Immersed liquid-cooled battery pack

Abstract

The invention discloses an immersed liquid-cooled battery pack, the immersed liquid-cooled battery pack comprises a bottom liquid-cooled plate and an immersion liquid, the bottom liquid-cooled plate is used for indirectly dissipating heat for the bottom of a battery cell of a battery pack in the immersed liquid-cooled battery pack through the immersion liquid, and the immersion liquid is used for directly dissipating heat for the immersed liquid-cooled battery pack. By adopting a heat dissipation mode of combining indirect liquid cooling heat dissipation of the bottom liquid cooling plate with immersed liquid cooling heat dissipation, efficient and uniform heat dissipation is provided for the battery cell.

Description

Technical Field

[0001] The present application relates to the technical field of battery packs, and in particular to an immersion liquid-cooled battery pack. Background Art

[0002] Immersion cooling is to immerse the battery cells directly in a non-toxic, insulating, high thermal conductivity, and high specific heat capacity immersion liquid, so that the battery cells are in direct contact with the immersion liquid for heat exchange, thereby improving the heat dissipation performance of the battery cells and the temperature uniformity between the battery cells.

[0003] Immersion liquid cooling, due to direct heat exchange with the battery cells, offers higher heat transfer efficiency than indirect liquid cooling using a cold plate. However, this requires more sophisticated flow channel design. Irregular flow patterns can easily lead to localized dead zones, causing heat accumulation and affecting the battery pack's temperature characteristics. Furthermore, flow channel design must also consider sealing and processability. Overly complex flow channel designs may not guarantee structural sealing throughout, and will also result in difficult processing and high costs.

[0004] Furthermore, considering that submerged liquid-cooled battery packs typically immerse all materials within the battery pack box (such as battery cells, wiring harnesses, BMUs, fuses, etc.) in the immersion fluid, this solution simplifies the design and processing of the battery pack box, and all internal materials are located in the same area within the box. Although this solution can reduce the battery pack volume compared to semi-submerged battery packs, holes must be opened on the front of the battery pack to accommodate through-wall terminals, connectors, liquid injection and discharge ports, and immersion fluid inlet and outlet, making the immersion fluid prone to leakage. Summary of the Invention

[0005] An embodiment of the present application provides an immersion liquid-cooled battery pack to provide efficient and uniform heat dissipation for battery cells through direct heat dissipation and indirect heat dissipation.

[0006] The embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides an immersion liquid-cooled battery pack, wherein the immersion liquid-cooled battery pack includes: a bottom liquid cooling plate and an immersion liquid, the bottom liquid cooling plate is used to indirectly dissipate heat from the bottom of the battery cell of the battery pack in the immersion liquid-cooled battery pack through the immersion liquid, and the immersion liquid is used to directly dissipate heat from the immersion liquid-cooled battery pack.

[0008] In some embodiments, the immersion liquid flows to the tail of the bottom liquid cooling plate and is then sprayed into the battery pack through the through hole. The sprayed immersion liquid flows from the tail of the battery pack to the head of the battery pack, directly contacts the battery cells and takes away the heat of the battery cells. The liquid inlet and outlet of the immersion liquid-cooled battery pack are connected to an external liquid cooling unit, and the immersion liquid circulates through the operation of the pump of the external liquid cooling unit.

[0009] In some embodiments, the temperature cascade effects generated by the immersion liquid when the bottom liquid cooling plate cools the battery cells and after the immersion liquid is sprayed out of the tail of the bottom liquid cooling plate offset each other.

[0010] In some embodiments, a flow separator is further included to divide the battery pack into a dry area and a wet area, and the immersion liquid reserves the dry area as a buffer area between the wet area and the battery pack.

[0011] In some embodiments, the BMU is disposed in the dry area, and a maintenance window is provided on the box cover corresponding to a position directly above the BMU.

[0012] In some embodiments, the immersion liquid is spread throughout the wet area, the immersion liquid-cooled battery pack is located in the wet area, and the immersion liquid is used to immerse the battery cells of the battery pack in the immersion liquid-cooled battery pack and the CCS and wiring harness connected to the battery cells.

[0013] In some embodiments, an explosion-proof valve is provided on the upper cover of the battery pack.

[0014] In some embodiments, gaps are reserved between the battery cells of the battery pack in the immersion liquid-cooled battery pack, gaps are reserved between the two rows of battery cells on the outside and the inner walls of the box on the left and right sides, and gaps are reserved between the battery pack and the lower surface of the upper box cover. The multiple reserved gaps serve as flow channels for the immersion liquid in the battery pack.

[0015] In some embodiments, a liquid inlet is provided at the top of the bottom liquid cooling plate for immersion liquid to flow into the liquid cooling plate flow channel; a plurality of through holes are provided at the tail of the bottom liquid cooling plate, and the plurality of through holes are located in the battery pack in an area between the inner wall of the back side of the battery pack and the end of the battery cell, for connecting the flow channel with the inner area of ​​the battery pack.

[0016] In some embodiments, a thermally conductive adhesive layer is provided between the battery cells in the battery pack of the immersion liquid-cooled battery pack and the bottom of the box.

[0017] At least one of the above-mentioned technical solutions employed in the embodiments of the present application can achieve the following beneficial effects: The immersion-cooled battery pack includes a bottom liquid cooling plate and an immersion liquid. The bottom liquid cooling plate is used to indirectly dissipate heat from the bottom of the battery cells in the immersion-cooled battery pack via the immersion liquid, and the immersion liquid is used to directly dissipate heat from the immersion-cooled battery pack. This combination of indirect liquid cooling via the bottom liquid cooling plate and immersion liquid cooling provides efficient and uniform heat dissipation for the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 This is an axonometric view of an immersion liquid-cooled battery pack in an embodiment of the present application;

[0020] Figure 2 A top view of an immersion liquid-cooled battery pack in an embodiment of the present application;

[0021] Figure 3 For the immersion liquid-cooled battery pack in the embodiment of this application Figure 1 The main view;

[0022] Figure 4 For the immersion liquid-cooled battery pack in the embodiment of this application Figure 1 Side view of

[0023] Figure 5 This is an axial view of a battery module in an immersion liquid-cooled battery pack in an embodiment of the present application;

[0024] Figure 6 This is an axial view of the lower box of the immersion liquid-cooled battery pack in an embodiment of the present application;

[0025] Figure 7 Schematic diagram of a flow baffle of an immersion liquid-cooled battery pack in an embodiment of the present application;

[0026] Figure 8 Schematic diagram of a liquid cooling plate of an immersion liquid-cooled battery pack in an embodiment of the present application;

[0027] Figure 9 This is one of the schematic diagrams of the flow of immersion liquid in an immersion liquid-cooled battery pack in an embodiment of the present application;

[0028] Figure 10 This is the second schematic diagram of the flow of immersion liquid in the immersion liquid-cooled battery pack in the embodiment of the present application. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] The following describes in detail the technical solutions provided by various embodiments of the present application in conjunction with the accompanying drawings.

[0031] The present application embodiment provides an immersion liquid-cooled battery pack, such as Figure 1As shown, an axonometric view of an immersion liquid-cooled battery pack in an embodiment of the present application is provided, wherein the immersion liquid-cooled battery pack comprises: a bottom liquid cooling plate 1 and an immersion liquid, wherein the bottom liquid cooling plate 1 is used to indirectly dissipate heat for the bottom of the battery cell of the battery pack in the immersion liquid-cooled battery pack through the immersion liquid, and the immersion liquid is used to directly dissipate heat for the immersion liquid-cooled battery pack.

[0032] To distinguish between indirect and direct heat dissipation, the "immersion liquid" in the bottom liquid cooling plate 1 in the present embodiment serves as an indirect heat dissipation carrier, indirectly dissipating heat from the bottom of the battery cells in the immersion-cooled battery pack. The "immersion liquid" in the present embodiment is primarily used to immerse the immersion-cooled battery pack and provide direct heat dissipation. It is understood that the "immersion liquid" is an oily substance, most often a synthetic oil, and is not specifically defined in the present embodiment.

[0033] like Figure 1 and Figure 3 As shown, specifically, the heat dissipation method of the immersion liquid-cooled battery pack in the embodiment of the present application is composite heat dissipation, and includes indirect heat dissipation by the bottom liquid cooling plate and direct heat dissipation by the immersion liquid. The immersion liquid can flow into the liquid cooling plate flow channel through the inlet of the liquid cooling plate, and the flow channel design of the liquid cooling plate can evenly distribute the immersion liquid to the bottom of each battery cell module to dissipate heat from the bottom of the battery cell. After the immersion liquid flows to the tail of the liquid cooling plate, it is sprayed into the battery pack through the through hole. The sprayed immersion liquid flows from the tail of the battery pack to the head of the battery pack, directly contacts the battery cell, takes away the heat of the battery cell, and flows out through the liquid outlet on the box wall. The liquid inlet and liquid outlet of the battery pack are connected to an external liquid cooling unit, and the immersion liquid is caused to circulate by the operation of the pump of the external liquid cooling unit. As shown Figure 9 and Figure 10 shown.

[0034] When the immersion liquid is used to directly dissipate heat from the immersion liquid-cooled battery pack, there are two types of immersion liquid cooling: circulating type and static type. Among them, the circulating type requires an external dedicated liquid cooler, which relies on the pump in the immersion liquid circuit of the liquid cooler to drive the immersion liquid to circulate, and the heat absorbed by the immersion liquid is taken away by the refrigeration circuit in the liquid cooler. Among them, the static type is that the immersion liquid does not flow, and the battery cell is simply immersed in the immersion liquid. This method is usually combined with other heat dissipation methods. Another major advantage of using immersion liquid cooling for heat dissipation is that when the battery cell is in thermal runaway, the immersion liquid can quickly absorb the heat of the battery cell and take it away. At the same time, since the immersion liquid is in direct contact with the materials in the package, it needs to have good compatibility and insulation.

[0035] The immersion liquid-cooled battery pack in the embodiment of the present application has technical effects such as efficient heat dissipation, easy maintenance, and good sealing effect. In addition, the heat dissipation solution of indirect liquid cooling through the bottom liquid cooling plate combined with immersion liquid cooling can provide efficient and uniform heat dissipation for the battery cells in the battery pack.

[0036] In one embodiment of the present application, the immersion liquid flows to the tail of the bottom liquid cooling plate and is sprayed into the battery pack through the through hole. The sprayed immersion liquid flows from the tail of the battery pack to the head of the battery pack, directly contacts the battery cells and takes away the heat of the battery cells; the liquid inlet 4 and the liquid outlet 5 of the immersion liquid-cooled battery pack are connected to an external liquid cooling unit, and the immersion liquid is caused to circulate through the operation of the pump of the external liquid cooling unit.

[0037] like Figure 1 and Figure 3 As shown, the liquid inlet 4 is opened on the liquid cooling plate, the liquid outlet 5 is opened on the wall of the lower box body, and the lower box body 2 and the box cover 3 cooperate to serve as the placement space for the battery pack in the battery pack. Figure 1 As shown, it also includes a connector 6 for connecting external devices, a maintenance window 7 that provides an inspection window, an explosion-proof valve 8 with explosion-proof function, screws 9 for fixing the box cover 3, and lifting ears 24 for easy lifting and movement. Lifting ears 24 are set on both sides of the liquid cooling plate for lifting the battery pack. The flow path is as follows Figure 9 and Figure 10 shown.

[0038] like Figure 4 As shown, the rivet nut 10 and the lifting lug 24 are also included.

[0039] It should be noted that the compatibility of the materials in the box with the immersion liquid must be guaranteed as a priority.

[0040] In one embodiment of the present application, when the immersion liquid cools the battery cells on the bottom liquid cooling plate 1 and when the immersion liquid is sprayed out from the tail of the bottom liquid cooling plate 1 , the temperature cascade effects generated by the two cancel each other out.

[0041] Specifically, the immersion liquid flows in the liquid cold plate from the head to the tail of the battery pack, causing the temperature of the battery cells near the head of the battery pack to be low and the temperature of the battery cells near the tail of the battery pack to be high. After being sprayed out, the immersion liquid flows from the tail to the head of the battery pack, causing the temperature of the battery cells near the tail of the battery pack to be low and the temperature of the battery cells near the head of the battery pack to be high, which is the minimum elimination of the temperature cascade effect. The two produce a "temperature cascade effect" and will offset each other. The immersion liquid forms a "temperature cascade effect" that can offset when cooling the battery cells in the bottom liquid cold plate 1 and when the immersion liquid is sprayed out at the tail of the bottom liquid cold plate 1.

[0042] In one embodiment of the present application, a flow separator is further included to divide the battery pack into a dry area and a wet area, and the immersion liquid reserves the dry area as a buffer area between the wet area and the battery pack.

[0043] like Figure 2As shown, the function of the overflow partition 14 is to divide the battery pack into a dry area and a wet area, and to allow the immersion liquid to reserve the dry area between the wet area and the battery pack as a buffer area. By adding the overflow partition 14 in the battery pack, the battery pack is divided into two dry and wet areas, wherein the dry area is located at the head of the battery pack, and a hole for the connector to pass through is opened on the front wall of the battery pack, and a battery pack outlet is also opened. Preferably, only the partition needs to have a hole for the through-wall terminal to pass through on the walls around the wet area, and space is also reserved on the upper part of the partition for the total positive and negative copper bars and the liquid outlet pipe to pass through. The immersion liquid has a buffer area of ​​the dry area between the wet area of ​​the battery pack and the front wall of the battery pack. The immersion liquid may leak into the dry area in small amounts, but will not leak directly out of the battery pack.

[0044] like Figure 2 As shown, it also includes a fuse 11, CCS (integrated busbar) 12, a fixed end plate 13, an overflow partition 14, a through-wall terminal 15, a Bmu (battery management unit) 16, a liquid outlet pipe 17, a total negative copper bar 18, a total positive copper bar 19, and a module series copper bar 20. It can be understood that the above components are mainly used to cooperate with the immersion liquid-cooled battery pack to realize related functions. The structure of the overflow partition 14 is as follows Figure 7 shown.

[0045] In one embodiment of the present application, the Bmu is arranged in the dry area, and a maintenance window is opened on the box cover at a position directly above the Bmu.

[0046] The BMU is arranged in the dry area, and a maintenance window is provided on the box cover corresponding to the position just above the BMU, so as to facilitate the separate maintenance of the BMU and improve the convenience of maintenance.

[0047] It's important to note that the BMU (Battery Management Unit) is a core component of the Battery Management System (BMS), primarily used to monitor and manage the operating status of battery cells. It plays a key role in energy storage systems and new energy vehicles, ensuring the safety and efficiency of battery packs through data collection and balancing control.

[0048] In one embodiment of the present application, the immersion liquid is spread throughout the wet area, the immersion liquid-cooled battery pack is located in the wet area, and the immersion liquid is used to immerse the battery cells of the battery pack in the immersion liquid-cooled battery pack and the CCS and wiring harness connected to the battery cells.

[0049] The front wall of the battery pack features a hole for the connector to pass through. A sealing ring is placed between the connector and the hole to enhance the seal of the box. The connector connects to the main positive and negative copper bars, providing electrical connection between the battery pack and the outside world. A liquid outlet is located on the front of the battery pack and is connected to a liquid outlet pipe that extends from the dry area to the wet area to allow the circulating immersion fluid to flow out of the battery pack.

[0050] like Figure 5 As shown, it includes CCS (integrated busbar) 12 and fixed end plate 13, as well as battery cells 21, steel strips 22, and overflow partitions 23. A partition is provided in the battery pack to divide the area inside the battery pack into a wet area and a dry area. The partition is welded to the left and right box walls and the bottom of the box, and a layer of glue is applied to improve the sealing. The wet area is filled with immersion liquid and is located in the area where the battery cells are placed. It is used to immerse the battery cell module and the CCS connected to the battery cell, the module series copper bus, the collection harness, etc. The immersion liquid level is 2 cm higher than the battery cell pole. The dry area is provided with Bmu, the total positive and negative copper busbars, and the fuse. An opening is left above the partition for the total positive copper busbar, the total negative copper busbar, and the liquid outlet pipe to pass through. The lower edge of the opening is at least 2 cm higher than the free liquid surface of the immersion liquid.

[0051] In one embodiment of the present application, an explosion-proof valve 8 is provided on the upper cover of the battery pack.

[0052] like Figure 1 As shown, the battery pack's upper lid is equipped with the explosion-proof valve 8, which is used to discharge gas from the pack and balance the pressure inside and outside the battery pack when a battery cell experiences thermal runaway. The upper lid also features an innovative maintenance window 7, located directly above the BMU, to facilitate later maintenance of the BMU. The maintenance window is also connected to the upper lid via screws and rivet nuts, with a sealing gasket in between.

[0053] In one embodiment of the present application, gaps are reserved between the battery cells of the battery pack in the immersion liquid-cooled battery pack, gaps are reserved between the two outer rows of battery cells and the inner walls of the box on the left and right sides, and a gap is reserved between the battery pack and the lower surface of the upper box cover. The multiple reserved gaps serve as flow channels for the immersion liquid in the battery pack.

[0054] There are gaps between the cell modules, a certain distance between the two outer rows of modules and the inner walls of the left and right boxes, and a certain distance between the battery modules and the lower surface of the upper box cover, all of which serve as flow paths for the immersion fluid in the battery pack. There are gaps between the cell modules, a certain distance between the two outer rows of modules and the inner walls of the left and right boxes, and a certain distance between the battery modules and the lower surface of the upper box cover, all of which serve as flow paths for the immersion fluid in the battery pack.

[0055] In one embodiment of the present application, a liquid inlet is provided at the top of the bottom liquid cooling plate for the immersion liquid to flow into the liquid cooling plate flow channel; a plurality of through holes are provided at the tail of the bottom liquid cooling plate, and the plurality of through holes are located in the battery pack in an area between the inner wall of the back side of the battery pack and the end of the battery cell, for connecting the flow channel with the inner area of ​​the battery pack.

[0056] like Figure 6As shown, it includes a module fixing square tube 26 for fixing the battery pack of the battery pack. A liquid inlet is provided at the head of the liquid cooling plate for the immersion liquid to flow into the liquid cooling plate flow channel. A through hole is provided at the tail of the liquid cooling plate. The through hole is located inside the battery pack, in the area between the inner wall of the back of the battery pack and the end of the battery cell module, and is used to connect the flow channel with the area inside the battery pack. Specifically, the battery pack contains four modules, and a single module contains 12 battery cells. The battery cells are arranged along the thickness direction, with the large surfaces fitted together. The modules are fixed with end plates on both sides. The modules are bundled into groups with steel strips. A flow separator is provided between each pair of battery cells. On the one hand, it supports the battery cells, and on the other hand, it allows the immersion liquid to flow through the large surface of the battery cells to absorb the heat of the battery cells. Module fixing square tubes are provided on the bottom of the box at both ends of the battery module to fix the module position. Thermal conductive glue is provided between the battery cell module and the bottom of the box to enhance heat exchange. There is a through hole in the middle of the partition for the through-wall terminal to pass through. The through-wall terminal is used for the battery collection harness to pass through and connect to the BMU. A sealing ring is arranged between the through-wall terminal and the partition through hole to enhance the sealing performance of the partition. Figure 8 As shown, the liquid cooling plate includes through holes 25.

[0057] The immersed liquid-cooled battery pack case in the present embodiment includes an upper cover and a lower case. The lower case's surrounding walls are made using an aluminum extrusion process. The left, right, and rear walls have raised sections on the outside, while the insides are smooth. The upper edge of the outer wall has ample space for perforations. The upper cover is a flat aluminum plate, also perforated in corresponding areas. Screws and rivet nuts are used to secure and connect the upper and lower cases at the through-holes, forming a closed case. A sealing ring is placed at the junction of the upper cover and lower case to enhance the battery pack's sealing properties.

[0058] The liquid cooling plate is located between the four walls of the bottom of the lower box body. The four walls are connected to the liquid cooling plate by welding to form the lower box body. A circle of glue is applied at the junction of the bottom of the lower box body and the four walls, as well as at the junction between the walls, to improve the sealing of the box body.

[0059] In one embodiment of the present application, a thermally conductive adhesive layer is provided between the battery cells in the battery pack of the immersion liquid-cooled battery pack and the bottom of the box.

[0060] like Figure 6 As shown, thermal conductive glue is provided between the battery module and the bottom of the box to enhance heat exchange.

[0061] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. An immersion liquid-cooled battery pack, wherein: The immersion liquid-cooled battery pack includes: a bottom liquid cooling plate and an immersion liquid. The bottom liquid cooling plate is used to indirectly dissipate heat from the bottom of the battery cell of the battery pack in the immersion liquid-cooled battery pack through the immersion liquid, and the immersion liquid is used to directly dissipate heat from the immersion liquid-cooled battery pack.

2. The immersion liquid-cooled battery pack according to claim 1, wherein: After the immersion liquid flows to the tail of the bottom liquid cooling plate, it is sprayed into the battery pack through the through hole. The sprayed immersion liquid flows from the tail of the battery pack to the head of the battery pack, directly contacts the battery cells and takes away the heat of the battery cells. The liquid inlet and outlet of the immersion liquid-cooled battery pack are connected to an external liquid cooling unit, and the immersion liquid circulates through the operation of the pump of the external liquid cooling unit.

3. The immersion liquid-cooled battery pack according to claim 2, wherein: When the immersion liquid cools the battery core in the bottom liquid cooling plate and when the immersion liquid is sprayed out at the tail of the bottom liquid cooling plate, the temperature cascade effects generated by the two cancel each other out.

4. The immersion liquid-cooled battery pack according to claim 1, wherein: It also includes a flow separator for dividing the battery pack into a dry area and a wet area. The immersion liquid reserves the dry area as a buffer area between the wet area and the battery pack.

5. The immersion liquid-cooled battery pack according to claim 1, wherein: The BMU is arranged in the dry area, and a maintenance window is provided on the box cover corresponding to a position just above the BMU.

6. The immersion liquid-cooled battery pack according to claim 4, wherein: The immersion liquid is spread over the wet area, the immersion liquid-cooled battery pack is located in the wet area, and the immersion liquid is used to immerse the battery cells of the battery pack in the immersion liquid-cooled battery pack and the CCS and wiring harness connected to the battery cells.

7. The immersion liquid-cooled battery pack according to claim 1, wherein: An explosion-proof valve is provided on the upper cover of the battery pack.

8. The immersion liquid-cooled battery pack according to claim 1, wherein: In the immersion liquid-cooled battery pack, gaps are reserved between the battery cells of the battery pack, gaps are reserved between the two outer rows of battery cells and the inner walls of the box on the left and right sides, and gaps are reserved between the battery pack and the lower surface of the upper box cover. The multiple reserved gaps serve as flow channels for the immersion liquid in the battery pack.

9. The immersion liquid-cooled battery pack according to claim 1, wherein: A liquid inlet is provided at the top of the bottom liquid cooling plate for the immersion liquid to flow into the liquid cooling plate flow channel; a plurality of through holes are provided at the tail of the bottom liquid cooling plate, and the plurality of through holes are located in the area inside the battery pack between the inner wall of the back side of the battery pack and the end of the battery cell, for connecting the flow channel with the inner area of ​​the battery pack.

10. The immersion liquid-cooled battery pack according to claim 1, wherein: A thermally conductive adhesive layer is provided between the battery cells in the battery pack of the immersion liquid-cooled battery pack and the bottom of the box.

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