Composite battery pack thermal management system and thermal management method

Abstract

The invention provides a composite battery pack thermal management system and a thermal management method, and relates to the technical field of battery thermal management, the composite battery pack thermal management system comprises a battery pack box body, the battery pack box body is provided with a mounting cavity with a top opening, the mounting cavity is filled with a liquid cooling medium, and the side wall of the bottom of the battery pack box body is provided with a liquid outlet communicated with the mounting cavity; the plurality of single battery cells are fixedly arranged in the mounting cavity and are immersed in the liquid cooling medium; the three-period extremely-small curved surface structure is arranged in the mounting cavity and surrounds the outer side of the single battery core; the phase-change material is arranged in the pores of the three-period extremely-small curved surface structure; the liquid cooling box is fixedly arranged at the opening in the top of the battery pack box body and is communicated with the mounting cavity, and a liquid inlet is formed in the liquid cooling box. The phase change material disclosed by the invention is combined with a three-period minimum curved surface structure, so that the heat dissipation efficiency of the battery can be improved, a cooling strategy is dynamically adjusted under different temperature conditions, efficient heat dissipation is ensured, the overall reliability and flexibility of a system are improved, and different working environments and requirements are adapted.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and in particular to a composite battery pack thermal management system and a thermal management method. Background Art

[0002] With the development of new energy vehicles, power batteries, as core components, bear the key tasks of providing power and storing energy. Under the conditions of high energy density and high power output, power batteries will generate a lot of heat during the charging and discharging process. Excessive temperature will not only affect the cycle life of the battery, but may also cause thermal runaway and bring safety hazards. Therefore, an efficient and uniform thermal management system is the key to ensuring the safe and stable operation of the battery pack.

[0003] At present, the most widely used power battery heat dissipation methods include liquid cooling and phase change material cooling. The large specific heat capacity of the coolant can quickly absorb and take away the heat generated by the power battery during operation, allowing the battery module to quickly dissipate heat at high temperatures. Liquid cooling has been widely used in the field of power battery heat dissipation. However, due to the heating of the battery module, the temperature of the cooling fluid gradually increases in the flow direction, and a temperature gradient problem will occur, resulting in a large temperature difference inside the power battery pack, which seriously affects the performance and life of the power battery.

[0004] Phase change material cooling technology uses the property of materials to absorb or release a large amount of latent heat during the phase change process to maintain temperature stability. In battery thermal management, phase change materials can absorb heat when the battery temperature is too high to relieve the pressure of rising temperature. However, the heat absorption capacity of phase change materials depends on their phase change process. When the phase change material changes from solid to liquid, it can absorb a certain amount of heat, but once the phase change material is completely melted, it can no longer absorb heat, causing the cooling effect to gradually fail. If the battery continues to work, the temperature will rise rapidly and there is a risk of thermal runaway. In addition, the heat dissipation effect of phase change materials depends to a large extent on their contact area, and most existing phase change material heat dissipation structures cannot provide sufficient heat dissipation area, resulting in low heat dissipation efficiency, especially under long-term high-power output conditions, the cooling effect is difficult to maintain.

[0005] Although existing liquid cooling and phase change material cooling technologies have their own advantages and disadvantages, it is difficult for them to meet the thermal management requirements of battery packs under various working conditions. Especially under extreme working conditions such as high-power discharge and fast charging, a single cooling method cannot effectively balance cooling efficiency and temperature uniformity. Summary of the invention

[0006] In view of this, the present invention proposes a composite battery pack thermal management system and thermal management method, which can ensure efficient heat dissipation under different working conditions, and can also ensure the uniformity of the internal temperature of the battery pack, reduce the impact of temperature difference on battery performance, reduce the risk of thermal runaway, and improve the safety and service life of the battery pack.

[0007] The technical solution of the present invention is achieved in this way:

[0008] In one aspect, the present invention provides a composite battery pack thermal management system, comprising:

[0009] A battery pack box body, which has a mounting cavity with a top opening, the mounting cavity is filled with a liquid cooling medium, and a liquid outlet connected to the mounting cavity is opened on the bottom side wall of the battery pack box body;

[0010] A plurality of single cells are fixedly arranged in the mounting cavity and immersed in the liquid cooling medium;

[0011] A three-period minimal curved surface structure is arranged in the mounting cavity and surrounds the outside of the single cell;

[0012] Phase change material, arranged in the pores of the three-periodic minimal surface structure;

[0013] A liquid cooling box is fixedly arranged at the top opening of the battery pack body and communicated with the installation cavity, and a liquid inlet is provided on the liquid cooling box;

[0014] The control device includes a first temperature sensor, a second temperature sensor, an electromagnetic flow valve and a controller. The first temperature sensor is arranged on a single cell and is used to detect the temperature of the single cell. The second temperature sensor is used to detect the temperature of the phase change material. The electromagnetic flow valve is respectively arranged at the liquid inlet and the liquid outlet. The first temperature sensor, the second temperature sensor and the electromagnetic flow valve are respectively electrically connected to the controller. The controller controls the opening and closing of the electromagnetic flow valve and the flow of the liquid cooling medium according to the acquired temperature data.

[0015] On the basis of the above technical solution, preferably, an upper partition and a lower partition are fixedly arranged in the installation cavity, and the upper partition and the lower partition divide the installation cavity into an upper chamber and a lower chamber independent of each other, and a plurality of installation sleeves are vertically fixedly arranged between the upper partition and the lower partition, and the single battery cells are vertically fixedly arranged in the installation sleeves, and a coolant channel is provided between the single battery cells and the installation sleeves, and the coolant channel is connected with the liquid cooling box and the lower chamber, and the liquid outlet is connected with the lower chamber, and the three-period minimal surface structure is arranged in the upper chamber.

[0016] On the basis of the above technical solution, preferably, a spiral flow channel fixedly connected to the inner wall of the mounting sleeve is provided in the coolant channel.

[0017] On the basis of the above technical solution, preferably, a plurality of first through holes are opened on the side wall of the mounting sleeve, a plurality of second through holes are opened on the lower partition, the upper chamber and the coolant channel are connected through the first through holes, the upper chamber and the lower chamber are connected through the second through holes, and a coating layer wrapping a phase change material is also provided in the pores of the three-periodic minimal surface structure, and the coating layer is a high thermal conductivity polymer or a composite material.

[0018] On the basis of the above technical solution, preferably, a plurality of single battery cells are arranged to form a plurality of battery cell groups, a plurality of mutually independent shunt chambers are arranged inside the liquid cooling box, each shunt chamber corresponds to a battery cell group, a plurality of liquid through ports are arranged at the bottom of the shunt chamber, and the plurality of liquid through ports correspond one by one to the plurality of single battery cells in the battery cell group.

[0019] On the basis of the above technical solution, preferably, a guide plate with a circular structure is fixedly provided in the liquid through port, an annular channel is provided between the guide plate and the liquid through port, and the annular channel corresponds to the coolant channel.

[0020] On the basis of the above technical solution, preferably, the bottom surface of the liquid cooling box and the top surface of the upper partition are connected.

[0021] On the basis of the above technical solution, preferably, a space is provided between the bottom surface of the liquid cooling box and the upper partition, and a plurality of third through holes communicating with the upper chamber are provided on the upper partition.

[0022] On the basis of the above technical solution, preferably, the three-periodic minimal surface structure is any one of a Gyroid surface structure, a Primitive surface structure, a Diamond surface structure and an I-WP surface structure.

[0023] In a second aspect, the present invention discloses a composite battery pack thermal management method, which utilizes the composite battery pack thermal management system described in the first aspect, and includes the following steps:

[0024] S1. When the temperature of the single cell is lower than 40°C and the temperature of the phase change material is lower than 33°C, the coolant in the battery pack is in a static state, and the static coolant and the phase change material work together to achieve heat dissipation of the single cell;

[0025] S2. When the temperature of the single cell is higher than 40°C and the temperature of the phase change material is greater than 33°C and lower than 35°C, coolant is circulated into the battery pack at a low flow rate. The coolant flows through the surface of the single cell to take away the heat. At the same time, the phase change medium absorbs the heat in the coolant, assisting the thermal management system to achieve active and passive synchronous heat dissipation;

[0026] S3. When the temperature of the single cell is higher than 40°C and the temperature of the phase change material is greater than 35°C, the phase change material is completely melted and the coolant is circulated into the battery pack at a high flow rate. The cooling method of the battery thermal management system is converted to active immersion dynamic cooling.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention achieves the following technical effects by combining static cooling, low-flow dynamic cooling, high-flow dynamic cooling and multi-level thermal management of phase change materials: 1. Dynamically adjust the cooling strategy under different temperature conditions to ensure efficient heat dissipation. 2. The use of phase change materials combined with three-period minimal surface structure improves the heat dissipation efficiency of the single cell temperature inside the battery pack, makes the heat dissipation more uniform, and avoids local overheating. 3. Select the appropriate cooling mode as needed to avoid unnecessary energy consumption, especially through static cooling and passive heat dissipation of phase change materials under low temperature conditions to save energy. 4. The combination of multiple cooling methods improves the overall reliability and flexibility of the system and adapts to different working environments and needs.

[0029] (2) By setting the upper partition, the lower partition and the installation sleeve, on the one hand, they are used to fix the single battery cell in the installation cavity. By fixing the single battery cell in the installation sleeve and filling the liquid cooling medium in the cooling liquid channel, the single battery cell can be immersed in cooling. Since each single battery cell is respectively arranged in the installation sleeve, the cooling liquid channel provides an independent cooling space for the single battery cell, ensuring that the liquid cooling medium in each space dissipates heat for the single battery cell separately, making the temperature distribution in each space more uniform, thereby ensuring that all single battery cells have higher temperature uniformity; on the other hand, the setting of the upper partition, the lower partition and the installation sleeve divides the installation cavity into an upper chamber. The upper chamber is a closed space, which provides a three-period minimal surface structure and a storage space for phase change materials. Therefore, the liquid cooling medium will not enter the upper chamber, preventing the phase change material from melting and flowing away with the liquid cooling medium.

[0030] (3) With the setting of the spiral flow channel, when the liquid cooling medium in the battery pack box is in a circulating flow, the liquid cooling medium passes through the spiral flow channel from top to bottom, which can increase the contact time between the liquid cooling medium and the single battery cell and improve the cooling efficiency. In addition, the setting of the spiral flow channel can, on the one hand, fix the single battery cell in the mounting sleeve to ensure the structural stability of the single battery cell. On the other hand, the spiral flow channel is a spiral plate body, which is in contact with the inner wall of the mounting sleeve and the outer wall of the single battery cell respectively, so that the heat released by the single battery cell can be quickly transferred to the mounting sleeve through the spiral flow channel, and then quickly transferred to the phase change material by the three-period minimal surface structure, thereby improving the phase change heat absorption efficiency of the phase change material.

[0031] (4) By setting a first through hole on the mounting sleeve and a second through hole on the lower partition, the liquid cooling medium can be directly in contact with the phase change material, and the heat exchange between the phase change material and the liquid cooling medium is more direct and efficient. The heat exchange area is larger, and the liquid cooling medium can transfer heat to the phase change material more quickly, accelerating its phase change process from solid to liquid. At the same time, the heat transfer path from the single battery cell to the phase change material is shortened, so that the phase change material can absorb heat more quickly and achieve phase change conversion.

[0032] (5) The phase change material is encapsulated in the coating layer to form a phase change microcapsule structure. When the phase change material changes from solid to liquid, the coating layer can effectively prevent it from flowing out, thereby preventing it from mixing into the liquid cooling medium after melting and flowing away, thereby ensuring the integrity of the phase change material and the stability of the system.

[0033] (6) A circular guide plate is fixedly arranged in the liquid passage, and an annular channel is provided between the guide plate and the liquid passage, and the annular channel corresponds to the coolant channel. In this arrangement, most of the liquid cooling medium in the diversion cavity flows out through the annular channel and enters the coolant channel, and the liquid cooling medium flows downward along the coolant channel, which can reduce the direct impact of the liquid cooling medium on the top surface of the single cell, and avoid physical damage to the single cell caused by long-term high flow impact.

[0034] (7) By setting a gap between the bottom surface of the liquid cooling box and the upper partition, a plurality of third through holes connected to the upper chamber are opened on the upper partition. Therefore, the liquid cooling medium flowing out of the annular channel will fill the space between the upper partition and the liquid cooling box. This part of the liquid cooling medium is in a flowing low-temperature coolant, and when these liquid cooling media flow, a part of them quickly passes through the coolant channel to achieve heat exchange with the single battery cell, and the other part passes through the third through hole into the upper chamber to achieve the conversion of the phase change material from liquid to solid, so that the phase change material can be quickly recovered, and then repeatedly exert its heat absorption effect, thereby improving the heat dissipation efficiency of the single battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 It is a schematic diagram of the overall structure of the composite battery pack thermal management system disclosed in the present invention;

[0037] Figure 2 A schematic diagram of the internal structure of the composite battery pack thermal management system disclosed in the present invention;

[0038] Figure 3 A longitudinal cross-sectional view of the composite battery pack thermal management system disclosed in the present invention;

[0039] Figure 4 It is a schematic diagram of the assembly of a single cell, a mounting sleeve and a three-periodic minimal surface structure disclosed in the present invention;

[0040] Figure 5 It is a schematic diagram of the assembly structure of the single cell and the spiral flow channel disclosed in the present invention;

[0041] Figure 6 It is a transverse cross-sectional view of the composite battery pack thermal management system disclosed in the present invention;

[0042] Figure 7 It is a schematic diagram of the bottom structure of the battery pack box disclosed in the present invention;

[0043] Figure 8 It is a schematic diagram of the assembly structure of the battery pack box and the liquid cooling box disclosed in the present invention;

[0044] Reference numerals:

[0045] 1. Battery pack body; 10. Installation cavity; 11. Liquid outlet; 2. Cell group; 20. Single cell; 3. Three-period minimal surface structure; 4. Phase change material; 5. Liquid cooling box; 50. Liquid inlet; 12. Upper partition; 13. Lower partition; 101. Upper chamber; 102. Lower chamber; 6. Installation sleeve; 61. Cooling liquid channel; 62. Spiral flow channel; 63. First through hole; 131. Second through hole; 51. Diverter cavity; 511. Liquid outlet; 121. Third through hole; 52. Guide plate; 521. Annular channel. DETAILED DESCRIPTION

[0046] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] like Figure 1 As shown, combined Figure 2 and 3 The embodiment of the present invention discloses a composite battery pack thermal management system, including a battery pack box 1, a plurality of single cells 20, a three-period minimal surface structure 3, a phase change material 4, a liquid cooling box 5 and a control device.

[0048] The battery pack case 1 has a mounting cavity 10 with an opening at the top, and the mounting cavity 10 is used to accommodate a plurality of single cells 20. The mounting cavity 10 is filled with a liquid cooling medium, which is a coolant made of insulating material, and is used to immerse the single cells 20. A liquid outlet 11 connected to the mounting cavity 10 is provided on the bottom side wall of the battery pack case 1 to ensure that the liquid cooling medium can flow and take away heat.

[0049] A plurality of single cells 20 are fixedly mounted in the mounting cavity 10 and immersed in a liquid cooling medium. The liquid cooling medium acts as a heat exchange medium in the mounting cavity 10. When the battery is working, the liquid cooling medium effectively absorbs and takes away the heat generated by the battery.

[0050] The three-periodic minimal surface structure 3 is arranged in the installation cavity 10 and surrounds the outside of the single battery cell 20, and the phase change material 4 is arranged in the pores of the three-periodic minimal surface structure 3. Among them, the three-periodic minimal surface structure 3 has an extremely high surface area to volume ratio. Due to its periodic and microstructural characteristics, the three-periodic minimal surface structure 3 can provide a large amount of surface area, which significantly enhances the heat conduction path. Its high surface area ensures that the heat can be quickly conducted from the battery cell to the entire three-periodic minimal surface structure 3, and is embedded in the pores of the three-periodic minimal surface structure 3 through the phase change material 4, which significantly increases the contact area between the phase change material 4 and the heat source, and accelerates the heat absorption process of the phase change material 4.

[0051] The pores of the three-period minimal surface structure 3 not only provide a larger surface area, but also optimize the distribution of the phase change material 4, so that heat can be evenly transferred to the phase change material 4, reducing the formation of local hot spots. The phase change material 4 helps to smooth the heat conduction process and avoid local runaway due to overheating by absorbing the heat transferred by the three-period minimal surface structure 3. The phase change material 4 quickly absorbs heat and alleviates overheating through its phase change characteristics, while the three-period minimal surface structure 3 ensures rapid heat transfer. The synergistic effect of the two can greatly improve the heat dissipation efficiency of the battery pack under different working conditions and reduce the risk of thermal runaway.

[0052] In this embodiment, the three-periodic minimal surface structure 3 is any one of a Gyroid surface structure, a Primitive surface structure, a Diamond surface structure and an I-WP surface structure.

[0053] The liquid cooling box 5 is fixedly arranged at the top opening of the battery pack case 1 and communicated with the installation cavity 10. A liquid inlet 50 is provided on the liquid cooling box 5. Liquid cooling medium can be introduced into the liquid cooling box 5 through the liquid inlet 50. The liquid inlet 50 and the liquid outlet 11 cooperate with each other to realize the circulation of the liquid cooling medium in the battery pack case 1, thereby driving the heat released by the single battery cell 20. In this embodiment, when the liquid inlet 50 and the liquid outlet 11 are all closed, the liquid cooling medium is in a static state in the battery pack case 1. When the liquid inlet 50 and the liquid outlet 11 are opened, the liquid cooling medium can circulate through the inside of the battery pack case 1.

[0054] The control device includes a first temperature sensor, a second temperature sensor, an electromagnetic flow valve and a controller (not shown in the figure), wherein the first temperature sensor is arranged on the single cell 20 to detect the temperature of the single cell 20, the second temperature sensor is used to detect the temperature of the phase change material 4, and the electromagnetic flow valve is respectively arranged at the liquid inlet 50 and the liquid outlet 11, the first temperature sensor, the second temperature sensor, and the electromagnetic flow valve are respectively electrically connected to the controller, and the controller controls the opening and closing of the electromagnetic flow valve and the flow rate of the liquid cooling medium according to the acquired temperature data.

[0055] When the temperature of the single cell 20 is lower than 40°C, the temperature of the phase change material 4 is lower than 33°C, the system adopts static immersion cooling, the electromagnetic flow valve is closed, and the cooling medium does not flow in the battery pack box 1. At this time, the heat is mainly dissipated through the synergistic effect of the static coolant and the phase change material 4. The phase change material 4 absorbs heat and undergoes phase change, balances the temperature, improves temperature balance, and does not consume additional energy.

[0056] When the temperature of the single cell 20 is higher than 40°C and the temperature of the phase change material 4 is greater than 33°C and lower than 35°C, the controller controls the electromagnetic flow valve to open slightly, and the cooling medium circulates at a low flow rate. The cooling medium flows through the surface of the single cell 20 to take away some heat, and the phase change material 4 continues to absorb heat to provide auxiliary heat dissipation. In this mode, the system achieves active and passive synchronous heat dissipation to maintain battery temperature balance.

[0057] When the coolant temperature is higher than 40°C and the phase change material 4 temperature is higher than 35°C, the phase change material 4 is basically completely melted, and the controller controls the electromagnetic flow valve to fully open, the coolant circulates at a high flow rate, and the system is converted to active cooling mode. At this time, the rapid circulation of high-flow coolant effectively removes a large amount of heat to prevent the battery from overheating.

[0058] The present invention achieves the following technical effects by combining static cooling, low-flow dynamic cooling, high-flow dynamic cooling and multi-level thermal management of phase change materials 4: 1. Dynamically adjust the cooling strategy under different temperature conditions to ensure efficient heat dissipation. 2. The use of phase change material 4 combined with the three-period minimal surface structure 3 improves the temperature heat dissipation efficiency of the single cell 20 inside the battery pack, and the heat dissipation is more uniform, avoiding local overheating. 3. Select the appropriate cooling mode as needed to avoid unnecessary energy consumption, especially through static cooling and passive heat dissipation of phase change materials under low temperature conditions to save energy. 4. The combination of multiple cooling methods improves the overall reliability and flexibility of the system and adapts to different working environments and needs.

[0059] The present invention further optimizes the thermal management system of the composite battery pack and also provides the following technical solutions.

[0060] See attached Figure 3 and 7 As shown, an upper partition 12 and a lower partition 13 are fixedly arranged in the installation cavity 10, and the upper partition 12 and the lower partition 13 divide the installation cavity 10 into an upper chamber 101 and a lower chamber 102 that are independent of each other. A plurality of installation sleeves 6 are vertically fixedly arranged between the upper partition 12 and the lower partition 13. The single cell 20 is vertically fixedly arranged in the installation sleeve 6. A coolant channel 61 is provided between the single cell 20 and the installation sleeve 6. The coolant channel 61 is connected to the liquid cooling box 5 and the lower chamber 102, and the liquid outlet 11 is connected to the lower chamber 102. The three-periodic minimal surface structure 3 is arranged in the upper chamber 101 and is fixedly connected to the outer wall of the installation sleeve 6.

[0061] By setting the upper partition 12, the lower partition 13 and the installation sleeve 6, on the one hand, they are used to fix the single battery cell 20 in the installation cavity 10, and by fixing the single battery cell 20 in the installation sleeve 6 and filling the liquid cooling medium in the cooling liquid channel 61, immersion cooling of the single battery cell 20 can be achieved. Since each single battery cell 20 is respectively arranged in the installation sleeve 6, the cooling liquid channel 61 provides an independent cooling space for the single battery cell 20, ensuring that the liquid cooling medium in each space dissipates heat for the single battery cell 20 separately, making the temperature distribution in each space more uniform, thereby ensuring that all the single battery cells 20 have a higher temperature uniformity.

[0062] On the other hand, the upper partition 12, the lower partition 13 and the installation sleeve 6 are arranged to divide the installation cavity 10 into an upper chamber 101. The upper chamber 101 is a closed space, which provides a storage space for the three-periodic minimal surface structure 3 and the phase change material 4. Therefore, the liquid cooling medium will not enter the upper chamber 101, so as to prevent the phase change material 4 from melting and flowing away with the liquid cooling medium.

[0063] Under static immersion liquid cooling conditions, the liquid cooling medium filled in the cooling liquid channel 61 absorbs the heat released by the single battery cell 20. At the same time, the heat absorbed by the liquid cooling medium will be transferred to the mounting sleeve 6. The phase change material 4 in the upper chamber 101 absorbs the heat in the mounting sleeve 6 with the cooperation of the three-period minimal surface structure 3, thereby achieving auxiliary heat dissipation for the single battery cell 20 and providing stable temperature control.

[0064] When in dynamic immersion liquid cooling condition, the liquid cooling medium is introduced through the liquid cooling box 5, and then flows downward through the cooling liquid channel 61. During the flow of the liquid cooling medium, the heat released by the single battery cell 20 is driven and enters the lower chamber 102, and finally discharged from the liquid outlet 11. At the same time, when the liquid cooling medium passes through the cooling liquid channel 61, the heat in the phase change material 4 can be absorbed by the installation sleeve 6 and the three-period minimal surface structure 3, and the molten phase change material 4 can be converted into a solid, thereby providing continuous thermal management performance for the single battery cell 20 in the future.

[0065] As some preferred implementations, refer to the attached Figure 3-6 As shown, a spiral flow channel 62 fixedly connected to the inner wall of the mounting sleeve 6 is provided in the cooling liquid channel 61. Thus, under the setting of the spiral flow channel 62, when the liquid cooling medium in the battery pack box 1 is in a circulating flow, the liquid cooling medium passes through the spiral flow channel 62 from top to bottom, which can increase the contact time between the liquid cooling medium and the single battery cell 20 and improve the cooling efficiency.

[0066] In addition, the setting of the spiral flow channel 62 can, on the one hand, fix the single battery cell 20 in the installation sleeve 6 to ensure the structural stability of the single battery cell 20. On the other hand, the spiral flow channel 62 is a spiral plate body, which is in contact with the inner wall of the installation sleeve 6 and the outer wall of the single battery cell 20 respectively. The heat released by the single battery cell 20 can be quickly transferred to the installation sleeve 6 through the spiral flow channel 62, and quickly transferred to the phase change material 4 by the three-period minimal surface structure 3, thereby improving the phase change heat absorption efficiency of the phase change material 4.

[0067] In the above embodiment, the phase change material 4 is filled in the pores of the three-period minimal surface structure 3. Although the phase change material 4 and the three-period minimal surface are located in the upper chamber 101 as a whole, the phase change material 4 absorbs the heat transferred by the three-period minimal surface structure 3 and then undergoes a phase change process to achieve control of the internal temperature of the battery pack body 1. However, the three-period minimal surface is in contact with the mounting sleeve 6. The heat released by the single cell 20 is first transferred to the liquid cooling medium, and the liquid cooling medium transfers the heat to the mounting sleeve 6, which is then absorbed by the three-period minimal surface and transferred to the phase change material 4. This heat transfer path is large and the efficiency is low, especially when the phase change is from liquid to solid, and the time required is also long.

[0068] To this end, the present invention also adopts the following technical solution to solve the problem.

[0069] For details, please refer to the attached Figure 4 and 7 As shown, a plurality of first through holes 63 are provided on the side wall of the mounting sleeve 6, a plurality of second through holes 131 are provided on the lower partition plate 13, the upper chamber 101 and the coolant channel 61 are connected through the first through holes 63, the upper chamber 101 and the lower chamber 102 are connected through the second through holes 131, and a coating layer wrapping the phase change material 4 is also provided in the pores of the three-periodic minimal surface structure 3, and the coating layer is a high thermal conductivity polymer or a composite material.

[0070] According to this arrangement, when in dynamic immersion liquid cooling, the liquid cooling medium inside the battery pack box 1 can enter the upper chamber 101 through the first through hole 63 and the second through hole 131, so that the liquid cooling medium is in direct contact with the phase change material 4, and the heat exchange between the phase change material 4 and the liquid cooling medium is more direct and efficient, the heat exchange area is larger, and the liquid cooling medium can transfer heat to the phase change material 4 more quickly, accelerating its phase change process from solid to liquid. At the same time, the heat transfer path from the single battery cell 20 to the phase change material 4 is shortened, so that the phase change material 4 can absorb heat more quickly and realize phase change conversion.

[0071] When in dynamic immersion liquid cooling and the liquid-cooling medium flows at a low flow rate, when the liquid-cooling medium flows downward from the cooling liquid channel 61, a part of the liquid-cooling medium will flow along the cooling liquid channel 61 toward the lower chamber 102, and a part of the liquid-cooling medium will enter the upper chamber 101 through the first through hole 63. This part of the liquid-cooling medium will contact the phase change material 4 and undergo a phase change transformation. At this time, the phase change material 4 coexists in two states, namely, absorbing heat and releasing heat, so that the phase change material 4 can maintain a continuous phase change transformation and provide lasting temperature control. The liquid-cooling medium that undergoes heat exchange can quickly enter the lower chamber 102 from the second through hole 131, thereby realizing the circulation of the liquid-cooling medium.

[0072] When the liquid cooling medium flows at a high flow rate, the phase change material 4 has completely melted, and the liquid cooling medium entering the upper chamber 101 is in contact with the phase change material 4, which can effectively realize the phase change material 4 from liquid to solid, and subsequently provide continuous thermal management performance for the single battery cell 20. At the same time, when the high flow rate of liquid cooling medium flows through the cooling liquid channel 61, it can quickly take away the heat released by the single battery cell 20, and realize efficient heat dissipation of the single battery cell 20.

[0073] Since the liquid-cooling medium needs to contact the phase-change material 4 when entering the upper chamber 101, the phase-change material 4 will flow out from the pores of the three-period minimal surface structure 3 after melting, and flow away with the liquid-cooling medium. Therefore, in this embodiment, the phase-change material 4 is encapsulated in the coating layer to form a phase-change microcapsule structure. When the phase-change material 4 changes from solid to liquid, the coating layer can effectively prevent it from flowing out, and further prevent it from mixing into the liquid-cooling medium after melting and flowing away, thereby ensuring the integrity of the phase-change material 4 and the stability of the system.

[0074] As some preferred implementations, refer to the attached Figure 3 and 8 As shown, a plurality of single battery cells 20 are arranged to form a plurality of battery cell groups 2, a plurality of mutually independent diversion chambers 51 are arranged inside the liquid cooling box 5, each diversion chamber 51 corresponds to a battery cell group 2, a plurality of liquid through ports 511 are arranged at the bottom of the diversion chamber 51, and the plurality of liquid through ports 511 correspond one by one to the plurality of single battery cells 20 in the battery cell group 2.

[0075] By adopting the above technical solution, each diversion cavity 51 corresponds to a battery cell group 2, and the liquid cooling medium can flow directly downward from the liquid cooling box to each single battery cell 20, avoiding the problem of uneven distribution of the liquid cooling medium during the flow process.

[0076] In this embodiment, the single cell 20 is vertically arranged in the installation sleeve 6, and the liquid port 511 is located directly above the single cell 20. When the liquid cooling medium flows from top to bottom in the liquid cooling box, it will directly impact the top of the single cell 20. Especially when the flow rate of the liquid cooling medium is large, under a long-term working environment, the impact of the liquid cooling medium will cause damage to the single cell 20.

[0077] To this end, the solution adopted in this embodiment is to fix a circular guide plate 52 in the liquid through hole 511, and an annular channel 521 is provided between the guide plate 52 and the liquid through hole 511, and the annular channel 521 corresponds to the cooling liquid channel 61. With this arrangement, most of the liquid cooling medium in the diversion cavity 51 can flow out through the annular channel 521 and enter the cooling liquid channel 61, and the liquid cooling medium flows downward along the cooling liquid channel 61, which can reduce the direct impact of the liquid cooling medium on the top surface of the single battery cell 20, and avoid physical damage to the single battery cell 20 caused by long-term high flow impact.

[0078] In this embodiment, the guide plate 52 can be fixedly connected to the inside of the liquid cooling box 5 through a connecting rod, and the guide plate 52 can also be connected to the inner wall of the liquid passage 511 through a connecting rod.

[0079] As an embodiment, the bottom surface of the liquid cooling box 5 is in contact with the top surface of the upper partition 12. With this arrangement, the liquid cooling medium can enter the cooling liquid channel 61 more directly and quickly, reducing the flow resistance and time delay, and improving the flow efficiency of the liquid cooling medium. At the same time, each liquid through hole 511 corresponds to a single battery cell 20, and the liquid cooling medium directly enters the cooling liquid channel 61 through the annular channel 521. The independent flow path ensures that the liquid cooling medium flow path of each single battery cell 20 is uniform and efficient. This independent cooling method helps to balance the temperature of each single battery cell 20, avoid local overheating or insufficient cooling, thereby extending the battery life and improving system safety.

[0080] When the liquid cooling box 5 needs to be fed with a high flow rate of liquid cooling medium, it indicates that the phase change material 4 has been completely melted. Although the liquid cooling medium can enter the upper chamber 101 through the first through hole 63, the amount of the liquid cooling medium entering is limited. More liquid cooling medium will flow directly downward from the coolant channel 61 to the lower chamber 102. In this way, the process of the phase change material 4 transforming from liquid to fixed is relatively slow, which is not conducive to phase change conversion.

[0081] To this end, the solution adopted in this embodiment is: a gap is set between the bottom surface of the liquid cooling box 5 and the upper partition 12, and a plurality of third through holes 121 connected to the upper chamber 101 are opened on the upper partition 12. Therefore, the liquid cooling medium flowing out of the annular channel will fill the space between the upper partition 12 and the liquid cooling box 5, and this part of the liquid cooling medium is in a flowing low-temperature coolant, and when these liquid cooling media flow, a part of them quickly passes through the coolant channel 61 to achieve heat exchange with the single battery cell 20, and the other part passes through the third through hole 121 into the upper chamber 101 to achieve the conversion of the phase change material 4 from liquid to solid, so that the phase change material 4 can be quickly recovered, and then repeatedly exert its heat absorption effect, and improve the heat dissipation efficiency of the single battery cell 20. This process belongs to a dynamic conversion process.

[0082] It is worth noting that when in static immersion liquid cooling, the liquid cooling medium is filled in the battery pack body 1 and the liquid cooling box 5. Therefore, the liquid cooling medium is also filled in the upper chamber 101, thereby achieving efficient contact and heat exchange between the phase change material 4 and the liquid cooling medium.

[0083] The present invention also discloses a composite battery pack thermal management method, comprising the following steps:

[0084] S1. When the temperature of the single cell 20 is lower than 40°C and the temperature of the phase change material 4 is lower than 33°C, the coolant in the battery pack box 1 is in a static state, and the static coolant and the phase change material 4 cooperate to achieve heat dissipation of the single cell 20;

[0085] In this step, the temperature of the single battery cell 20 is measured by the first temperature sensor, the phase change temperature is measured by the second temperature sensor, and the electromagnetic flow valves on the liquid inlet 50 and the liquid outlet 11 are in a closed state.

[0086] S2. When the temperature of the single cell 20 is higher than 40°C and the temperature of the phase change material 4 is greater than 33°C and lower than 35°C, a coolant is circulated into the battery pack box 1 at a low flow rate. The coolant flows through the surface of the single cell 20 to take away the heat. At the same time, the phase change medium absorbs the heat in the coolant, and the auxiliary thermal management system realizes active and passive synchronous heat dissipation.

[0087] S3. When the temperature of the single cell 20 is higher than 40°C and the temperature of the phase change material 4 is greater than 35°C, the phase change material 4 is completely melted, and the coolant is circulated into the battery pack box 1 at a high flow rate, and the cooling method of the battery thermal management system is converted to active immersion dynamic cooling.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite battery pack thermal management system, characterized in that: include: A battery pack case (1) having a mounting cavity (10) with an opening at the top, the mounting cavity (10) being filled with a liquid cooling medium, and a liquid outlet (11) communicating with the mounting cavity (10) being provided on a bottom side wall of the battery pack case (1); A plurality of single battery cells (20) are fixedly arranged in the installation cavity (10) and immersed in a liquid cooling medium; A three-periodic minimal curved surface structure (3) is arranged in the mounting cavity (10) and surrounds the outer side of the single battery cell (20); A phase change material (4) is disposed in the pores of the three-periodic minimal surface structure (3); A liquid cooling box (5) is fixedly arranged at the top opening of the battery pack body (1) and is connected to the installation cavity (10); a liquid inlet (50) is provided on the liquid cooling box (5); The control device comprises a first temperature sensor, a second temperature sensor, an electromagnetic flow valve and a controller, wherein the first temperature sensor is arranged on a single cell (20) and is used to detect the temperature of the single cell (20), the second temperature sensor is used to detect the temperature of a phase change material (4), the electromagnetic flow valve is arranged at a liquid inlet (50) and a liquid outlet (11), respectively, the first temperature sensor, the second temperature sensor and the electromagnetic flow valve are electrically connected to the controller respectively, and the controller controls the opening and closing of the electromagnetic flow valve and the flow rate of a liquid cooling medium according to the acquired temperature data.

2. The composite battery pack thermal management system according to claim 1, characterized in that: An upper partition (12) and a lower partition (13) are fixedly arranged in the installation cavity (10) from top to bottom. The upper partition (12) and the lower partition (13) divide the installation cavity (10) into an upper chamber (101) and a lower chamber (102) that are independent of each other. A plurality of installation sleeves (6) are vertically fixedly arranged between the upper partition (12) and the lower partition (13). The single cell (20) is vertically fixedly arranged in the installation sleeve (6). A cooling liquid channel (61) is provided between the single cell (20) and the installation sleeve (6). The cooling liquid channel (61) is connected to the liquid cooling box (5) and the lower chamber (102). The liquid outlet (11) is connected to the lower chamber (102). The three-periodic minimal surface structure (3) is arranged in the upper chamber (101) and is fixedly connected to the outer wall of the installation sleeve (6).

3. The composite battery pack thermal management system according to claim 2, characterized in that: The cooling liquid channel (61) is provided with a spiral flow channel (62) fixedly connected to the inner wall of the mounting sleeve (6).

4. The composite battery pack thermal management system according to claim 2 or 3, characterized in that: A plurality of first through holes (63) are provided on the side wall of the mounting sleeve (6), a plurality of second through holes (131) are provided on the lower partition plate (13), the upper chamber (101) and the coolant channel (61) are connected via the first through holes (63), the upper chamber (101) and the lower chamber (102) are connected via the second through holes (131), and a coating layer encapsulating a phase change material (4) is also provided in the pores of the three-periodic minimal surface structure (3), wherein the coating layer is a high thermal conductivity polymer or a composite material.

5. The composite battery pack thermal management system according to claim 4, characterized in that: A plurality of single battery cells (20) are arranged to form a plurality of battery cell groups (2); a plurality of mutually independent shunt chambers (51) are arranged inside the liquid cooling box (5); each shunt chamber (51) corresponds to a battery cell group (2); a plurality of liquid through ports (511) are arranged at the bottom of the shunt chamber (51); and the plurality of liquid through ports (511) correspond one by one to the plurality of single battery cells (20) in the battery cell group (2).

6. The composite battery pack thermal management system according to claim 5, characterized in that: A guide plate (52) with a circular structure is fixedly arranged in the liquid passage (511), and an annular channel (521) is provided between the guide plate and the liquid passage (511), and the annular channel (521) corresponds to the cooling liquid channel (61).

7. The composite battery pack thermal management system according to claim 6, characterized in that: The bottom surface of the liquid cooling box (5) and the top surface of the upper partition (12) are connected.

8. The composite battery pack thermal management system according to claim 6, characterized in that: A space is provided between the bottom surface of the liquid cooling box (5) and the upper partition (12), and a plurality of third through holes (121) communicating with the upper chamber (101) are provided on the upper partition (12).

9. The composite battery pack thermal management system according to claim 1, characterized in that: The three-periodic minimal surface structure (3) is any one of a Gyroid surface structure, a Primitive surface structure, a Diamond surface structure and an I-WP surface structure.

10. A composite battery pack thermal management method, which utilizes the composite battery pack thermal management system according to any one of claims 2 to 9, characterized in that: The steps include: S1. When the temperature of the single cell is lower than 40°C and the temperature of the phase change material is lower than 33°C, the coolant in the battery pack is in a static state, and the static coolant and the phase change material work together to achieve heat dissipation of the single cell; S2. When the temperature of the single cell is higher than 40°C and the temperature of the phase change material is greater than 33°C and lower than 35°C, coolant is circulated into the battery pack at a low flow rate. The coolant flows through the surface of the single cell to take away the heat. At the same time, the phase change medium absorbs the heat in the coolant, assisting the thermal management system to achieve active and passive synchronous heat dissipation; S3. When the temperature of the single cell is higher than 40°C and the temperature of the phase change material is greater than 35°C, the phase change material is completely melted and the coolant is circulated into the battery pack at a high flow rate. The cooling method of the battery thermal management system is converted to active immersion dynamic cooling.

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