary of the Invention

[0007] The present invention aims to solve the problems existing in existing liquid cooling plates and battery packs in terms of structural strength, bottom protection, thermal management efficiency, manufacturing cost and sealing reliability. Specifically, the strength of the aluminum liquid cooling plate in the prior art is not enough to meet the load-bearing requirements of the CTP (Cell To Pack) structure for the battery cells, and the ability to resist bottom impact is weak; while some metal composite plate solutions have problems such as complex molding process, high cost, risk of delamination due to differences in thermal expansion of different metals, and the need for additional bottom guard plates. In addition, the connection and sealing of traditional box-type steel liquid cooling plates and battery frames also face challenges such as complicated processes, easy deformation, and many sealing failure points. Therefore, the main purpose of the present invention is to provide a liquid cooling plate with optimized structure, high strength, good thermal conductivity, excellent bottom protection capability, simplified assembly and reliable sealing.

[0008] The present invention provides a liquid cooling plate, comprising an upper aluminum plate for contacting a battery cell group and conducting heat conduction; a lower box-shaped steel plate, wherein the upper aluminum plate is fixedly connected to the inner bottom surface of the lower box-shaped steel plate; and a bottom foam aluminum, wherein the bottom foam aluminum is fixedly connected to the outer bottom surface of the lower box-shaped steel plate; wherein a side of the lower box-shaped steel plate facing the upper aluminum plate is provided with a concave-convex structure, and the concave-convex structure cooperates with the bottom surface of the upper aluminum plate to form a closed cooling channel; and a side of the bottom foam aluminum (preferably a side facing the lower box-shaped steel plate or its exposed bottom surface) is provided with a contoured structure arranged corresponding to the concave-convex structure of the lower box-shaped steel plate.

[0009] As a preferred solution, the contact surfaces of the upper aluminum plate and the lower box-shaped steel plate are connected by at least one of laser welding, explosion welding or brazing.

[0010] As a preferred solution, the concave-convex structure of the lower box-shaped steel plate further includes reinforcing ribs for enhancing the structural strength of the liquid cooling plate.

[0011] As a preferred solution, the cooling channel is a serpentine structure or a multi-channel parallel structure.

[0012] As a preferred solution, the lower box-shaped steel plate is made of galvanized steel plate or stainless steel plate, and / or the surface of the lower box-shaped steel plate is treated for corrosion by coating, electroplating or chemical treatment.

[0013] As a preferred solution, the bottom foam aluminum is connected to the lower box-shaped steel plate by at least one of diffusion welding, laser welding, explosive composite or thermal spraying transition layer.

[0014] The present invention also provides a battery pack, comprising a battery pack upper cover and a lower box body, the lower box body comprising: the liquid cooling plate as described above; a steel roll-rolled battery frame; and a cell group, the cell group being arranged in the steel roll-rolled battery frame and supported on the upper aluminum plate of the liquid cooling plate; wherein the lower box-shaped steel plate of the liquid cooling plate is connected to the steel roll-rolled battery frame, and the liquid cooling plate cooperates with the battery pack upper cover through its lower box-shaped steel plate to form a sealing structure.

[0015] As a preferred solution, the lower box-shaped steel plate of the liquid cooling plate is connected to the upper cover of the battery pack by bolts and rivet nuts, and a sealing gasket is provided between the lower box-shaped steel plate and the upper cover of the battery pack; the rivet nut is provided on the lower box-shaped steel plate or the steel rolled battery frame, and the bolt passes through the upper cover of the battery pack and cooperates with the rivet nut.

[0016] As a preferred solution, it also includes a thermal conductive structural adhesive and an adhesive limiting strip arranged between the battery cell group and the upper aluminum plate.

[0017] As a preferred solution, a glue fixing layer is provided between the lower box-shaped steel plate and the side contact surface of the steel roll-pressed battery frame.

[0018] The beneficial effects of the present invention are: through systematic innovation of the liquid cooling plate and battery pack structure, the present invention successfully integrates the characteristics of high-strength load-bearing, efficient thermal management, excellent bottom protection, reliable sealing and simplified manufacturing, providing a safer, more durable, more efficient and more cost-effective solution for new energy vehicle battery systems.

[0019] First, the present invention discloses a liquid cooling plate core structure. Its three-layer design—an upper aluminum plate for contacting and conducting heat with the battery pack, a lower box-shaped steel plate that serves as the structural framework and forms a closed cooling channel with the upper aluminum plate, and a bottom aluminum foam layer fixed to the outer bottom surface of the lower box-shaped steel plate—offers multiple benefits. The upper aluminum plate ensures efficient heat transfer from the battery cells to the cooling medium, laying the foundation for good thermal management. The lower box-shaped steel plate, with its inherent high strength and rigidity, not only provides solid structural support for the liquid cooling plate, enabling it to effectively bear the weight of the battery pack (especially in a CTP structure) and resist deformation, but also cleverly utilizes its concave-convex structure to form a coolant flow channel together with the upper aluminum plate. Crucially, the introduction of the bottom aluminum foam layer, thanks to the foam material's excellent high damping and shock absorption properties and impact energy absorption, gives the liquid cooling plate excellent underbody protection. It can effectively absorb and disperse energy from collisions, gravel impacts, and other impacts from the vehicle's underbody, thereby replacing the traditional independent underbody guard plate, simplifying the structure, reducing weight, and lowering costs. Furthermore, compared to traditional aluminum sheeting, the thermal conductivity of the lower box-shaped steel sheet is approximately half that of aluminum. The bottom aluminum foam offers excellent thermal insulation, effectively isolating heat and reducing heat exchange between the battery pack and the external environment, helping to maintain stable battery temperature and reduce energy consumption. The contoured structure of the bottom aluminum foam allows it to better conform to the contours of the lower box-shaped steel sheet, further optimizing protection and integration.

[0020] On this basis, the present invention further optimizes the performance and durability of the liquid cooling plate. The upper aluminum plate and the lower box-shaped steel plate are connected by reliable methods such as laser welding, explosion welding or brazing, ensuring a strong mechanical bond and a good heat conduction path between the two.

[0021] Furthermore, the present invention incorporates reinforcing ribs within the concave-convex structure of the lower box-shaped steel plate, further enhancing the overall structural strength and deformation resistance of the liquid cooling plate, ensuring stability under complex operating conditions. Simultaneously, the present invention optimizes the design of cooling channels (such as serpentine or multi-channel parallel structures) to achieve more uniform coolant distribution and more efficient heat exchange, thereby improving overall thermal management performance.

[0022] By selecting galvanized or stainless steel plates or applying surface anti-corrosion treatment, the present invention significantly improves the service life and reliability of the liquid cooling plate in humid, corrosive coolant environments. The connection methods (such as diffusion welding or laser welding) listed in claim 6 (the bottom aluminum foam and the lower box-shaped steel plate) ensure the secure attachment of the aluminum foam protective layer, preventing it from falling off and failing under vibration or impact.

[0023] When the liquid cooling plate of the present invention is applied to the battery pack, its advantages are further demonstrated. The lower box-shaped steel plate of the liquid cooling plate is directly connected to the steel roll-pressed battery frame as part of the lower box body, and cooperates with the battery pack cover to form a sealed structure. This highly integrated design reduces the number of parts and simplifies the assembly process. More importantly, it changes the traditional sealing method and reduces potential leakage points.

[0024] The present invention has this efficient sealing connection method: the liquid cooling plate (the steel plate part) is tightly connected to the battery pack cover by bolts and rivet nuts, and reliable sealing is achieved by relying on sealing gaskets. Compared with large-area welding seals, this mechanical seal not only has a reliable sealing effect, but is also more convenient for subsequent inspection and maintenance.

[0025] Finally, the present invention incorporates thermally conductive structural adhesive and adhesive strips between the battery cell assembly and the upper aluminum plate, ensuring close and uniform thermal contact between the battery cells and the liquid cooling plate, maximizing heat transfer efficiency. The adhesive strips also help control the thickness and range of the adhesive layer. A layer of adhesive fixings, placed between the lower box-shaped steel plate and the side contact surface of the steel roll-formed battery frame, further enhances the overall structural rigidity and connection stability of the battery pack, and may also provide some vibration reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments disclosed in the present invention, the drawings of the embodiments will be briefly introduced below. These drawings are only used for illustrative purposes and are not intended to limit the scope of protection of the present invention.

[0027] Figure 1 This is a schematic exploded view of the overall structure of a liquid cooling plate provided by an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of the top structure of the lower box-shaped steel plate in an embodiment of the present invention.

[0029] Figure 3 For the Figure 2 Schematic diagram of the cross-sectional structure of the liquid cooling plate along the AA line.

[0030] Figure 4 for Figure 3 B is a partial enlarged view of .

[0031] Figure 5A three-dimensional diagram of a steel-aluminum composite liquid cooling plate provided by an embodiment of the present invention.

[0032] Figure 6 An exploded view of a steel-aluminum composite liquid cooling plate, which is a liquid cooling plate provided in an embodiment of the present invention.

[0033] Figure 7 Schematic diagram of the foam aluminum at the bottom of a liquid cooling plate provided in an embodiment of the present invention.

[0034] Explanation of the accompanying numbers: 1-battery pack cover, 2-bolt, 3-battery cell group, 4-thermal conductive structural adhesive, 5-limiting rubber strip, 6-sealing gasket, 7-liquid cooling plate, 71-upper aluminum plate, 72-lower box-shaped steel plate, 721-concave-convex structure, 722-contact surface between lower box-shaped steel plate and side of steel roll-pressed battery frame, 723-contact surface between lower box-shaped steel plate and upper aluminum plate, 73-bottom foam aluminum, 8-rivet nut, 9-steel roll-pressed battery frame, 10-cooling channel. DETAILED DESCRIPTION

[0035] The technical solutions of the present invention (including preferred technical solutions) are further described in detail below by way of accompanying drawings and listing some optional embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Compared with the existing technology that simple aluminum liquid cooling plates are insufficient in strength, or metal composite plates have complex processes and high costs, the key differentiating feature of this embodiment lies in its unique three-layer composite structure and its optimized design. In terms of material selection, aluminum alloys, galvanized steel plates and foamed aluminum materials with a history of extensive application and stable performance in the automotive industry are selected. In terms of connection technology, emphasis is placed on mature and efficient technologies to ensure connection strength and production rhythm. In terms of structural design, the load-bearing capacity of the liquid cooling plate 7 as a structural component is emphasized, and the lower box-shaped steel plate 72 provides the main support, and cooperates with the upper aluminum plate 71 to form an optimized flow channel 10. The application of bottom foamed aluminum 73. The battery pack sealing solution adopts mechanical sealing to improve reliability and ease of maintenance.

[0037] The liquid cooling plate and battery pack described in this embodiment are particularly suitable for mainstream passenger pure electric vehicles that have high requirements for energy density, safety, cycle life and cost control, especially under the design trend of highly integrated battery packs such as CTP (Cell To Pack) or MTP (Module To Pack), which can better play the advantages of their structural and functional integration.

[0038] like Figure 1-7As shown, the liquid cooling plate 7 is the core of this embodiment, which includes a three-layer structure: an upper aluminum plate 71, a lower box-shaped steel plate 72, and a bottom foam aluminum layer 73.

[0039] The upper aluminum plate 71 is in direct contact with the bottom of the battery cell group 3 through the thermal interface material. Its primary function is to efficiently and evenly transfer the heat of the battery cell 3 to the cooling channel 10 formed by the lower steel plate 72 below. The upper aluminum plate 71 can be made of 3003-H14 aluminum alloy with a thickness of 1 to 1.5 mm, taking into account thermal conductivity, formability and cost. The surface roughness Ra of the contact surface between the upper aluminum plate 71 and the battery cell group 3 is controlled at 0.8μm-1.6μm to minimize the interface thermal resistance. The manufacturing process ensures high flatness (≤0.5mm / m), which is crucial for uniform contact of large-area batteries in the CTP structure to avoid hot spots caused by local poor contact.

[0040] The lower box-shaped steel plate 72 is responsible for structural support, flow channel formation, attachment of the bottom foam aluminum 73 to the base, and connection and sealing with the battery pack frame 9 and the upper cover 1. The lower box-shaped steel plate 72 is made of 1.2mm thick hot-dip galvanized low-carbon steel plate to ensure excellent cold formability and corrosion resistance. Its core feature is that a complex concave-convex structure 721 is formed on the side facing the upper aluminum plate 71 through a precision stamping process. The concave-convex structure 721 directly constitutes the flow channel of the coolant, namely the cooling channel 10. Compared with the traditional method of welding or brazing the flow channel plate, this one-piece stamped flow channel design greatly reduces potential leakage points and improves the integrity of the structure. The flow channel design adopts, for example, a serpentine structure or a multi-channel parallel structure. This embodiment is refined into a mixed flow path of "U-shaped parallel + serpentine uniform distribution". Through CFD simulation optimization, it ensures that the temperature uniformity of the entire plate surface (temperature difference is controlled at, for example, ≤5°C) and a lower pressure drop (for example, 15-30kPa) are achieved under the target flow rate (for example, 8-15L / min). The flow channel depth is designed to be 4 to 6mm, and the width is 20mm and 5mm according to the primary and secondary flow channels respectively. Reinforcement ribs are also integrally stamped into the concave-convex structure 721. These reinforcement ribs are cleverly arranged in the flat area or non-flow channel area between the flow channels, which significantly improves the bending and torsional stiffness of the steel plate 72, so that it can better resist the vibration, impact and deformation caused by the load-bearing of the battery pack. This is especially important for the working condition where the liquid cooling plate 7 in the CTP structure directly bears the pressure of the battery cell. In addition to the Z275 galvanized layer, the anti-corrosion measures for the steel plate 72 also include applying a 15μm-25μm thick cathodic electrophoretic coating to the inner and outer surfaces (especially the inner surface of the flow channel) after stamping and completing key connections, further enhancing its resistance to coolant corrosion and external environmental erosion, ensuring the long service life of the liquid cooling plate 7.

[0041] The bottom aluminum foam layer 73 is made of closed-cell or semi-open-cell aluminum foam material with high porosity (e.g., 85%-95%), and its density is controlled at 0.2-0.5 g / cm 3 The thickness is designed according to the ground clearance and protection level requirements of the battery pack, for example, 10mm-20mm. Foam aluminum 73 has excellent energy absorption characteristics. When impacted, its internal pore structure will collapse step by step, thereby absorbing a large amount of impact energy and effectively protecting the core structure of the liquid cooling plate 7 and the battery cell 3 above from damage. The damping performance of foam aluminum is 5-10 times that of metal aluminum. When the foam aluminum with a porosity of 84% is 50% deformed, it can absorb 2.5MJ / m 3 The above energy, these excellent characteristics make the liquid cooling plate 7 in this embodiment do not need to be additionally configured with a traditional steel or composite material bottom guard plate, which significantly simplifies the battery pack structure, reduces weight and reduces costs. The shape of the foam aluminum 73 is not a simple flat plate, but is designed according to the bottom contour of the lower steel plate 72 (including the reverse protrusion of the flow channel pit). It is obtained by molding or CNC processing from a prefabricated block to ensure that it fits tightly with the bottom surface of the steel plate 72, maximizes the contact area, and improves the structural integrity and continuity of the protective cover. In addition, the foam aluminum 73 itself is also a good thermal insulation material (its thermal conductivity is much lower than that of dense aluminum), which can effectively isolate low or high temperatures from the ground or the environment, reduce heat exchange between the battery pack and the outside world, and help maintain the battery cell 3 in a suitable operating temperature range, reducing the energy consumption of the air-conditioning system.

[0042] The connection between the upper aluminum plate 71 and the lower steel plate 72 is achieved using a laser wire-filled brazing process, primarily along the edges 723 of the flow channel "land" (i.e., the flat portion of the uneven structure 721) formed by stamping on the lower steel plate 72. An Al-Si brazing filler metal (such as ER4047) is used. A highly precision-controlled laser beam melts the filler metal and fills the tiny gap (0.1-0.3 mm) between the aluminum and steel plates 71 and 72, forming a continuous, dense weld. This process provides concentrated heat input, minimizes deformation, and effectively controls the thickness of the intermetallic compound (IMC) formation at the interface (target: <5 μm), ensuring sufficient joint strength and good sealing. Prior to welding, the areas to be welded on both the aluminum and steel plates 71 and 72 must undergo rigorous cleaning and surface treatment (deoxidation of the aluminum plate; the steel plate can retain its galvanized coating but weld under specific process controls, or the zinc coating can be partially removed along the weld path and then applied for corrosion protection). The entire welding process is carried out under the protection of inert gas (such as high-purity argon) to prevent oxidation.

[0043] The connection between the bottom foam aluminum 73 and the lower steel plate 72 is mainly carried out by large-area bonding using a high-performance two-component toughened epoxy resin structural adhesive. The foam aluminum and the steel plate can be bonded by gluing, diffusion welding, explosive bonding or hot rolling bonding. In this embodiment, gluing is selected because it has good process adaptability, can evenly disperse stress, fill irregular surfaces, and has certain vibration reduction and sealing auxiliary effects. Before bonding, the bonding surface of the steel plate 72 and the contoured fitting surface of the foam aluminum 73 need to be cleaned, polished and roughened (to enhance the mechanical locking force) and coated with a primer (to improve wettability and increase long-term bonding durability). The thickness of the adhesive layer is controlled to be 0.2-1.0mm, applied by automated equipment, and uniform pressure is applied after assembly, and cured according to the specified temperature and time. This connection method not only ensures the firm combination of the foam aluminum 73 and the steel plate 72, enabling them to synergistically withstand external impacts, but also avoids the stress concentration problem that may be caused by rigid connection.

[0044] The assembly steps of the liquid cooling plate 7 include:

[0045] First, the upper aluminum plate 71 and the lower box-shaped steel plate 72 are respectively manufactured and surface-treated.

[0046] Next, the two components are positioned and clamped using precision tooling and then laser brazed with wire to form an aluminum-steel composite plate structure complete with cooling channels 10. Key quality checks at this stage include weld appearance and dimensions, non-destructive testing (such as ultrasonic testing to verify fusion), and metallographic analysis (spot checks of the IMC layer). Following completion, the channel undergoes an initial airtightness test (for example, maintaining a pressure of 0.2-0.5 MPa for a specified period to check for leaks).

[0047] Next, the surface of the lower steel plate 72 of the "aluminum-steel" composite plate and the surface of the prefabricated bottom foam aluminum 73 are processed before bonding (cleaning, polishing, and applying a primer).

[0048] Then, structural adhesive is evenly applied to the surface of the steel plate 72 or foam aluminum 73, and the two are precisely aligned and pressed to cure. During this stage, the adhesive layer thickness, glue overflow, and curing parameters are checked to ensure they meet the standards.

[0049] Finally, after the glue layer is completely cured, the entire liquid cooling plate 7 assembly is subjected to final dimensional review, visual inspection, and comprehensive air tightness testing (for example, using helium mass spectrometry to detect leaks to ensure that the leakage rate is below the specified limit, such as 1x10^-5Pa·m 3 / s), ensuring that it meets all requirements as a cooling component and a structural component.

[0050] The liquid cooling plate 7 of this embodiment has the advantages of high integration and simplified assembly.

[0051] The battery pack of the present invention mainly consists of a battery pack upper cover 1, a lower box including a liquid cooling plate 7, an internal battery cell group 3 and a steel roll-pressed battery frame 9, etc.

[0052] The lower box-shaped steel plate 72 of the liquid cooling plate 7 is firmly connected to the steel roll-pressed battery frame 9 through the flange structure or specific connection points on its edge, for example, by spot welding, laser welding or bolt connection, forming the main load-bearing structure of the lower box.

[0053] The cell group 3 (which can be a single cell array or a module) is mounted on the upper aluminum plate 71 of the liquid cooling plate 7. To ensure efficient heat conduction and cell positioning, a thermally conductive structural adhesive 4 is evenly applied between the bottom of the cell 3 and the aluminum plate 71. Adhesive limit strips 5 may be used to precisely control the adhesive layer thickness and prevent overflow, ensuring a stable and consistent thermal path.

[0054] The sealing of the battery pack is key. The flange surface on the upper edge of the lower box-shaped steel plate 72 of the liquid cooling plate 7 is sealed with the battery pack cover 1 through a preset sealing gasket 6 (such as EPDM or silicone rubber material, with good compression resilience and durability). The fastening connection between the two adopts a rivet nut 8 and a bolt 2 solution. The rivet nut 8 is pre-installed on the flange of the lower steel plate 72 and the upper edge of the battery frame 9, and the cover 1 is locked with these rivet nuts 8 by bolts 2. The sealing of the battery box is directly ensured by the combination of the liquid cooling plate 7 and the battery pack cover 1. The structure is simple, which avoids the problem of multiple sealing failure points when the spliced ​​frame is used to ensure sealing, and improves the long-term reliability of the seal (IP67 or higher protection level).

[0055] The inlet and outlet nozzles of the coolant are directly integrated or welded to the reserved positions on the upper aluminum plate 71 and are connected to the external cooling pipeline using reliable sealing elements (such as O-rings).

[0056] Furthermore, glue can be added to the contact surface between the lower box-shaped steel plate and the side of the steel rolled battery frame to enhance the structural strength. At the same time, in addition to the mechanical connection, structural glue is also applied to the lateral overlap area between the lower box-shaped steel plate 72 and the battery frame 9 for bonding, thereby further enhancing the torsional stiffness and overall structural strength of the entire lower box.

Claims

1. A liquid cooling plate, characterized in that: It comprises an upper aluminum plate (71) for contacting with the battery cell group (3) and conducting heat conduction, a lower box-shaped steel plate (72) and a bottom foam aluminum (73), wherein the upper aluminum plate (71) is fixed to the inner bottom surface of the lower box-shaped steel plate (72), and the bottom foam aluminum (73) is fixed to the outer bottom surface of the lower box-shaped steel plate (72). The side of the lower box-shaped steel plate (72) facing the upper aluminum plate (71) is provided with a concave-convex structure (721), and the concave-convex structure (721) cooperates with the bottom surface of the upper aluminum plate (71) to form a closed cooling channel (10); the side of the bottom foam aluminum (73) facing the bottom foam aluminum (73) is provided with a contoured structure arranged corresponding to the concave-convex structure (721).

2. The liquid cooling plate according to claim 1, wherein: The contact surfaces (723) of the upper aluminum plate (71) and the lower box-shaped steel plate (72) are connected by at least one of laser welding, explosion welding or brazing.

3. The liquid cooling plate according to claim 1, wherein: The concave-convex structure (721) of the lower box-shaped steel plate (72) further comprises reinforcing ribs for enhancing the structural strength of the liquid cooling plate.

4. The liquid cooling plate according to claim 1, wherein: The cooling channel (10) is a serpentine structure or a multi-channel parallel structure.

5. The liquid cooling plate according to claim 1, wherein: The lower box-shaped steel plate (72) is made of a galvanized steel plate or a stainless steel plate, and the surface of the lower box-shaped steel plate (72) is subjected to anti-corrosion treatment by coating, electroplating or chemical treatment.

6. The liquid cooling plate according to claim 1, wherein: The bottom foam aluminum (73) is connected to the lower box-shaped steel plate (72) by at least one of diffusion welding, laser welding, explosive compounding or thermal spraying transition layer.

7. A battery pack, characterized in that: The invention comprises a battery pack upper cover (1) and a lower box body, wherein the lower box body comprises a liquid cooling plate (7) as described in any one of claims 1 to 6, a steel roll-pressed battery frame (9) and a battery cell group (3), wherein the battery cell group (3) is arranged in the steel roll-pressed battery frame (9) and supported on the upper aluminum plate (71) of the liquid cooling plate (7); the lower box-shaped steel plate (72) of the liquid cooling plate (7) is connected to the steel roll-pressed battery frame (9), and the liquid cooling plate (7) cooperates with the battery pack upper cover (1) through its lower box-shaped steel plate (72) to form a sealing structure.

8. The battery pack according to claim 7, characterized in that: The lower box-shaped steel plate (72) of the liquid cooling plate (7) is connected to the battery pack upper cover (1) via bolts (2) and rivet nuts (8), and a sealing gasket (6) is provided between the lower box-shaped steel plate (72) and the battery pack upper cover (1); the rivet nut (8) is provided on the lower box-shaped steel plate (72) or the steel rolled battery frame (9), and the bolt (2) passes through the battery pack upper cover (1) and cooperates with the rivet nut (8).

9. The battery pack according to claim 7, characterized in that: It also includes a heat-conducting structural adhesive (4) and an adhesive limiting strip (5) arranged between the battery cell group (3) and the upper aluminum plate (71).

10. The battery pack according to claim 7, characterized in that: A glue fixing layer is provided between the lower box-shaped steel plate (72) and the side contact surface (722) of the steel roll-pressed battery frame (9).

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