Fully-immersed liquid-cooled battery pack and internal gas-liquid discharging device thereof

Abstract

The invention discloses a fully-immersed liquid-cooled battery pack and an internal gas-liquid discharging device thereof. The fully-immersed liquid-cooled battery pack 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 discharge 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 divides the internal circulating liquid communication bin and the external circulating liquid communication bin. The internal end of the pressure regulating valve rod is communicated with internal circulating liquid of the battery pack through the internal circulating liquid communicating bin, and the external end of the pressure regulating valve rod is communicated with external circulating liquid of the battery pack through the external circulating liquid communicating bin; the pressing mechanism is arranged between the outer end of the pressure adjusting valve rod and the base of the outer circulating liquid communication bin in the axial direction. According to the device designed by the invention, the opening pressure of the gas-liquid discharge device can be adjusted in real time based on the internal pressure change of the battery pack, and internal quick pressure relief can be realized after thermal runaway while the sealing performance of the battery pack is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and more specifically, to a fully immersed liquid-cooled battery pack and an internal gas-liquid discharge device thereof. Background Art

[0002] In recent years, lithium batteries have been widely used in the fields of electric transportation and energy storage due to their excellent performance and increasingly low cost. However, limited by the properties of lithium batteries themselves, thermal runaway accidents may occur after lithium batteries are abused. In a lithium battery system, the harm caused by a single lithium battery cell in thermal runaway is limited, but the thermal runaway cell will transfer heat to the surrounding cells through heat conduction, heat convection, and heat radiation. Once the thermal runaway threshold of adjacent cells is exceeded, a thermal runaway spread accident will occur inside the battery system. Suppressing the occurrence of thermal runaway accidents in the battery system is mainly achieved by reducing the heat generation of runaway cells, enhancing the heat insulation between cells, and strengthening the heat dissipation of cells. After a lithium battery undergoes thermal runaway, quickly discharging the released heat is of great significance for suppressing the occurrence of thermal spread between cells. Compared with the current mainstream indirect liquid-cooling heat dissipation scheme, immersion cooling significantly enhances the heat dissipation power through the latent heat of vaporization of liquid-gas phase change and the resulting two-phase turbulence. Inside a fully immersed liquid-cooled battery pack, all sides of the battery pack are evenly 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, introducing immersion cooling technology into the battery system is of great significance for enhancing the overall thermal management performance of the system.

[0003] However, there is no good solution for how to control the fully immersed liquid-cooled battery pack from leaking and quickly relieve the internal pressure in the thermal runaway scenario. Most existing immersion cooling systems still rely on explosion-proof valves for explosion relief design. However, the opening pressure of the explosion-proof valve is generally a certain value, but the internal pressure of the battery pack in the immersion cooling system changes over time during operation, which will pose a great challenge to the selection of the opening pressure of the explosion-proof valve: redundant design will cause delayed opening after thermal runaway, and insufficient design will lead to liquid leakage of the battery pack. Therefore, developing a variable-pressure gas-liquid discharge device is of great significance for promoting the fully immersed liquid-cooled battery system. Summary of the Invention

[0004] Due to the problems existing in the prior art, the present invention proposes a fully immersed liquid-cooled battery pack and an internal gas-liquid discharge device thereof, which can adapt to variable pressure adjustment and can quickly relieve the internal pressure after thermal runaway while ensuring the sealing performance of the battery pack.

[0005] To achieve the above object, in a first aspect, the present invention provides an internal gas-liquid discharge device for a fully immersed liquid-cooled battery pack, including:

[0006] The outer shell is provided with an internal circulating liquid communication chamber at one end and an external circulating liquid communication chamber at the other end; several discharge holes are formed on the wall surface of the internal circulating liquid communication chamber;

[0007] The pressure regulating valve rod is axially arranged inside the outer shell, separating the internal circulating liquid communication chamber and the external circulating liquid communication chamber; the inner end of the pressure regulating valve rod is communicated with the internal circulating liquid of the battery pack through the internal circulating liquid communication chamber, and its outer end is communicated with the external circulating liquid of the battery pack through the external circulating liquid communication chamber;

[0008] The pressing mechanism is axially arranged between the outer end of the pressure regulating valve rod and the base of the external circulating liquid communication chamber;

[0009] When the fully immersed 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 pressing mechanism and the external circulating liquid pressure, the pressure regulating valve rod blocks the communication between the discharge hole and the internal circulating liquid of the battery pack;

[0010] When the fully immersed liquid-cooled battery pack has a thermal runaway or is approaching a thermal runaway, the internal pressure of the battery pack increases abnormally, the pressure at the inner end is greater than the pressure at the outer end, and the pressure regulating valve rod moves towards the external circulating liquid communication chamber, so that the gas-liquid inside the battery pack is discharged through the discharge hole.

[0011] Since the flow rate and pressure of the coolant inside and outside the battery will change with the battery working conditions, an explosion-proof valve with a single opening pressure is likely to cause coolant leakage or untimely opening, increasing the probability of thermal propagation. The gas-liquid discharge device of the present invention is closed or opened through the pressure difference between the inner end and the outer end, and 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, avoiding the coolant leakage or untimely opening caused by the single opening pressure of the explosion-proof valve and increasing the probability of thermal propagation.

[0012] Further, the discharge holes are arranged along the circumferential, radial or fixed direction of the internal circulating liquid communication chamber to meet the needs of different application environments.

[0013] Further, a limiting step for the pressure regulating valve rod is provided on the inner wall of the internal circulating liquid communication chamber and / or the external circulating liquid communication chamber to ensure that the rod-shaped regulating valve is in a suitable position and ensure that the external circulating pressure seals the inner end.

[0014] Further, the outer end face of the internal circulating liquid communication chamber is provided with a first connecting flange.

[0015] Further, the base is integrally formed with the external circulating liquid communication chamber.

[0016] Further, the inner end face of the base is detachably and fixedly connected to the external circulating liquid communication chamber through a second connecting flange.

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

[0018] In a second aspect, the present invention provides a fully immersed liquid-cooled battery pack, including a battery pack and an internal cooling circulating liquid in which the battery pack is completely immersed. It is characterized in that it further includes the internal gas-liquid discharge device as described above; the internal circulating liquid communication chamber of the internal gas-liquid discharge device is connected to the internal cooling circulating liquid pipeline, and the external circulating liquid communication chamber is connected to the circulating liquid inlet.

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

[0020] (1) The gas-liquid discharge device of the present invention 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, avoiding coolant leakage caused by misopening due to the single opening pressure of the explosion-proof valve or increasing the probability of thermal runaway due to untimely opening.

[0021] (2) The gas-liquid discharge device of the present invention can be reused. Even if the internal circulating cooling system of the battery pack fails after thermal runaway, under the action of the pressing mechanism, it can still ensure that the gas-liquid discharge device is normally closed.

[0022] (3) The gas-liquid discharge device of the present invention has a simple structure, is easy to process, has no special-shaped structural parts, and has a low cost. It can be widely applied to immersed cooling battery systems of various systems and space structures. Description of the Drawings

[0023] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, the present invention and its features, shape, and advantages will become more obvious. The same reference numerals indicate the same parts in all the drawings. The drawings are not drawn to scale, and the emphasis is on showing the gist of the present invention.

[0024] Figure 1 It is a three-dimensional structural schematic diagram of the gas-liquid discharge device in an embodiment of the present invention.

[0025] Figure 2 It is an exploded view of the gas-liquid discharge device in an embodiment of the present invention.

[0026] Figure 3 It is an axial sectional view of the gas-liquid discharge device in a normal working state of the battery pack in an embodiment of the present invention.

[0027] Figure 4 It is an axial sectional view of the gas-liquid discharge device in a thermal runaway state of the battery pack in an embodiment of the present invention.

[0028] Figure 5 It is a connection structure schematic diagram of the fully immersed liquid-cooled battery pack and the gas-liquid discharge device in another embodiment of the present invention.

[0029] Figure 6 For Figure 5 An enlarged view of part A in

[0030] In the accompanying drawings: 1. Outer shell; 11. Internal circulating liquid communication chamber; 12. External circulating liquid communication chamber; 13. Drain hole; 121. Base; 111. First connecting flange; 122. Second connecting flange;

[0031] 2. Pressure regulating valve rod; 21. Inner end; 22. Outer end; 23. Limiting step;

[0032] 3. Compression mechanism;

[0033] 4. Battery pack; 5. Connecting pipe; 6. Circulating liquid inlet; 7. Outlet. Specific embodiments

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

[0035] In the description of the present application, unless otherwise clearly defined and limited, the terms "arranged", "provided with", and "connected" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; the method may be welding or threaded connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

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

[0037] Embodiment 1

[0038] Refer to Figures 1 to 3 , this embodiment provides an internal gas-liquid discharge device for a fully immersed liquid-cooled battery pack, including: an outer shell 1, a pressure regulating valve rod 2, and a compression mechanism 3.

[0039] One end of the outer shell 1 is provided with an internal circulating liquid communication chamber 11, and the other end is provided with an external circulating liquid communication chamber 12; a plurality of drain holes 13 are opened on the wall surface of the internal circulating liquid communication chamber 11. The drain holes 13 can be arranged along the circumferential, radial or fixed direction of the internal circulating liquid communication chamber 11 to meet the needs of different application environments.

[0040] The pressure regulating valve stem 2 is axially arranged inside the housing 1, separating the internal circulating liquid communication chamber 11 and the external circulating liquid communication chamber 12; the inner end 21 of the pressure regulating valve stem 2 is communicated with the internal circulating liquid of the battery pack through the internal circulating liquid communication chamber 11, and its outer end 22 is communicated with the external circulating liquid of the battery pack through the external circulating liquid communication chamber 12. The pressure at the inner end 21 is equal to the internal pressure of the battery pack. When the battery is working normally, the internal pressure of the battery pack is equal to the pressure of the internal circulating liquid of the battery pack at the connection point. Due to the frictional pressure loss and local pressure loss of the internal coolant during the circulating flow, the pressure at the circulating liquid inlet will be greater than the internal pressure of the battery pack. Under normal working conditions, the pressure at the outer end 22 is always greater than the pressure at the inner end 21. Through the pressure difference between the inner end 21 and the outer end 22, the axial movement of the valve stem is realized.

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

[0042] See Figure 3 , when the fully immersed liquid-cooled battery pack is working normally, 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 circulating liquid pressure, the pressure regulating valve stem 2 blocks the connection between the discharge hole 13 and the internal circulating liquid of the battery pack, preventing the internal circulating liquid of the battery pack from leaking. Since the flow rate and pressure of the coolant will change with the working conditions, the internal pressure of the battery pack will also change. Thus, the pressures at both ends of the internal circulating liquid communication chamber and the external circulating liquid communication chamber will change. Therefore, the pressure difference between the two ends of the pressure regulating valve stem 2 will change according to the operating conditions of the battery pack, adapting to the dynamic changes of the external circulating liquid pressure and the internal pressure of the battery pack within a wide range, while an explosion-proof valve with a single opening pressure cannot handle this environment well.

[0043] See Figure 4, when thermal runaway occurs or is about to occur in a fully immersed liquid-cooled battery pack (for example, thermal runaway occurs in a certain battery in the battery pack), the pressure inside the battery pack increases abnormally (for example, a series of heat-generating and gas-generating chain reactions occur inside the battery, and the pressure inside the battery pack rises sharply). The pressure at the inner end 21 is greater than the pressure at the outer end 22. The pressure regulating valve rod 2 moves towards the external circulating liquid communication chamber 12, causing the pressing mechanism 3 to be in a compressed state. The gas-liquid inside the battery pack is discharged through the discharge hole 13. It can be seen that the size of the pressure inside the battery pack determines the opening size of the discharge hole. After the thermal runaway of the battery inside the battery pack is completed, under the action of the pressing mechanism 3, the gas-liquid discharge device can still return to the closed state to prevent the internal cooling efficiency from decreasing due to the complete leakage of the coolant inside the battery pack.

[0044] As a preferred embodiment, refer to Figure 3 , a limiting step 23 for the pressure regulating valve rod 2 is provided on the inner wall of the internal circulating liquid communication chamber 11 and / or the external circulating liquid communication chamber 12 to ensure that the rod-shaped regulating valve is in a suitable position and ensure that the external circulating pressure seals the inner end.

[0045] As a preferred embodiment, the internal circulating liquid communication chamber 11 and the external circulating liquid communication chamber 12 are cylindrical, and the inner diameter of the internal circulating liquid communication chamber 11 is smaller than the inner diameter of the external circulating liquid communication chamber 12.

[0046] As a preferred embodiment, refer to Figure 2 , the inner end face of the base 121 is detachably and fixedly connected to the external circulating liquid communication chamber 12 through the second connecting flange 122.

[0047] From the above description, it can be seen that the internal gas-liquid discharge device of this embodiment utilizes the differential pressure evolution law of the fully immersed 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 changes in the external coolant circulation pipeline of the battery pack and the internal pressure of the battery pack, and avoids the coolant leakage caused by the single opening pressure of the explosion-proof valve or the increased probability of thermal spread due to untimely opening. This internal gas-liquid discharge device has a wide range of applications and can be widely applied to immersed cooling battery systems of various systems and spatial structures.

[0048] Embodiment 2

[0049] Refer to Figure 5 , this embodiment provides a fully immersed liquid-cooled battery pack 4, including a battery pack, an internal cooling circulating liquid in which the battery pack is completely immersed, and an internal gas-liquid discharge device as described in Embodiment 1. The internal circulating liquid communication chamber 11 of the internal gas-liquid discharge device is connected to the internal cooling circulating liquid pipeline, and the external circulating liquid communication chamber 12 is connected to the circulating liquid inlet 6 through a connecting pipeline 5.

[0050] As a preferred embodiment, refer to Figure 1and Figure 6 On the outer end face of the internal circulating liquid connection chamber 11, a first connection flange 111 is provided. The internal circulating liquid connection chamber 11 is connected to the internal cooling circulating liquid pipeline of the battery pack through the first connection flange 111.

[0051] During normal operation, due to the frictional pressure loss and local pressure loss along the way, the pressure at the circulating liquid inlet 6 is higher than that at the outlet 7. That is to say, inside the fully immersed battery pack, the pressure at the circulating liquid inlet 6 should be the highest. Connecting the external circulating liquid connection chamber 12 to the circulating liquid inlet 6 can ensure that the pressure of the external cooling circulating liquid of the battery pack plus the pressing mechanism can press the inner end 21 tightly without leakage.

[0052] In summary, the present invention provides a fully immersed liquid-cooled battery pack and its internal gas-liquid discharge device, including: a housing, a pressure regulating valve rod, and a pressing mechanism. One end of the housing is provided with an internal circulating liquid connection chamber, and the other end is provided with an external circulating liquid connection chamber; a plurality of discharge holes are opened on the wall surface of the internal circulating liquid connection chamber; the pressure regulating valve rod is axially arranged inside the housing to separate the internal circulating liquid connection chamber and the external circulating liquid connection chamber; the inner end of the pressure regulating valve rod is connected to the internal circulating liquid of the battery pack through the internal circulating liquid connection chamber, and its outer end is connected to the external circulating liquid of the battery pack through the external circulating liquid connection chamber; the pressing mechanism is axially arranged between the outer end of the pressure regulating valve rod and the base of the external circulating liquid connection chamber. The present invention can adapt to the opening and closing of the variable pressure regulating valve rod inside the battery, and can quickly release the internal pressure after thermal runaway while ensuring the sealing performance of the battery pack.

[0053] Those skilled in the art should understand that those skilled in the art can realize variations in combination with the prior art and the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention and will not be elaborated here.

[0054] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and the systems and structures not described in detail should be understood to be implemented in a common manner in the art; any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present invention, which does not affect the essence of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the protection of the technical solution of the present invention.

Claims

1. An internal gas-liquid discharge device for a fully immersed liquid-cooled battery pack, characterized in that Comprising: A housing (1), with an internal circulating liquid communication chamber (11) provided at one end and an external circulating liquid communication chamber (12) provided at the other end; a plurality of drain holes (13) are formed on the wall surface of the internal circulating liquid communication chamber (11); A pressure regulating valve rod (2), axially arranged inside the housing (1), separating the internal circulating liquid communication chamber (11) and the external circulating liquid communication chamber (12); the inner end (21) of the pressure regulating valve rod (2) is communicated with the internal circulating liquid of the battery pack through the internal circulating liquid communication chamber (11), and its outer end (22) is communicated with the external circulating liquid of the battery pack through the external circulating liquid communication chamber (12); A pressing mechanism (3), axially arranged between the outer end (22) of the pressure regulating valve rod (2) and the base (121) of the external circulating liquid communication chamber (12); When the fully immersed liquid-cooled battery pack is operating normally, the internal pressure of the battery pack is in a normal state. Under the action of the pre-tightening force of the pressing mechanism (3) and the external circulating liquid pressure, the pressure regulating valve rod (2) blocks the communication between the drain hole (13) and the internal circulating liquid of the battery pack; When the fully immersed liquid-cooled battery pack has a thermal runaway or is approaching a thermal runaway, the internal pressure of the battery pack increases abnormally. The pressure at the inner end (21) is greater than the pressure at the outer end (22). The pressure regulating valve rod (2) moves towards the external circulating liquid communication chamber (12), enabling the internal gas-liquid of the battery pack to be discharged through the drain hole (13).

2. The internal gas-liquid discharge device of the fully immersed liquid-cooled battery pack according to claim 1, characterized in that The drain holes (13) are arranged along the circumferential, radial or fixed direction of the internal circulating liquid communication chamber (11).

3. The internal gas-liquid discharge device of the fully immersed liquid-cooled battery pack according to claim 1, characterized in that, A limiting step (23) of the pressure regulating valve rod (2) is provided on the inner wall of the internal circulating liquid communication chamber (11) and / or the external circulating liquid communication chamber (12).

4. The internal gas-liquid discharge device of the fully immersed liquid-cooled battery pack according to claim 1, wherein, A first connecting flange (111) is provided on the outer end face of the internal circulating liquid communication chamber (11).

5. The internal gas-liquid discharge device of the fully immersed liquid-cooled battery pack according to claim 1, wherein The inner end face of the base (121) is detachably and fixedly connected to the external circulating liquid communication chamber (12) through a second connecting flange (122).

6. The internal gas-liquid discharge device of the fully immersed liquid-cooled battery pack according to claim 1, wherein, The pressing mechanism (3) is a spring.

7. A fully immersed liquid-cooled battery pack, including a battery pack with a fully immersed structure inside the battery pack, characterized in that, It further includes an internal gas-liquid discharge device as described in any one of claims 1 to 6; the internal circulating liquid communication chamber (11) of the internal gas-liquid discharge 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. The external circulating liquid communication chamber (12) is connected to the circulating liquid inlet (6).

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