Battery pack

Abstract

The utility model relates to the technical field of energy storage devices, and discloses a battery pack which comprises a shell, a battery module, an inlet enclosing plate and an outlet enclosing plate, wherein the inlet enclosing plate is arranged outside the first end face, close to one side of the branch liquid inlet, of the module support, and the first opening faces the liquid inlet cavity; the outlet enclosing plate is arranged outside the second end face, close to one side of the branch liquid outlet, of the module support, the outlet enclosing plate and the second end face define a closed channel with one side being a second opening, and the second opening faces the liquid outlet cavity. The battery pack with the structure adopts an immersion cooling mode. In the cooling process, cooling liquid flows in the axial direction of the cylindrical batteries and flows in parallel to pass through the cylindrical batteries, the cooling effect is good, the overall temperature difference of the battery cells is reduced by half, the temperature uniformity of the battery cells is improved by more than one time, the battery cells at different positions in the battery cells can be effectively cooled, the temperature difference of the battery cells is reduced, and the service life of the battery cells is prolonged. And the temperature distribution uniformity of the battery cell is improved.

Description

Technical Field

[0001] This utility model relates to the field of energy storage device technology, specifically to a battery pack. Background Technology

[0002] To ensure optimal battery performance, it typically needs to operate within a suitable temperature range. Excessively high or low temperatures, or large temperature differences, can negatively impact the battery pack's performance. Therefore, a suitable thermal management system must be selected based on the lithium-ion battery's operating environment to create a suitable operating temperature environment. As battery charge / discharge rates increase, traditional air cooling, liquid cooling, and direct cooling methods are insufficient to support prolonged high-rate charge / discharge cycles. Immersion cooling can achieve rapid cooling, but existing immersion cooling structures result in significant temperature differences between cells within the battery pack, leading to poor temperature uniformity. Utility Model Content

[0003] In view of this, the present invention provides a battery pack to solve the problems of large temperature difference and poor temperature uniformity of battery cells after cooling by immersion cooling method in the prior art.

[0004] In a first aspect, this utility model provides a battery pack, comprising:

[0005] The casing has a main liquid inlet and a main liquid outlet.

[0006] A battery module is disposed within the housing; the battery module includes multiple cylindrical batteries and a module support; the module support has a receiving cavity, the cylindrical batteries are disposed within the receiving cavity, and adjacent cylindrical batteries are arranged in parallel and spaced apart to form a liquid passage; each cylindrical battery has a liquid inlet and a liquid outlet on the module support at both ends of its axial direction; the two end faces of the module support perpendicular to the axial direction of the cylindrical batteries respectively form a liquid inlet cavity and a liquid outlet cavity with the side wall of the housing;

[0007] An inlet enclosure plate is disposed outside the first end face of the module bracket near its liquid inlet. The inlet enclosure plate and the first end face form a closed channel with a first opening on one side, and the first opening faces the liquid inlet cavity.

[0008] An outlet enclosure plate is disposed outside the second end face of the module bracket near its liquid outlet. The outlet enclosure plate and the second end face form a closed channel with a second opening on one side, and the second opening faces the liquid outlet cavity.

[0009] Beneficial Effects: This battery pack structure employs an immersion cooling method. During cooling, coolant enters the inlet chamber inside the casing through the main inlet. The coolant level gradually rises to a certain height before entering the battery module through the first opening, then through the sub-inlets into the module support. The coolant flows axially along the cylindrical cells towards the outlet of the liquid channel, then flows through the second outlet to the outlet chamber, and finally exits the casing through the main outlet, completing the cooling process. During cooling, the coolant flows axially along the cylindrical cells, circulating parallel through each cell, resulting in excellent cooling performance. The overall temperature difference between the cells is reduced by half, and the temperature uniformity of the cells is more than doubled. This effectively cools cells in different locations within the battery pack, reducing temperature differences and improving the uniformity of cell temperature distribution.

[0010] In one alternative embodiment, an acceleration structure is further included, wherein the acceleration structure is disposed at the downstream end of the liquid passage, and the acceleration structure is used to reduce the cross-sectional area of ​​the downstream end of the liquid passage to increase the flow rate of the coolant.

[0011] Beneficial effects: The accelerated structure is set at the downstream end of the liquid passage. The accelerated structure is used to reduce the cross-sectional area of ​​the downstream end of the liquid passage to increase the flow rate of the coolant. This setting can ensure the flow rate of the coolant to the downstream end of the liquid passage, ensure that the coolant is separated in each liquid passage, and at the same time ensure that the coolant flows out from the outlet of the liquid passage to the second opening.

[0012] In one alternative embodiment, the cross-sectional area of ​​the acceleration structure, perpendicular to the liquid passage, gradually increases toward the outlet end of the liquid passage.

[0013] In one optional embodiment, the outer edge of the first end face protrudes to provide a first enclosure structure, and the side wall of the inlet enclosure plate is sealed to the first enclosure structure; and / or, the outer edge of the second end face protrudes to provide a second enclosure structure, and the side wall of the outlet enclosure plate is sealed to the second enclosure structure.

[0014] In one optional embodiment, the module support includes a first support and a second support arranged opposite to each other, with openings on opposite sides of the first support and the second support; the liquid inlet is provided on the first support, and the liquid outlet is provided on the second support; a limiting structure is provided on the inner wall of the first support at the outer edge of the liquid inlet and on the inner wall of the second support at the outer edge of the liquid outlet, and both ends of the cylindrical battery are fixed on the limiting structure.

[0015] In one optional embodiment, the limiting structure includes a connecting portion and a limiting portion. The connecting portion is disposed on the first bracket or the second bracket, and the limiting portion is disposed on the connecting portion. The limiting portion extends along the axial direction of the cylindrical battery. Multiple limiting structures are provided, and the multiple limiting structures are arranged at intervals along the circumferential direction of the liquid inlet or the liquid outlet. The limiting portion abuts against the outer wall surface of the cylindrical battery.

[0016] In one optional embodiment, the battery module is provided with multiple sets, and the inlet enclosure plate of adjacent battery modules is connected to the outlet enclosure plate;

[0017] The battery pack also includes a module pressure plate, which surrounds the battery module. The module pressure plate located outside the first opening of the battery module in the middle is provided with a module liquid inlet; the module pressure plate located outside the second opening is provided with a module liquid outlet.

[0018] In one optional embodiment, a liquid outlet pipe is further included, which extends into the liquid outlet cavity through the main liquid outlet and is provided with a plurality of slots at intervals along the axial direction of the cylindrical battery.

[0019] In one optional embodiment, along the axial direction of the cylindrical battery, the front and rear end faces of the battery module are spaced apart from the housing to form a front cavity and a rear cavity at the front and rear ends of the battery module, respectively.

[0020] The battery pack also includes a first barrier plate and a second barrier plate. The first barrier plate is sealed between the housing and the battery module at the front end of the liquid outlet chamber, and the second barrier plate is disposed between the housing and the battery module at the end of the liquid inlet chamber.

[0021] In one optional embodiment, a liquid inlet baffle is further included. The liquid inlet baffle is disposed inside the outlet side of the main liquid inlet. The liquid inlet baffle extends from the front end cavity toward the liquid inlet cavity and is used to guide the coolant to flow toward the liquid inlet cavity. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram showing the flow direction of coolant in an immersion cooling structure in related technologies;

[0024] Figure 2 This is a three-dimensional structural diagram of a battery pack according to an embodiment of the present utility model;

[0025] Figure 3 This is an exploded view of a battery pack according to an embodiment of the present utility model;

[0026] Figure 4 This is an exploded view of a battery pack according to an embodiment of the present utility model;

[0027] Figure 5 This is a top view of a battery pack according to an embodiment of the present utility model;

[0028] Figure 6 This is an exploded view of a battery module in a battery pack according to an embodiment of the present invention;

[0029] Figure 7 for Figure 5 Enlarged view of part A in the middle;

[0030] Figure 8 for Figure 5 Enlarged view of part B in the middle;

[0031] Figure 9 This is a schematic diagram of the second support.

[0032] Figure 10 This is a schematic diagram showing the direction of liquid flow inside the battery pack.

[0033] Figure 11 A temperature distribution diagram of the cells within a battery pack as coolant flows radially along the cylindrical battery.

[0034] Figure 12 This is a temperature distribution diagram of the cells within a battery pack where coolant flows along the axial direction of the cylindrical battery.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Housing; 101. First housing; 102. Second housing; 2. Battery module; 201. Cylindrical battery; 202. Module bracket; 2021. Receiving cavity; 2022. First bracket; 20221. Liquid inlet; 20222. First end face; 20223. First enclosure structure; 2023. Second bracket; 20231. Liquid outlet; 20232. Second end face; 20233. Second enclosure structure; 2024. Limiting structure; 20241. Connecting... 1. Connecting part; 2. Limiting part; 2. Liquid passage; 2. Liquid inlet chamber; 2. Liquid outlet chamber; 2. Accelerating structure; 3. Inlet enclosure plate; 4. Outlet enclosure plate; 5. First opening; 6. Second opening; 7. Module pressure plate; 701. Module liquid inlet; 702. Module liquid outlet; 8. Liquid outlet pipe; 801. Slot; 9. Liquid inlet pipe; 10. Front cavity; 11. Rear cavity; 12. First baffle plate; 13. Second baffle plate; 14. Liquid inlet baffle. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0038] like Figure 1 As shown, in the related technology, the immersion cooling method involves the coolant flowing radially along the cylindrical battery. While this method can achieve rapid cooling, it also has limitations. Figure 11 As shown, after cooling, the temperature difference between the cells in the battery pack is large, and the temperature uniformity of the cells is poor.

[0039] The following is combined with Figures 2 to 10 and Figure 12 The following describes embodiments of the present invention.

[0040] According to an embodiment of the present invention, a battery pack is provided, including a housing 1, a battery module 2, an inlet enclosure 3, and an outlet enclosure 4.

[0041] The housing 1 has a main liquid inlet and a main liquid outlet; the battery module 2 is disposed inside the housing 1; the battery module 2 includes multiple cylindrical batteries 201 and a module support 202; the module support 202 has a receiving cavity 2021, the cylindrical batteries 201 are disposed in the receiving cavity 2021, and adjacent cylindrical batteries 201 are arranged in parallel and spaced apart to form liquid passages 203; each cylindrical battery 201 has a separate liquid inlet 20221 and a separate liquid outlet 20231 on the module support 202 at both ends of its axial direction; the two end faces of the module support 202 perpendicular to the axial direction of the cylindrical batteries 201 are respectively connected to the housing 1. The side walls of the module support 202 form an inlet chamber 204 and an outlet chamber 205. The inlet enclosure plate 3 is disposed outside the first end face 20222 of the module support 202 near its sub-inlet port 20221. The inlet enclosure plate 3 and the first end face 20222 form a closed channel with a first opening 5 on one side, and the first opening 5 faces the inlet chamber 204. The outlet enclosure plate 4 is disposed outside the second end face 20232 of the module support 202 near its sub-outlet port 20231. The outlet enclosure plate 4 and the second end face 20232 form a closed channel with a second opening 6 on one side, and the second opening 6 faces the outlet chamber 205.

[0042] This battery pack uses an immersion cooling method. During cooling, coolant enters the inlet chamber 204 inside the housing 1 from the main inlet. The coolant level gradually rises to a certain height and then enters the battery module 2 through the first opening 5. It then enters the module support 202 through the sub-inlet 20221. The coolant flows axially along the cylindrical battery 201 towards the outlet of the liquid channel 203, then flows from the second outlet to the outlet chamber 205, and finally flows out of the housing 1 from the main outlet, completing the cooling process. Figure 12 As shown, during the cooling process, the coolant flows along the axial direction of the cylindrical battery 201. The coolant flows in parallel through each cylindrical battery 201, resulting in a good cooling effect. The overall temperature difference of the battery cell is reduced by half, and the temperature uniformity of the battery cell is more than doubled. It can effectively cool the battery cells at different locations within the battery, reduce the temperature difference of the battery cells, and improve the uniformity of the temperature distribution of the battery cells.

[0043] The coolant flow rate is faster at the upstream end of the liquid passage 203 and slower at the downstream end. Since the receiving cavity 2021 of the module bracket 202 is a fully interconnected cavity, the slower flow rates of the coolant in different liquid passages 203 can easily lead to mixing and cross-flow, affecting the cooling effect. To avoid this problem, in some embodiments, such as... Figure 9 and Figure 10As shown, the battery pack also includes an acceleration structure 206, which is located at the downstream end of the liquid passage 203. The acceleration structure 206 is used to reduce the cross-sectional area of ​​the downstream end of the liquid passage 203 to increase the flow rate of the coolant. This arrangement can ensure the flow rate of the coolant to the downstream end of the liquid passage 203, ensure that the coolant is separated in each liquid passage 203, and at the same time ensure that the coolant flows out from the outlet of the liquid passage 203 to the second opening 6.

[0044] Optionally, in some embodiments, the cross-sectional area of ​​the accelerating structure 206 perpendicular to the liquid passage 203 gradually increases towards the outlet end of the liquid passage 203. This arrangement causes the cross-sectional area of ​​the downstream end of the liquid passage 203 to gradually decrease, which can effectively ensure the flow rate of the coolant at the downstream end.

[0045] In some embodiments, the cross-section of the acceleration structure 206 perpendicular to the axial direction of the cylindrical battery 201 is triangular. The acceleration structure 206 is integrally formed on the module bracket 202.

[0046] like Figure 2 , Figure 7 and Figure 8 As shown, in some embodiments, the outer edge of the first end face 20222 is provided with a first enclosure structure 20223. The side wall of the inlet enclosure plate 3 is sealed to the first enclosure structure 20223. The inlet enclosure plate 3 and the first enclosure structure 20223 form a closed channel with a first opening 5 on one side, ensuring that the coolant can enter the closed channel from the first opening 5 and flow into the module bracket 202 from the closed channel and the liquid inlet 20221 on the module bracket 202.

[0047] The outer edge of the second end face 20232 is provided with a second enclosure structure 20233. The side wall of the outlet enclosure plate 4 is sealed to the second enclosure structure 20233. The outlet enclosure plate 4 and the second enclosure structure 20233 form a closed channel with a second opening 6 on one side, ensuring that the coolant can flow from the outlet port 20231 to the closed channel, and then flow out of the battery module 2 from the closed channel and the second opening 6.

[0048] In some embodiments, the module bracket 202 has a rectangular cross-section perpendicular to the coolant flow direction, and both the inlet enclosure plate 3 and the outlet enclosure plate 4 are rectangular plates. A first enclosure structure 20223 is provided on three adjacent sides of the first end face 20222 of the module bracket 202, and its end facing the inlet cavity 204 forms a first opening 5 with the inlet enclosure plate 3. A second enclosure structure 20233 is provided on three adjacent sides of the second end face 20232 of the module bracket 202, and its end facing the outlet cavity 205 forms a second opening 6 with the outlet enclosure plate 4.

[0049] In some embodiments, such as Figure 6 and Figure 10 As shown, the module support 202 includes a first support 2022 and a second support 2023 arranged opposite to each other, with openings on opposite sides of the first support 2022 and the second support 2023. A liquid inlet 20221 is located on the first support 2022, and a liquid outlet 20231 is located on the second support 2023. Limiting structures 2024 are provided on the inner wall of the first support 2022 at the outer edge of the liquid inlet 20221 and on the inner wall of the second support 2023 at the outer edge of the liquid outlet 20231. Both ends of the cylindrical battery 201 are fixed to the limiting structures 2024. When assembling the battery module 2, the cylindrical battery 201 is first fixed to the limiting structures 2024 of the second support 2023, and then the first support 2022 is joined and fixed to the second support 2023, facilitating the assembly of the battery module 2. The limiting structure 2024 fixes the cylindrical battery 201 inside the liquid inlet 20221, which facilitates the coolant to enter the outer periphery of each cylindrical battery 201 through each liquid inlet hole and flow along the axial direction of each battery, preventing cross-flow of coolant and improving the heat exchange effect of the battery.

[0050] In some embodiments, the cylindrical battery 201 is bonded to the connecting portion 20241 with structural adhesive, and the first bracket 2022 is bonded to the second bracket 2023. Both the first bracket 2022 and the second bracket 2023 are rectangular frames with one open side.

[0051] like Figure 8 As shown, in some embodiments, the limiting structure 2024 includes a connecting portion 20241 and a limiting portion 20242. The connecting portion 20241 is disposed on the first bracket 2022 or the second bracket 2023, and the limiting portion 20242 is disposed on the connecting portion 20241. The limiting portion 20242 extends along the axial direction of the cylindrical battery 201. Multiple limiting structures 2024 are provided, and these multiple limiting structures 2024 are arranged at intervals along the circumferential direction of the liquid inlet 20221 or the liquid outlet 20231. The limiting portion 20242 abuts against the outer wall surface of the cylindrical battery 201. The cylindrical battery 201 is fixed to the connecting portion 20241, and the limiting portion 20242 circumferentially limits the cylindrical battery 201. The limiting structure 2024 simultaneously serves to fix and circumferentially limit the cylindrical battery 201. Multiple limiting structures 2024 are arranged circumferentially along the liquid inlet 20221 or liquid outlet 20231, which saves material compared to a single ring-shaped limiting component.

[0052] Optionally, the limiting structure 2024 is integrally formed on the first bracket 2022 and the second bracket 2023.

[0053] In some embodiments, such as Figure 6 and Figure 10As shown, the battery module 2 is provided in multiple sets, with the inlet enclosure plate 3 and outlet enclosure plate 4 of adjacent battery modules 2 connected. The battery pack also includes a module pressure plate 7, which surrounds the battery module 2. A module inlet 701 is provided on the module pressure plate 7 outside the first opening 5 of the battery module 2 located in the middle; a module outlet 702 is provided on the module pressure plate 7 outside the second opening 6. By opening the module inlet 701 and module outlet 702 at designated positions on the module pressure plate 7, coolant can enter the interior of each battery module 2 in parallel from the module inlet 701, which is beneficial for heat exchange in each battery module 2, helps reduce the temperature difference between batteries inside different battery modules 2, and improves the uniformity of battery temperature. The battery pack includes multiple battery modules 2, which helps to increase the capacity of the battery pack.

[0054] like Figure 2 and Figure 10 As shown, the direction closer to the main liquid inlet is the front end, and the direction closer to the main liquid outlet is the rear end. In some embodiments, the front end of the inlet enclosure plate 3 of the first battery module 2 is not provided with a module pressure plate 7, and the first opening 5 of the first battery module 2 exposes the module pressure plate 7. The coolant directly enters the interior of the first battery module 2 from the first opening 5. For subsequent battery modules 2, the coolant enters the first opening 5 from the module inlet 701, and then enters the interior of the battery module 2 from the first opening 5. After heat exchange, the coolant flows out from the second opening 6 and the module outlet 702 to the outlet chamber 205.

[0055] like Figure 4 and Figure 5 As shown, in some embodiments, the battery pack also includes a liquid outlet pipe 8, which extends into the liquid outlet cavity 205 through a main liquid outlet. Along the axial direction of the cylindrical battery 201, the liquid outlet pipe 8 has multiple slots 801 spaced apart. The main liquid outlet is located on the housing 1 behind the last battery module 2. The coolant flowing out from the module liquid outlet 702 on the front battery module 2 needs to flow towards the main liquid outlet. During this process, the coolant may flow into the battery module 2 from the module liquid outlet 702 on the corresponding side of the next battery module 2, causing cross-contamination of hot and cold liquids. This invention, by extending the liquid outlet pipe 8 into the liquid outlet cavity 205 and creating multiple slots 801 spaced apart along the length of the liquid outlet pipe 8, allows the coolant flowing into the liquid outlet cavity 205 to directly flow into the liquid outlet pipe 8 through the slots 801 and then out of the housing 1 from the liquid outlet pipe 8. This effectively prevents cross-contamination of hot and cold liquids and helps to maximize heat exchange efficiency.

[0056] In some embodiments, the battery pack further includes an inlet pipe 9 connected to a main inlet.

[0057] like Figures 1 to 5As shown, in some embodiments, along the axial direction of the cylindrical battery 201, the front and rear end faces of the battery module 2 are spaced apart from the housing 1 to form a front cavity 10 and a rear cavity 11 at the front and rear ends of the battery module 2, respectively. The battery pack also includes a first barrier plate 12 and a second barrier plate 13. The first barrier plate 12 is sealed between the housing 1 at the front end of the liquid outlet cavity 205 and the battery module 2, and the second barrier plate 13 is disposed between the housing 1 at the end of the liquid inlet cavity 204 and the battery module 2. The front and rear end faces of the battery module 2 are spaced apart from the housing 1 to reserve installation space for easy installation of the battery module 2. There are gaps between the front and rear ends of the battery module 2 and the housing 1, and the reserved installation gaps are small. The coolant entering from the inlet tends to flow directly from the front cavity 10 and the rear cavity 11 to the outlet cavity 205. To prevent this phenomenon, a first barrier plate 12 is set between the housing 1 at the front end of the outlet cavity 205 and the battery module 2, and a second barrier plate 13 is set between the housing 1 at the end of the inlet cavity 204 and the battery module 2. This blocks the communication channel between the front cavity 10, the rear cavity 11 and the outlet cavity 205, ensuring that the coolant in the inlet cavity 204 enters the battery module 2 from the first opening 5 and the module inlet 701 for heat exchange before flowing to the outlet cavity 205.

[0058] In some embodiments, such as Figure 5 As shown, the battery pack also includes a liquid inlet baffle 14, which is located inside the outlet side of the main liquid inlet. The liquid inlet baffle 14 extends from the front cavity 10 toward the liquid inlet cavity 204. The liquid inlet baffle 14 is used to guide the coolant to flow toward the liquid inlet cavity 204, so that the coolant enters the liquid inlet cavity 204 first and then enters the battery module 2, thereby ensuring the cooling effect.

[0059] like Figure 3 and Figure 4 As shown, the housing 1 includes a first housing 101 and a second housing 102 arranged opposite each other. The housing 1 is divided into two parts, which facilitates the assembly of the battery pack.

[0060] When assembling the battery pack, first assemble each battery module 2, then bond two battery modules 2 together using the outlet enclosure plate 4 and the inlet enclosure plate 3, then place the battery modules 2 inside the lower second housing 102, press all the battery modules 2 with the module pressure plate 7 to fix the battery modules 2, and then fix the first barrier plate 12 and the second barrier plate 13 on the module pressure plate 7 so that the other ends of the first barrier plate 12 and the second barrier plate 13 are in contact with the inner wall of the second housing 102.

[0061] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery pack, characterized in that, include: The casing has a main liquid inlet and a main liquid outlet. A battery module is disposed within the housing; the battery module includes multiple cylindrical batteries and a module support; the module support has a receiving cavity, the cylindrical batteries are disposed within the receiving cavity, and adjacent cylindrical batteries are arranged in parallel and spaced apart to form a liquid passage; each cylindrical battery has a liquid inlet and a liquid outlet on the module support at both ends of its axial direction; the two end faces of the module support perpendicular to the axial direction of the cylindrical batteries respectively form a liquid inlet cavity and a liquid outlet cavity with the side wall of the housing; An inlet enclosure plate is disposed outside the first end face of the module bracket near its liquid inlet. The inlet enclosure plate and the first end face form a closed channel with a first opening on one side, and the first opening faces the liquid inlet cavity. An outlet enclosure plate is disposed outside the second end face of the module bracket near its liquid outlet. The outlet enclosure plate and the second end face form a closed channel with a second opening on one side, and the second opening faces the liquid outlet cavity.

2. The battery pack according to claim 1, characterized in that, It also includes an acceleration structure, which is located at the downstream end of the liquid passage. The acceleration structure is used to reduce the cross-sectional area of ​​the downstream end of the liquid passage in order to increase the flow rate of the coolant.

3. The battery pack according to claim 2, characterized in that, Towards the outlet end of the liquid passage, the cross-sectional area of ​​the acceleration structure perpendicular to the liquid passage gradually increases.

4. The battery pack according to any one of claims 1 to 3, characterized in that, The outer edge of the first end face protrudes to provide a first enclosure structure, and the side wall of the inlet enclosure plate is sealed to the first enclosure structure, and / or, the outer edge of the second end face protrudes to provide a second enclosure structure, and the side wall of the outlet enclosure plate is sealed to the second enclosure structure.

5. The battery pack according to any one of claims 1 to 3, characterized in that, The module support includes a first support and a second support arranged opposite to each other, with openings on opposite sides of the first support and the second support; the liquid inlet is provided on the first support, and the liquid outlet is provided on the second support; a limiting structure is provided on the inner wall of the first support at the outer edge of the liquid inlet and on the inner wall of the second support at the outer edge of the liquid outlet, and both ends of the cylindrical battery are fixed on the limiting structure.

6. The battery pack according to claim 5, characterized in that, The limiting structure includes a connecting part and a limiting part. The connecting part is disposed on the first bracket or the second bracket, and the limiting part is disposed on the connecting part. The limiting part extends along the axial direction of the cylindrical battery. Multiple limiting structures are provided, and the multiple limiting structures are arranged at intervals along the circumference of the liquid inlet or the liquid outlet. The limiting part abuts against the outer wall surface of the cylindrical battery.

7. The battery pack according to any one of claims 1 to 3, characterized in that, The battery module is provided with multiple sets, and the inlet enclosure plate and the outlet enclosure plate of adjacent battery modules are connected; The battery pack also includes a module pressure plate, which surrounds the battery module. The module pressure plate located outside the first opening of the battery module in the middle is provided with a module liquid inlet; the module pressure plate located outside the second opening is provided with a module liquid outlet.

8. The battery pack according to claim 7, characterized in that, It also includes a liquid outlet pipe, which extends into the liquid outlet cavity through the main liquid outlet and is provided with multiple slots at intervals along the axial direction of the cylindrical battery.

9. The battery pack according to any one of claims 1 to 3, characterized in that, Along the axial direction of the cylindrical battery, the front and rear end faces of the battery module are spaced apart from the housing to form a front cavity and a rear cavity at the front and rear ends of the battery module, respectively. The battery pack also includes a first barrier plate and a second barrier plate. The first barrier plate is sealed between the housing and the battery module at the front end of the liquid outlet chamber, and the second barrier plate is disposed between the housing and the battery module at the end of the liquid inlet chamber.

10. The battery pack according to claim 9, characterized in that, It also includes an inlet baffle, which is located inside the outlet side of the main inlet. The inlet baffle extends from the front end cavity toward the inlet cavity and is used to guide the coolant to flow toward the inlet cavity.

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