Submerged liquid-cooled battery pack

Abstract

The application discloses an immersed liquid-cooled battery pack, which comprises a bottom liquid-cooled plate and immersed liquid, wherein the bottom liquid-cooled plate is used for indirectly dissipating heat for the bottom of the battery cell of the battery pack in the immersed liquid-cooled battery pack, and the immersed liquid is used for directly dissipating heat for the immersed liquid-cooled battery pack. The heat dissipation mode of the bottom liquid-cooled plate indirectly liquid-cooled heat dissipation combined with the immersed liquid-cooled heat dissipation is adopted, so that efficient and uniform heat dissipation is provided for the battery cell.

Description

Technical Field

[0001] This application relates to the field of battery pack technology, and more particularly to an immersion liquid-cooled battery pack. Background Technology

[0002] Immersion cooling involves directly immersing the battery cell in a non-toxic, insulating, high thermal conductivity, and high specific heat capacity immersion liquid, allowing the battery cell to directly contact the immersion liquid for heat exchange, thereby improving the heat dissipation performance of the battery cell and the temperature uniformity between the battery cells.

[0003] Immersion liquid cooling, due to its direct heat exchange with the battery cells, offers higher heat transfer efficiency than indirect liquid cooling via liquid cooling plates. However, it places higher demands on flow channel design. If the flow organization of the immersion liquid is not optimized, localized flow dead zones can easily appear, causing localized heat accumulation and affecting the temperature characteristics of the battery pack. Furthermore, the flow channel design must also consider sealing and manufacturability. An overly complex flow channel design may not guarantee structural sealing at all points and can also lead to manufacturing difficulties and high costs.

[0004] Furthermore, considering that submersible liquid-cooled battery packs typically immerse all materials inside the battery pack (such as cells, wiring harnesses, BMUs, fuses, etc.) in the immersion liquid, this approach simplifies the design and fabrication of the battery pack casing, as all internal materials are located in the same area within the casing. Although this allows for a smaller battery pack size compared to semi-submersible designs, it requires openings on the front of the battery pack for the placement of through-wall terminals, connectors, liquid inlet / outlet ports, and immersion liquid inlets / outlets, making the immersion liquid prone to leakage. Utility Model Content

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

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

[0007] In a first aspect, embodiments of this application provide 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 to the bottom of the battery cells in the immersion liquid-cooled battery pack through the immersion liquid, and the immersion liquid is used to directly dissipate heat to the immersion liquid-cooled battery pack.

[0008] In some embodiments, 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 contacting the battery cells and carrying away the heat of the battery cells. The inlet and outlet of the immersion liquid-cooled battery pack are connected to an external liquid cooling unit, and the immersion liquid is circulated by the pump of the external liquid cooling unit.

[0009] In some embodiments, the temperature cascade effect generated by the immersion liquid cooling the battery cell on the bottom liquid cooling plate and the immersion liquid being sprayed out at the tail of the bottom liquid cooling plate cancels each other out.

[0010] In some embodiments, a flow-through baffle is further included to divide the battery pack into a dry area and a wet area, wherein 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 located in the dry area, and a maintenance window is provided on the cover directly above the Bmu.

[0012] In some embodiments, the immersion liquid covers 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, the CCS connected to the battery cells, and the wiring harness in the immersion liquid-cooled battery pack.

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

[0014] In some embodiments, gaps are reserved between the cells of the battery pack in the immersion liquid-cooled battery pack, gaps are reserved between the two rows of cells on the outer side 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. All of the reserved gaps serve as channels for the immersion liquid in the battery pack.

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

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

[0017] The at least one technical solution adopted in this application embodiment can achieve the following beneficial effects: The immersion liquid-cooled battery pack includes a bottom liquid cooling plate and an immersion liquid. The bottom liquid cooling plate is used for indirect heat dissipation of the bottom of the battery cells in the immersion liquid-cooled battery pack through the immersion liquid, and also for direct heat dissipation of the immersion liquid-cooled battery pack through the immersion liquid liquid. The combination of indirect liquid cooling through the bottom liquid cooling plate and immersion liquid cooling provides efficient and uniform heat dissipation for the battery cells. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0019] Figure 1 This is an isometric view of the submersible liquid-cooled battery pack in the embodiments of this application;

[0020] Figure 2 This is a top view of the submersible liquid-cooled battery pack in an embodiment of this application;

[0021] Figure 3 In the submersible liquid-cooled battery pack of the embodiments of this application Figure 1 The main view;

[0022] Figure 4 In the submersible liquid-cooled battery pack of the embodiments of this application Figure 1 Side view;

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

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

[0025] Figure 7 This is a schematic diagram of the flow separator of the submerged liquid-cooled battery pack in an embodiment of this application;

[0026] Figure 8 This is a schematic diagram of the liquid cooling plate of the immersion liquid-cooled battery pack in an embodiment of this application;

[0027] Figure 9 This is one of the schematic diagrams of the flow of immersion liquid in the immersion liquid-cooled battery pack in the embodiments of this 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 embodiments of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0031] This application provides an embodiment of an immersion liquid-cooled battery pack, such as Figure 1As shown, an isometric view of an immersion liquid-cooled battery pack according to an embodiment of this application is provided. The immersion liquid-cooled battery pack includes: a bottom liquid cooling plate 1 and an immersion liquid. The bottom liquid cooling plate 1 is used to indirectly dissipate heat to the bottom of the battery cells in the immersion liquid-cooled battery pack through the immersion liquid, and the immersion liquid is used to directly dissipate heat to the immersion liquid-cooled battery pack.

[0032] To distinguish between indirect and direct heat dissipation methods, in this embodiment, the "immersion liquid" in the bottom liquid cooling plate 1 serves as a carrier for indirect heat dissipation, indirectly cooling the bottom of the battery cells in the submerged liquid-cooled battery pack. In this embodiment, the "immersion liquid" is primarily used to immerse the submerged liquid-cooled battery pack for direct heat dissipation. It is understood that the "immersion liquid" is an oily substance, mostly a synthetic oil liquid, and is not specifically limited in this embodiment.

[0033] like Figure 1 and Figure 3 As shown, specifically, the heat dissipation method of the submerged liquid-cooled battery pack in this embodiment is a composite heat dissipation method, including indirect heat dissipation via the bottom liquid cooling plate and direct heat dissipation via the submerged liquid. The submerged liquid flows into the liquid cooling plate channel through the liquid cooling plate inlet. Through the channel design of the liquid cooling plate, the submerged liquid is evenly distributed to the bottom of each cell module to dissipate heat at the bottom of the cell. After flowing to the tail of the liquid cooling plate, the submerged liquid is sprayed into the battery pack through the through holes. The sprayed submerged liquid flows from the tail of the battery pack to the head of the battery pack, directly contacting the cells and carrying away the heat from the cells, and then flows out through the outlet on the box wall. The inlet and outlet of the battery pack are connected to an external liquid cooling unit, and the pump of the external liquid cooling unit promotes the circulation of the submerged liquid. Figure 9 and Figure 10 As shown.

[0034] When the immersion fluid is used to directly dissipate heat from the submerged liquid-cooled battery pack, there are two types of immersion fluid cooling: circulating and static. The circulating type requires an external dedicated liquid cooler, where a pump in the immersion fluid circuit drives the fluid circulation, and the cooling circuit within the cooler removes the heat absorbed by the fluid. The static type involves a stationary immersion fluid, where the battery cells are simply immersed in it; this method usually requires combination with other heat dissipation methods. Another major advantage of using immersion liquid cooling is that when a battery cell experiences thermal runaway, the immersion fluid can quickly absorb and remove the heat. Simultaneously, because the immersion fluid is in direct contact with the pack's internal materials, it needs to have good compatibility and insulation properties.

[0035] The immersion liquid-cooled battery pack in this application embodiment has technical advantages such as high-efficiency heat dissipation, easy maintenance, and good sealing effect. Furthermore, the heat dissipation scheme, which combines indirect liquid cooling with immersion liquid cooling through the bottom liquid cooling plate, can provide efficient and uniform heat dissipation for the battery cells in the battery pack.

[0036] In one embodiment of this application, 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, and directly contacts the battery cell to remove the heat of the battery cell. The inlet 4 and outlet 5 of the immersion liquid-cooled battery pack are connected to an external liquid cooling unit, and the immersion liquid is circulated by the pump of the external liquid cooling unit.

[0037] like Figure 1 and Figure 3 As shown, the liquid inlet 4 is located on the liquid cooling plate, and the liquid outlet 5 is located on the lower casing wall. The lower casing 2 and the casing 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 to external devices, a maintenance window 7 providing an inspection window, an explosion-proof valve 8 with explosion-proof function, screws 9 for fixing the cover 3, and lifting lugs 24 for easy lifting and movement. Lifting lugs 24 are provided on both sides of the liquid cooling plate for lifting the battery pack. The flow path is as follows... Figure 9 and Figure 10 As shown.

[0038] like Figure 4 As shown, it also includes a rivet nut 10 and a lifting lug 24.

[0039] It is important to note that the compatibility of the materials inside the tank with the immersion liquid should be a priority.

[0040] In one embodiment of this application, the temperature cascade effect generated by the immersion liquid cooling the battery cell when the immersion liquid is cooled by the bottom liquid cooling plate 1 and the immersion liquid being sprayed out from the tail of the bottom liquid cooling plate 1 cancels each other out.

[0041] Specifically, the immersion fluid flows within the liquid cooling plate from the head to the tail of the battery pack, resulting in lower temperatures for the cells near the head and higher temperatures for the cells near the tail. After being sprayed out, the immersion fluid flows from the tail to the head, causing the cells near the tail to remain cooler and those near the head to remain warmer, thus mitigating the temperature cascading effect. These two processes create a "temperature cascading effect" that cancels each other out. The immersion fluid cooling the cells on the bottom liquid cooling plate 1 and the immersion fluid being sprayed out at the tail of the bottom liquid cooling plate 1 create a canceling "temperature cascading effect."

[0042] In one embodiment of this application, a flow-through baffle is further included to divide the battery pack into a dry area and a wet area, wherein 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 flow-through baffle 14 is to divide the battery pack into a dry area and a wet area, and to provide a buffer zone between the wet area and the battery pack for the immersion liquid in the dry area. By adding the flow-through baffle 14 inside the battery pack, the battery pack is divided into dry and wet areas. The dry area is located at the head of the battery pack, and a hole for connectors to pass through is opened on the front wall of the battery pack, as well as a battery pack liquid outlet. Preferably, only the baffle on the surrounding walls of the wet area needs to have holes for through-wall terminals to pass through. Space is also left at the top of the baffle for the main positive and negative copper busbars and the liquid outlet pipe to pass through. The immersion liquid has a buffer zone between the wet area and the front wall of the battery pack, and a small amount of immersion liquid may leak into the dry area, but it will not leak directly outside the battery pack.

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

[0045] In one embodiment of this application, the Bmu is disposed in the dry area, and a maintenance window is provided on the cover directly above the Bmu.

[0046] The Bmu is located in the dry area, and a maintenance window is provided on the cover directly above the Bmu, which facilitates individual maintenance of the Bmu and improves the convenience of maintenance.

[0047] It is important to note that the Bmu (Battery Management Unit) is the core component of the Battery Management System (BMS), primarily used to monitor and manage the operating status of individual battery cells. It plays a crucial role in energy storage systems, new energy vehicles, and other fields, ensuring the safety and efficiency of the battery pack through functions such as data acquisition and equalization control.

[0048] In one embodiment of this application, the immersion liquid covers 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, the CCS connected to the battery cells, and the wiring harness in the immersion liquid-cooled battery pack.

[0049] The front wall of the battery pack has openings for connectors to pass through. A sealing ring is placed between the connector and the opening to enhance the pack's airtightness. The connectors connect to the main positive and negative copper busbars for electrical connection between the battery pack and the external environment. A liquid outlet is located on the front of the battery pack, connected to a liquid outlet pipe that extends from the dry area to the wet area, allowing circulating immersion liquid to flow out from inside the battery pack.

[0050] like Figure 5 As shown, the battery pack includes a CCS (integrated busbar) 12 and a fixed end plate 13, as well as battery cells 21, steel strips 22, and a current-carrying separator 23. The battery pack contains separators that divide the internal area into a wet zone and a dry zone. The separators are welded to the left and right side walls and the bottom of the pack, and a layer of adhesive is applied to improve sealing. The wet zone, located in the area where the battery cells are placed, is filled with immersion fluid and is used to immerse the battery cell modules and the CCS, module series copper busbars, and data acquisition harnesses connected to the cells. The immersion fluid level is 2 cm higher than the battery cell terminals. The dry zone contains a Bmu (Battery Unit), main positive and main negative copper busbars, and fuses. An opening is provided above the separator for the main positive and main negative copper busbars and the outlet pipe to pass through; the lower edge of the opening is at least 2 cm above the free surface of the immersion fluid.

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

[0052] like Figure 1 As shown, the explosion-proof valve 8 is installed on the battery pack top cover, which is used to release gas inside the pack and balance the air pressure inside and outside the battery pack when thermal runaway occurs in the battery cell. The top cover is innovatively equipped with a maintenance window 7, located directly above the Bmu, which facilitates the separate maintenance of the Bmu in the future. The maintenance window is also connected to the top cover by screws and rivet nuts, and a sealing gasket is provided in the middle.

[0053] In one embodiment of this application, gaps are reserved between the cells of the battery pack in the immersion liquid-cooled battery pack, gaps are reserved between the two rows of cells on the outer side 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. All of the reserved gaps serve as channels for the immersion liquid in the battery pack.

[0054] Gaps are left between the battery cell modules, and a certain distance is maintained between the two outer rows of modules and the inner walls of the left and right side boxes. A certain distance is also maintained between the battery modules and the lower surface of the upper box cover; all these serve as channels for the immersion liquid within the battery pack.

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

[0056] like Figure 6As shown, the battery pack includes a module fixing square tube 26 for fixing the battery pack. The head of the liquid cooling plate has an inlet for the immersion liquid to flow into the liquid cooling plate channel. The tail of the liquid cooling plate has a through hole located inside the battery pack, in the area between the inner wall of the battery pack's back and the end of the cell module, connecting the channel to the internal area of ​​the battery pack. Specifically, the battery pack contains four modules, each containing 12 cells arranged along the thickness direction with their surfaces largely attached. End plates on both sides of the module fix it, and the modules are bundled together by steel straps. Flow baffles are placed between pairs of cells, providing support and allowing the immersion liquid to flow over the large surfaces of the cells to absorb heat. Module fixing square tubes are located at both ends of the battery module on the bottom of the casing for fixing the module position. Thermally conductive adhesive is applied between the cell module and the bottom of the casing to enhance heat exchange. The partition has a through hole in the middle for a through-wall terminal to pass through. The through-wall terminal is used for the battery cell acquisition harness to pass through and connect to the Bmu. A sealing ring is arranged between the through-wall terminal and the through hole in the partition to enhance the sealing performance of the partition. Figure 8 As shown, this includes a through-hole 25 for the liquid cooling plate.

[0057] The submersible liquid-cooled battery pack enclosure in this embodiment includes an upper cover and a lower enclosure. The lower enclosure is made of aluminum extrusion, with raised sections on the outer sides of the left, right, and rear walls. The inner side of the enclosure wall is smooth, and there is sufficient area for perforation along the upper edge of the outer wall. The upper cover is a flat aluminum plate, also with perforations in the corresponding area. The upper cover and lower enclosure are fixed and connected at the through-hole positions using screws and rivet nuts to form a closed enclosure. A sealing ring is provided at the connection between the upper cover and the lower enclosure to enhance the battery pack's sealing performance.

[0058] The liquid cooling plate serves as the bottom of the lower enclosure. The four sides of the enclosure are connected to the liquid cooling plate by welding to form the lower enclosure. At the junction of the bottom of the lower enclosure and the four sides of the enclosure, as well as at the junction of the enclosure walls, a ring of glue is applied to seal the enclosure and improve its airtightness.

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

[0060] like Figure 6 As shown, thermally conductive adhesive is placed between the battery cell module and the bottom of the casing to enhance heat exchange.

[0061] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this 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 to the bottom of the battery cells in the immersion liquid-cooled battery pack through the immersion liquid, and the immersion liquid is used to directly dissipate heat to the immersion liquid-cooled battery pack.

2. The immersion liquid-cooled battery pack as described in 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 contacting the battery cells and carrying away the heat of the battery cells. The inlet and outlet of the immersion liquid-cooled battery pack are connected to an external liquid cooling unit, and the immersion liquid is circulated by the pump of the external liquid cooling unit.

3. The immersion liquid-cooled battery pack as described in claim 2, wherein, The temperature cascade effect generated by the immersion liquid cooling the battery cell at the bottom liquid cooling plate and the immersion liquid being sprayed out at the tail of the bottom liquid cooling plate cancels each other out.

4. The immersion liquid-cooled battery pack as described in claim 1, wherein, It also includes a flow-through baffle to divide the battery pack into a dry area and a wet area, wherein the immersion liquid reserves the dry area as a buffer zone between the wet area and the battery pack.

5. The immersion liquid-cooled battery pack as described in claim 1, wherein, The Bmu is located in the dry area, and a maintenance window is provided on the cover directly above the Bmu.

6. The immersion liquid-cooled battery pack as described in claim 4, wherein, The immersion liquid covers the wet area, and the immersion liquid-cooled battery pack is located in the wet area. The immersion liquid is used to immerse the battery cells, CCS connected to the battery cells, and wiring harness in the immersion liquid-cooled battery pack.

7. The immersion liquid-cooled battery pack as described in claim 1, wherein, An explosion-proof valve is installed on the top cover of the battery pack.

8. The immersion liquid-cooled battery pack as described in claim 1, wherein, In the immersion liquid-cooled battery pack, gaps are reserved between the battery cells, gaps are reserved between the two rows of cells on the outer side 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. All of these reserved gaps serve as channels for the immersion liquid inside the battery pack.

9. The immersion liquid-cooled battery pack as described in claim 1, wherein, The bottom liquid cooling plate has a liquid inlet at its top for the immersion liquid to flow into the liquid cooling plate channel; the bottom liquid cooling plate has multiple through holes at its tail, which are located in the area between the inner wall of the back of the battery pack and the end of the battery cell, and are used to connect the channel to the inner area of ​​the battery pack.

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

Images