A fully immersed liquid-cooled battery pack and its internal gas-liquid relief device

Abstract

The application discloses a full-submersion liquid-cooled battery pack and an internal gas-liquid relief device thereof, which comprises a shell, a pressure regulating valve rod and a pressing mechanism. One end of the shell is provided with an internal circulating liquid communication bin, and the other end is provided with an external circulating liquid communication bin. A plurality of relief holes are formed in the wall surface of the internal circulating liquid communication bin. The pressure regulating valve rod is arranged in the shell in the axial direction, and separates the internal circulating liquid communication bin and the external circulating liquid communication bin. The internal end of the pressure regulating valve rod is in communication with the internal circulating liquid of the battery pack through the internal circulating liquid communication bin, and the external end is in communication with the external circulating liquid of the battery pack through the external circulating liquid communication bin. The pressing mechanism is arranged between the external end of the pressure regulating valve rod and the base of the external circulating liquid communication bin in the axial direction. The device designed in the application can adjust the opening pressure of the gas-liquid relief device in real time based on the internal pressure change of the battery pack, and can rapidly relieve the internal pressure after thermal runaway while ensuring the sealing property of the battery pack.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery, more particularly, to a full-immersion liquid-cooled battery pack and an internal gas-liquid relief device thereof. BACKGROUND

[0002] In recent years, lithium batteries have been widely used in electric transportation and energy storage due to their excellent performance and increasingly low cost. However, due to the properties of lithium batteries, thermal runaway accidents may occur after misuse. In a lithium battery system, the damage caused by a single lithium battery cell after thermal runaway is limited, but the thermal runaway cell will transfer heat to the surrounding cells through thermal conduction, thermal convection and thermal radiation. Once the thermal runaway threshold of the adjacent cells is exceeded, a thermal runaway spread accident will occur in the battery system. To prevent the occurrence of thermal spread accidents in the battery system, the main methods are to reduce the heat production of the runaway cell, enhance the thermal insulation between cells, and improve the heat dissipation of the cells. After the lithium battery experiences thermal runaway, it is important to quickly direct the released heat out of the system to prevent the spread of heat between cells. Compared with the current mainstream indirect liquid cooling scheme, immersion cooling significantly enhances the heat dissipation power through the latent heat of vaporization of liquid-gas phase change and the two-phase turbulent flow generated thereby. In a full-immersion liquid-cooled battery pack, each surface of the battery pack is uniformly immersed in the cooling circulating liquid, which can provide better temperature consistency and reduce the contact thermal resistance between the battery pack and the cooling medium. Therefore, the introduction of immersion cooling technology into the battery system is of great significance to enhance the overall thermal management performance of the system.

[0003] However, there is no good solution to how to control the full-immersion liquid-cooled battery pack to prevent leakage while quickly relieving pressure inside the battery pack in the event of thermal runaway. Most existing immersion cooling systems still rely on explosion-proof valves for pressure relief design, but the opening pressure of the explosion-proof valve is generally a certain value. However, the internal pressure of the immersion cooling system changes over time during operation, which poses a great challenge to the selection of the opening pressure of the explosion-proof valve: a redundant design will cause a delay in opening after thermal runaway, and an insufficient design will result in battery pack leakage. Therefore, the development of a variable-pressure gas-liquid relief device is of great significance to the promotion of full-immersion liquid-cooled battery systems. SUMMARY

[0004] Due to the problems of the prior art, the present application provides a full-immersion liquid-cooled battery pack and an internal gas-liquid relief device thereof, which can adapt to variable pressure adjustment while ensuring the sealing of the battery pack and quickly relieving pressure inside the battery pack after thermal runaway.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides an internal gas-liquid relief device of a full-immersion liquid-cooled battery pack, comprising:

[0006] The shell is provided with an internal circulation liquid communication bin at one end and an external circulation liquid communication bin at the other end; a plurality of relief holes are formed in the wall of the internal circulation liquid communication bin;

[0007] A pressure regulating valve rod is arranged in the shell in the axial direction and separates the internal circulation liquid communication bin and the external circulation liquid communication bin; the internal end of the pressure regulating valve rod is in communication with the internal circulation liquid of the battery pack through the internal circulation liquid communication bin, and the external end is in communication with the external circulation liquid of the battery pack through the external circulation liquid communication bin;

[0008] A pressing mechanism is arranged in the axial direction between the external end of the pressure regulating valve rod and the base of the external circulation liquid communication bin;

[0009] When the fully-submerged liquid-cooled battery pack is in normal operation, the internal pressure of the battery pack is in a normal state, and under the action of the pre-tightening force of the pressing mechanism and the external circulation liquid pressure, the pressure regulating valve rod blocks the communication between the relief holes and the internal circulation liquid of the battery pack;

[0010] When the fully-submerged liquid-cooled battery pack is in or close to thermal runaway, the internal pressure of the battery pack abnormally increases, the internal end pressure is greater than the external end pressure, and the pressure regulating valve rod moves towards the external circulation liquid communication bin, so that the gas-liquid in the battery pack is discharged through the relief holes.

[0011] Since the flow and pressure of the cooling liquid inside and outside the battery will change with the working condition of the battery, a single opening pressure explosion-proof valve is easy to cause leakage of the cooling liquid or to increase the probability of heat spread due to untimely opening. The gas-liquid discharge device of the present application can realize closing or opening through the pressure difference between the internal end and the external end, and can dynamically adjust the opening pressure of the device according to the changes of the external circulation liquid pressure of the battery pack and the internal pressure of the battery pack, thereby avoiding the leakage of the cooling liquid caused by the single opening pressure of the explosion-proof valve or increasing the probability of heat spread due to untimely opening.

[0012] Further, the relief holes are arranged in the circumferential, radial or fixed direction of the internal circulation liquid communication bin to meet the needs of different application environments.

[0013] Further, the internal circulation liquid communication bin and / or the internal wall of the external circulation liquid communication bin are provided with a limiting step of the pressure regulating valve rod to ensure that the rod-shaped regulating valve is in a suitable position and to ensure that the external circulation pressure seals the internal end.

[0014] Further, the external end surface of the internal circulation liquid communication bin is provided with a first connecting flange.

[0015] Further, the base and the external circulation liquid communication bin are integrally formed.

[0016] Further, the internal end surface of the base is detachably fixedly connected with the external circulation liquid communication bin through a second connecting flange.

[0017] Further, the pressing mechanism is a spring.

[0018] In a second aspect, the application provides a fully immersed liquid-cooled battery pack, comprising a battery pack, an internal cooling circulating liquid in which the battery pack is fully immersed, characterized in that it further comprises an internal gas-liquid relief device as described above; the internal circulating liquid communication bin of the internal gas-liquid relief device is connected to the internal cooling circulating liquid pipeline, and the external circulating liquid communication bin is connected to the circulating liquid water inlet.

[0019] Compared with the prior art, the application has the following technical effects:

[0020] (1) The gas-liquid relief device of the application can dynamically adjust the opening pressure of the device according to the changes in the external circulating liquid pressure of the battery pack and the internal pressure of the battery pack, thereby avoiding the leakage of the cooling liquid caused by the false opening of the explosion-proof valve due to a single opening pressure or the increase in the probability of heat spread caused by untimely opening.

[0021] (2) The gas-liquid relief device of the application is reusable, and even if the internal circulating cooling system of the battery pack fails after thermal runaway, the gas-liquid relief device can still be normally closed under the action of the pressing mechanism.

[0022] (3) The gas-liquid relief device of the application has a simple structure, is easy to process, has no special-shaped structural parts, and is low in cost, and can be widely applied to immersed cooling battery systems of various systems and spatial structures. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application and its features, shapes and advantages will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings. The same reference numbers in all the drawings indicate the same parts. The drawings are not drawn to scale, and the emphasis is on illustrating the main idea of the application.

[0024] Figure 1 FIG. 1 is a perspective view of the gas-liquid relief device in an embodiment of the application.

[0025] Figure 2 FIG. 2 is an exploded view of the gas-liquid relief device in an embodiment of the application.

[0026] Figure 3 FIG. 3 is an axial sectional view of the gas-liquid relief device in an embodiment of the application in a normal working state of the battery pack.

[0027] Figure 4 FIG. 4 is an axial sectional view of the gas-liquid relief device in an embodiment of the application in a thermal runaway state of the battery pack.

[0028] Figure 5 FIG. 5 is a schematic view of the connection structure of the fully immersed liquid-cooled battery pack and the gas-liquid relief device in another embodiment of the application.

[0029] Figure 6 For Figure 5 Enlarged view of A in the middle.

[0030] In the drawings: 1, housing; 11, internal circulating liquid communication bin; 12, external circulating liquid communication bin; 13, discharge hole; 121, base; 111, first connecting flange; 122, second connecting flange;

[0031] 2, pressure regulating valve stem; 21, internal end; 22, external end; 23, limiting step;

[0032] 3, pressing mechanism;

[0033] 4, battery pack; 5, connecting pipeline; 6, circulating liquid water inlet; 7, water outlet. DETAILED DESCRIPTION

[0034] The application will be further described below in conjunction with the drawings and specific examples, but not as a limitation of the application.

[0035] In the description of the present application, unless otherwise explicitly specified and limited, the terms "provided", "provided with", "connected" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; the mode can be welding, or threaded connection; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] It should be understood that the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features.

[0037] Example 1

[0038] Referring to Figures 1 to 3 , the present embodiment provides an internal gas-liquid discharge device for a full-immersion liquid-cooled battery pack, comprising: a housing 1, a pressure regulating valve stem 2, and a pressing mechanism 3.

[0039] The housing 1 is provided with an internal circulating liquid communication bin 11 at one end and an external circulating liquid communication bin 12 at the other end; a plurality of discharge holes 13 are formed in the wall surface of the internal circulating liquid communication bin 11. The discharge holes 13 can be arranged along the circumferential direction, radial direction or fixed direction of the internal circulating liquid communication bin 11 to meet the needs of different application environments.

[0040] The pressure regulating valve stem 2 is arranged in the casing 1 in the axial direction, and separates the internal circulation liquid communication chamber 11 and the external circulation liquid communication chamber 12. The internal end 21 of the pressure regulating valve stem 2 is in communication with the internal circulation liquid of the battery pack through the internal circulation liquid communication chamber 11, and the external end 22 is in communication with the external circulation liquid of the battery pack through the external circulation liquid communication chamber 12. The pressure of the internal end 21 is equal to the internal pressure of the battery pack. When the battery is normally working, the internal pressure of the battery pack is equal to the internal circulation liquid pressure at the connection point. Due to the pressure loss along the circulation flow and the local pressure loss of the internal cooling liquid, the pressure at the circulation liquid inlet will be greater than the internal pressure of the battery pack. In the normal working state, the pressure of the external end 22 is always greater than that of the internal end 21. Through the pressure difference between the internal end 21 and the external end 22, the axial movement of the valve stem is realized.

[0041] The pressing mechanism 3 is arranged in the axial direction between the external end 22 of the pressure regulating valve stem 2 and the base 121 of the external circulation liquid communication chamber 12. The base 121 is integrally formed with the external circulation liquid communication chamber 12 or is detachably fixedly connected. The pressing mechanism 3 can be a spring or other elastic body. The pressing mechanism 3 ensures that the pressure at the external circulation liquid communication chamber 12 is always greater than the internal pressure of the battery pack in the case of normal circulation or storage of the battery, and the internal gas-liquid relief device will not be mistakenly opened.

[0042] Referring to Figure 3 When the fully immersed liquid-cooled battery pack is normally working, the internal pressure of the battery pack is in a normal state. Under the combined action of the pre-tightening force of the pressing mechanism 3 and the external circulation liquid pressure, the pressure regulating valve stem 2 blocks the communication between the relief hole 13 and the internal circulation liquid of the battery pack, and prevents the internal circulation liquid of the battery pack from leaking. Since the flow and pressure of the cooling liquid will change with the working condition, the internal pressure of the battery pack will also change, so the pressure difference between the two ends of the pressure regulating valve stem 2 will change according to the running condition of the battery pack, and a single opening pressure relief valve cannot well cope with such an environment.

[0043] Referring to Figure 4When the full-submersion liquid-cooled battery pack occurs or approaches thermal runaway (for example, a certain battery in the battery pack occurs thermal runaway), the internal pressure of the battery pack abnormally increases (for example, a series of chain reactions of heat and gas production occur in the battery, and the internal pressure of the battery pack rises sharply), the internal end 21 pressure is greater than the external end 22 pressure, the pressure regulating valve rod 2 moves to the external circulation liquid communication warehouse 12 direction, so that the compression mechanism 3 is in a compressed state, and the battery pack internal gas-liquid is discharged through the discharge hole 13. It can be seen that the size of the internal pressure of the battery pack determines the size of the opening size of the discharge hole. After the thermal runaway battery in the battery pack is controlled, the gas-liquid discharge device can still recover to the closed state under the action of the compression mechanism 3, preventing the internal cooling efficiency from decreasing due to the leakage of the battery pack internal cooling liquid.

[0044] As a preferred embodiment, referring to Figure 3 , the internal circulation liquid communication warehouse 11 and / or the outer circulation liquid communication warehouse 12 is provided with a limiting step 23 of the pressure regulating valve rod 2, so as to ensure that the rod-shaped regulating valve is in a proper position and ensure that the external circulation pressure is sealed in the internal end.

[0045] As a preferred embodiment, the internal circulation liquid communication warehouse 11 and the outer circulation liquid communication warehouse 12 are cylindrical, and the inner diameter of the internal circulation liquid communication warehouse 11 is smaller than that of the outer circulation liquid communication warehouse 12.

[0046] As a preferred embodiment, referring to Figure 2 , the inner end surface of the base 121 is detachably fixedly connected with the outer circulation liquid communication warehouse 12 through the second connecting flange 122.

[0047] From the above description, it can be known that the internal gas-liquid discharge device of the embodiment utilizes the differential pressure evolution law of the full-submersion liquid-cooled battery pack circulation system, dynamically adjusts the opening pressure of the internal gas-liquid discharge device of the battery pack according to the change of the internal pressure of the battery pack and the external cooling liquid circulation pipeline of the battery pack, avoids the cooling liquid leakage caused by the single opening pressure of the explosion-proof valve or the increase of the thermal spread probability caused by the untimely opening. The internal gas-liquid discharge device has a wide application range and can be widely applied to various systems and space structures of the submerged cooling battery system.

[0048] Embodiment 2

[0049] Referring to Figure 5 , the embodiment provides a full-submersion liquid-cooled battery pack 4, which comprises a battery pack, an internal cooling circulation liquid completely immersed in the battery pack, and an internal gas-liquid discharge device as described in embodiment 1. The internal circulation liquid communication warehouse 11 of the internal gas-liquid discharge device is connected with the internal cooling circulation liquid pipeline, and the outer circulation liquid communication warehouse 12 is connected with the circulation liquid inlet 6 through the connecting pipeline 5.

[0050] As a preferred embodiment, referring to Figure 1And Figure 6 The outer end surface of the internal circulating liquid communication bin 11 is provided with a first connecting flange 111. The internal circulating liquid communication bin 11 is connected to the internal cooling circulating liquid pipeline of the battery pack through the first connecting flange 111.

[0051] During normal operation, the circulating liquid fluid will cause the pressure at the circulating liquid water inlet 6 to be higher than the pressure at the water outlet 7 due to the pressure loss along the pipeline and the local pressure loss, that is, the pressure at the circulating liquid water inlet 6 should be the highest in the fully immersed battery pack, and connecting the external circulating liquid communication bin 12 to the circulating liquid water inlet 6 can ensure that the pressure of the external cooling circulating liquid of the battery pack plus the pressure of the pressing mechanism can press the internal end 21, and leakage will not occur.

[0052] In summary, the application provides a fully immersed liquid-cooled battery pack and an internal gas-liquid relief device thereof, which comprises: a shell, a pressure regulating valve rod, and a pressing mechanism. One end of the shell is provided with an internal circulating liquid communication bin, and the other end is provided with an external circulating liquid communication bin. A plurality of relief holes are formed in the wall surface of the internal circulating liquid communication bin. The pressure regulating valve rod is arranged in the shell in the axial direction and separates the internal circulating liquid communication bin and the external circulating liquid communication bin. The internal end of the pressure regulating valve rod is in communication with the internal circulating liquid of the battery pack through the internal circulating liquid communication bin, and the external end thereof is in communication with the external circulating liquid of the battery pack through the external circulating liquid communication bin. The pressing mechanism is arranged in the axial direction between the external end of the pressure regulating valve rod and the base of the external circulating liquid communication bin. The application can adapt to the opening and closing of the variable pressure regulating valve rod in the battery, and can ensure the sealing of the battery pack and rapidly relieve the internal pressure after thermal runaway.

[0053] Those skilled in the art should understand that those skilled in the art can realize the variant examples in combination with the prior art and the above-mentioned embodiments, which are not described here. Such variant examples do not affect the essential content of the application, and are not described here.

[0054] The preferred embodiments of the application are described above. It should be understood that the application is not limited to the above specific embodiments, and the systems and structures not described in detail should be understood as being implemented in the ordinary way in the art; any person skilled in the art can make many possible changes and modifications to the technical solutions of the application by using the disclosed methods and technical contents without departing from the scope of the technical solutions of the application, or modify equivalent embodiments of equivalent changes, which do not affect the essential content of the application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the application, without departing from the content of the technical solutions of the application, all still belong to the scope of protection of the technical solutions of the application.

Claims

1. An internal gas-liquid venting device for a fully submerged liquid-cooled battery pack, characterized in that, include: The outer shell (1) has an internal circulating fluid communication chamber (11) at one end and an external circulating fluid communication chamber (12) at the other end; the wall of the internal circulating fluid communication chamber (11) has several drainage holes (13). A pressure regulating valve stem (2) is axially disposed inside the housing (1), separating the internal circulating fluid communication chamber (11) and the external circulating fluid communication chamber (12); the internal end (21) of the pressure regulating valve stem (2) is connected to the internal circulating fluid of the battery pack through the internal circulating fluid communication chamber (11), and its external end (22) is connected to the external circulating fluid of the battery pack through the external circulating fluid communication chamber (12); The clamping mechanism (3) is axially disposed between the outer end (22) of the pressure regulating valve stem (2) and the base (121) of the external circulating fluid communication chamber (12); When the fully submerged liquid-cooled battery pack is working normally, the internal pressure of the battery pack is in a normal state. Under the action of the pre-tightening force of the clamping mechanism (3) and the external circulating liquid pressure, the pressure regulating valve rod (2) blocks the connection between the vent hole (13) and the circulating liquid inside the battery pack. When a fully submerged liquid-cooled battery pack experiences or is close to thermal runaway, the internal pressure of the battery pack increases abnormally. The pressure at the internal end (21) is greater than the pressure at the external end (22). The pressure regulating valve rod (2) moves toward the external circulating liquid communication chamber (12), causing the gas and liquid inside the battery pack to be released through the vent hole (13).

2. The internal gas-liquid venting device for the fully submerged liquid-cooled battery pack according to claim 1, characterized in that, The vent (13) is arranged along the circumferential, radial or fixed direction of the internal circulating fluid communication chamber (11).

3. The internal gas-liquid venting device for the fully submerged liquid-cooled battery pack according to claim 1, characterized in that, The inner walls of the internal circulating fluid communication chamber (11) and / or the external circulating fluid communication chamber (12) are provided with limiting steps (23) for the pressure regulating valve stem (2).

4. The internal gas-liquid venting device for the fully submerged liquid-cooled battery pack according to claim 1, characterized in that, The outer end face of the internal circulating fluid communication chamber (11) is provided with a first connecting flange (111).

5. The internal gas-liquid venting device for the fully submerged liquid-cooled battery pack according to claim 1, characterized in that, The inner end face of the base (121) is detachably fixedly connected to the external circulating fluid communication chamber (12) via the second connecting flange (122).

6. The internal gas-liquid venting device for the fully submerged liquid-cooled battery pack according to claim 1, characterized in that, The clamping mechanism (3) is a spring.

7. A fully submersible liquid-cooled battery pack, comprising a battery pack, wherein the interior of the battery pack is a fully submersible structure, characterized in that, It also includes an internal gas-liquid venting device as described in any one of claims 1 to 6; the internal circulating liquid communication chamber (11) of the internal gas-liquid venting device is connected to the internal space of the battery pack, and the pressure at its end is equal to the internal pressure of the battery pack at the connection point, and the external circulating liquid communication chamber (12) is connected to the circulating liquid inlet (6).

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