Battery pack, energy storage device and control method

Abstract

The invention relates to a battery pack, an energy storage device and a control method, which can reduce the liquid level height of immersion liquid in a battery pack accommodating cavity so as to reduce the contact area between the immersion liquid and a heat pipe, even enable the immersion liquid not to be in contact with the heat pipe so as to reduce the heat exchange efficiency between the immersion liquid and the heat pipe, and correspondingly, improve the heat exchange efficiency between the immersion liquid and the heat pipe. And the efficiency of heat exchange between the immersion liquid and the gas outside the accommodating cavity through the heat pipe is relatively low, so that the working energy consumption of the battery heat management equipment is relatively low, and the advantage of energy conservation is achieved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery pack, an energy storage device and a control method. Background Art

[0002] The energy storage device includes a battery pack and a battery thermal management device, and the battery thermal management device is used to exchange heat with the battery pack to keep the temperature inside the battery pack within a suitable temperature range. In the prior art, the working energy consumption of the battery thermal management device is relatively large. Summary of the invention

[0003] In view of this, the present application provides a battery pack, an energy storage device and a control method, aiming to improve the problem of high energy consumption of battery thermal management equipment.

[0004] In a first aspect, the present application provides a battery pack, which includes a shell, a battery cell, a heat pipe and a liquid level sensor; the shell is provided with a accommodating cavity, the accommodating cavity is used to accommodate immersion liquid, and at least one battery cell is arranged in the accommodating cavity; the heat pipe extends from the accommodating cavity to the outside of the accommodating cavity; the liquid level sensor is used to detect the liquid level at a first position in the accommodating cavity, and the height of at least part of the structure of the part of the heat pipe located in the accommodating cavity is greater than the height at the first position.

[0005] When the battery cell has a need to dissipate heat, and when the temperature of the gas outside the receiving chamber is greater than the temperature of the immersion liquid in the receiving chamber, a liquid level sensor can be used to detect whether the liquid level of the immersion liquid is greater than the height of the first position. If the liquid level sensor detects that the liquid level of the immersion liquid is greater than the height of the first position, the liquid level sensor is used to generate a feedback signal, and the liquid level of the immersion liquid can be adjusted according to the feedback signal to reduce the contact area between the immersion liquid and the heat pipe, or even to prevent the immersion liquid from contacting the heat pipe, so as to reduce the heat exchange efficiency between the immersion liquid and the heat pipe. Accordingly, the efficiency of heat exchange between the immersion liquid and the gas outside the receiving chamber through the heat pipe is relatively low, so that the heat dissipation energy consumption of the battery thermal management device is relatively low.

[0006] Similarly, when there is a need to heat the battery cell and when the temperature of the gas outside the containment chamber is lower than the temperature of the immersion liquid in the containment chamber, the liquid level of the immersion liquid can also be lowered according to the feedback signal of the liquid level sensor to reduce the efficiency of heat exchange between the immersion liquid and the gas outside the containment chamber through the heat pipe, so that the heating energy consumption of the battery thermal management device is relatively low.

[0007] Of course, when the battery pack is in a stopped state, the liquid level of the immersion liquid can also be lowered according to the feedback signal of the liquid level sensor to reduce the efficiency of heat exchange between the immersion liquid and the gas outside the accommodating cavity through the heat pipe, so that the working energy consumption (heating energy consumption or heat dissipation energy consumption) of the battery thermal management device is relatively low.

[0008] Optionally, the height of the first position is less than or equal to the height of the bottom of the portion of the heat pipe located in the accommodating cavity.

[0009] Optionally, the liquid level sensor includes a first liquid level sensing portion, which is used to detect the liquid level at a first position; the first liquid level sensing portion is arranged at the bottom of a portion of the heat pipe located in the accommodating cavity.

[0010] Optionally, the liquid level sensor is also used to detect the liquid level at a second position in the accommodating chamber, and the height of the second position is greater than the height of the first position.

[0011] Optionally, the heat pipe is disposed through the top wall of the shell, and the height of the second position is the same as the height of the highest position of the accommodating cavity.

[0012] Optionally, the liquid level sensor includes a second liquid level sensing portion, which is used to detect the liquid level at the second position; the second liquid level sensing portion is arranged on the inner surface of the top wall of the shell.

[0013] Optionally, the battery pack further includes a vent valve, which is disposed through the shell and is used for gas to flow between the inside and outside of the accommodating cavity.

[0014] In a second aspect, the present application provides an energy storage device, the energy storage device includes the battery pack described above, and the energy storage device also includes a container and a drive pump, the container is used to contain immersion liquid; the drive pump is used to drive the immersion liquid to flow from the battery pack to the container to reduce the liquid level of the immersion liquid in the battery pack. The energy storage device also includes the technical effect of reducing the heat dissipation energy consumption of the battery thermal management device described above, which will not be repeated here.

[0015] In a third aspect, the present application provides a control method for an energy storage device, the control method for the energy storage device comprising: enabling the energy storage device to be in at least a first state, lowering the liquid level of the immersion liquid in the battery pack in the first state, and using a liquid level sensor to detect the liquid level of the immersion liquid, and when the liquid level of the immersion liquid is less than or equal to the height of the first position, stopping lowering the liquid level of the immersion liquid in the battery pack.

[0016] Optionally, in the first state, at least part of the immersion liquid in the battery pack is pumped out by using a driving pump, so that the vent valve of the battery pack is in a venting state, so that gas outside the battery pack can enter the battery pack.

[0017] The control method of the present application can meet the need of reducing the working energy consumption of the battery thermal management device by lowering the liquid level of the immersion liquid.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 and Figure 2 A schematic cross-sectional structural diagram of a battery pack provided in the present application in a specific embodiment, wherein the battery pack is filled with an immersion liquid; Figure 3 and Figure 4 It is a partial cross-sectional schematic diagram of the housing, the accommodating cavity and the heat pipe, wherein a first position is provided in the accommodating cavity; Figure 5 It is a partial cross-sectional schematic diagram of the housing, the accommodating cavity, the heat pipe and the first liquid level sensing part; Figure 6 and Figure 7 It is a partial cross-sectional schematic diagram of a housing, a receiving cavity and a heat pipe, wherein a first position and a second position are provided in the receiving cavity; Figure 8 It is a partial cross-sectional schematic diagram of a housing, a receiving cavity, a heat pipe, a first liquid level sensing portion, and a second liquid level sensing portion, wherein a first position and a second position are provided in the receiving cavity; Fig. 9 It is a partial cross-sectional schematic diagram of a housing, a receiving cavity, a heat pipe and a liquid level sensor, wherein a first position and a second position are provided in the receiving cavity; Fig.10 It is a partial cross-sectional schematic diagram of a housing, a receiving cavity and a vent valve, wherein the receiving cavity is filled with an immersion liquid; Fig.11 A partial cross-sectional schematic diagram of a housing, a receiving chamber and a vent valve in another specific embodiment, wherein the receiving chamber is filled with an immersion liquid; Fig.12 and Fig.13 A schematic cross-sectional structural diagram of a battery pack provided in the present application in another specific embodiment, wherein the battery pack is filled with an immersion liquid; Fig.14 and Fig.15 A schematic cross-sectional structural diagram of a battery pack provided in the present application in another specific embodiment, wherein the battery pack is filled with an immersion liquid; Fig.16 is a schematic structural diagram of a heat pipe in a specific embodiment; Fig.17 A schematic diagram of a cross-sectional structure of a battery pack provided in the present application in other specific embodiments; Fig.18 for Fig.17 A schematic diagram of the structure of the battery pack in a three-dimensional perspective; Fig.19 A schematic diagram of the pipe connections of a battery pack, a drive pump, a container and a battery thermal management device in a specific implementation; Fig. 20 The present invention is a schematic diagram of the pipeline connections among a battery pack, a drive pump, a container and a battery thermal management device in another specific implementation.

[0021] Reference numerals: 10-Battery pack; 1- housing; 11-accommodating chamber; 111- first accommodating chamber; 112 - second accommodating chamber; 11a - first position; 11b - second position; 12-Gas collecting slope; 13- partition; 14a-first liquid port; 14b-second liquid port; 2-Battery monomer; 3- Heat pipe; 31- first heat exchange part; 32- second heat exchange part; 4-Liquid level sensor; 4a-first liquid level sensing part; 4b-second liquid level sensing part; 5-heat exchanger; 6- Fan; 7-Ventilation valve; 8- Airbag; 20 - immersion liquid; 30-driving pump; 40-Container; 50-Battery thermal management equipment. DETAILED DESCRIPTION

[0022] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0023] It should be clear that the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present application. The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0024] In the drawings of this article, directions X, Y and Z are perpendicular to each other, and direction Y is parallel to the height direction.

[0025] In a first aspect, an embodiment of the present application provides a battery pack, which can be charged by an external power grid to store electrical energy, and the battery pack can also output electrical energy to the external power grid or electrical equipment.

[0026] The battery pack includes a housing and at least one battery cell, which is located inside the housing. A battery cell is a secondary battery, which can also be called a rechargeable battery or storage battery. A secondary battery is a battery that can be charged after being discharged to activate the active material inside the battery and continue to provide electrical energy.

[0027] If the battery pack includes at least two battery cells, the at least two battery cells can form a battery module located in the housing, wherein the electrical connection relationship between the at least two battery cells in the same battery module includes series connection, parallel connection or mixed connection, and mixed connection means that multiple battery cells are connected in series and in parallel. In other embodiments, a part of the battery cells can form a battery module, and another part of the battery cells can form another battery module, and at least two battery modules can be connected in series, in parallel or mixed connection.

[0028] Please refer to Figure 1 As shown, a receiving chamber 11 is provided in the housing 1, and at least two battery cells 2 are located in the receiving chamber 11. The receiving chamber 11 is also used to receive an immersion liquid 20. The immersion liquid may include at least one of hydrofluoroether, hydrocarbon and silicone oil.

[0029] Please refer to Figure 1As shown, the immersion liquid 20 is used to exchange heat with the battery cell 2. When the internal temperature of the battery cell 2 is greater than the upper limit of the reliable operating temperature range, the immersion liquid 20 can be used to absorb the heat of the battery cell 2 to reduce the internal temperature of the battery cell 2, thereby reducing the possibility of explosion or thermal deformation of the battery cell 2. When the internal temperature of the battery cell 2 is less than the lower limit of the reliable operating temperature range, the immersion liquid 20 is used to transfer heat to the battery cell 2 to increase the internal temperature of the battery cell 2, thereby improving the working efficiency (charging efficiency or discharging efficiency) of the battery cell 2.

[0030] It should be noted that the reliable operating temperature range refers to the temperature range that ensures that the battery cells are not prone to thermal deformation or explosion problems, which may affect the safety of use, while still maintaining a high working efficiency.

[0031] It should be noted that the immersion liquid must also have good insulation properties to reduce the possibility of electrical short circuit problems between multiple battery cells.

[0032] Please refer to Figure 1 As shown, the immersion liquid 20 in the accommodating chamber 11 can achieve heat exchange outside the accommodating chamber 11 via a pipeline (not shown in the figure) located outside the accommodating chamber 11 .

[0033] Please refer to Figure 1 As shown, when the battery cell 2 needs to be cooled, the immersion liquid 20 located in the accommodating cavity 11 can flow to the outside of the accommodating cavity 11 after absorbing the heat of the battery cell 2, and then the immersion liquid 20 located outside the accommodating cavity 11 can dissipate the heat outside the accommodating cavity 11. After dissipating the heat, the immersion liquid 20 located outside the accommodating cavity 11 can flow back into the accommodating cavity 11 to continue absorbing the heat of the battery cell 2, thereby realizing a heat dissipation cycle process.

[0034] Please refer to Figure 1 As shown, when the battery cell 2 needs to be heated, the immersion liquid 20 located in the accommodating cavity 11 can flow to the outside of the accommodating cavity 11 after transferring heat to the battery cell 2, and then the immersion liquid 20 located outside the accommodating cavity 11 can absorb heat outside the accommodating cavity 11. After absorbing heat, the immersion liquid 20 located outside the accommodating cavity 11 can flow back into the accommodating cavity 11 to continue transferring heat to the battery cell 2, thereby realizing a heating cycle process.

[0035] Among them, the immersion liquid 20 located outside the accommodating cavity 11 can realize secondary heat exchange with the battery thermal management device (not shown in the figure) located outside the accommodating cavity 11. The battery thermal management device mainly includes a compressor, an evaporator, a condenser and an expansion valve.

[0036] Generally, multiple battery packs are installed together in a battery compartment (not shown in the figure) of an energy storage device. The energy storage device also includes a gas thermal management device (also known as an air conditioner or a box-type air conditioner). The gas thermal management device is used to adjust the temperature of the gas in the battery compartment to reduce the influence of the gas in the battery compartment on the internal temperature of the battery pack, thereby reducing the working energy consumption of the battery thermal management device.

[0037] It should be noted that the battery compartment can be a compartment dedicated to placing battery packs, and accordingly, the gas thermal management device is also mainly responsible for regulating the temperature of the gas in the battery compartment.

[0038] It should be noted that the gas thermal management device and the battery thermal management device described above are not the same device. The gas thermal management device and the battery thermal management device may be separate devices or integrated devices.

[0039] When the battery thermal management device and the immersion liquid 20 are used to dissipate heat to the battery cell 2, and when the gas thermal management device is also used to dissipate heat to the gas in the battery compartment (the gas outside the battery pack shell), it can also be said that when the temperature of the immersion liquid in the battery pack is higher than the temperature of the gas in the battery compartment, the heat of the immersion liquid 20 in the battery pack can be transferred to the gas in the battery compartment to improve the heat dissipation efficiency of the battery cell 2.

[0040] When the battery thermal management device and the immersion liquid 20 are used to heat the battery cell 2, and when the gas thermal management device is also used to heat the gas in the battery compartment (the gas outside the battery pack shell), it can also be said that when the temperature of the immersion liquid in the battery pack is lower than the temperature of the gas in the battery compartment, the immersion liquid 20 in the battery pack can absorb the heat of the gas in the battery compartment to improve the heating efficiency of the battery cell 2.

[0041] In order to achieve the above-mentioned heat exchange between the immersion liquid in the battery pack and the battery compartment gas and improve the heating efficiency or heat dissipation efficiency of the battery cell, the battery pack of the embodiment of the present application may also include a heat pipe, and the immersion liquid 20 located in the accommodating cavity 11 can achieve heat exchange with the gas in the battery compartment with the help of the heat pipe.

[0042] The working principle of the heat pipe is as follows: when the temperature of the evaporation part of the heat pipe rises, the liquid medium in the evaporation part absorbs heat and evaporates into a gaseous medium. The gaseous medium flows to the condensation part of the heat pipe under the power of heat diffusion. The gaseous medium releases heat in the condensation part and condenses to form a liquid medium. The liquid medium flows back to the evaporation part by capillary action or gravity. It should be noted that the part with a higher temperature in the heat pipe is the evaporation part, and the part with a lower temperature in the heat pipe is the condensation part. The position of the evaporation part and the position of the condensation part are not fixed and depend on the actual working conditions of the heat pipe.

[0043] It should be noted that in some application scenarios, it is not necessary to use heat pipes and immersion fluid to absorb the heat of the gas in the battery compartment to assist in heating the battery cells, but at least heat pipes and immersion fluid can be used to assist in transferring the heat of the battery cells to the gas in the battery compartment, that is, there are many demands for improving the heat dissipation efficiency of the battery cells.

[0044] Please refer to Figure 1 As shown, the heat pipe 3 extends from the inside of the accommodating cavity 11 to the outside of the accommodating cavity 11. When it is necessary to dissipate heat to the battery cell 2, the immersion liquid 20 absorbs the heat of the battery cell 2, and the portion of the heat pipe 3 that contacts the immersion liquid 20 can be an evaporation portion, and the portion of the heat pipe 3 that is located outside the accommodating cavity 11 can be a condensation portion, which can transfer heat to the gas outside the accommodating cavity 11 (the gas outside the battery pack shell or the gas inside the battery compartment), and the gas outside the accommodating cavity 11 is then dissipated by the gas thermal management device. When it is necessary to heat the battery cell 2, the portion of the heat pipe 3 that is located outside the accommodating cavity 11 can be an evaporation portion, that is, the evaporation portion can absorb the heat of the gas outside the accommodating cavity 11 (the heat provided by the gas thermal management device), and the portion of the heat pipe 3 that contacts the immersion liquid 20 can be a condensation portion, and the condensation portion can transfer heat to the battery cell 2 through the immersion liquid 20.

[0045] However, the heat exchange between the immersion liquid and the gas outside the containing cavity through the heat pipe is not suitable for all working conditions, such as the following conditions 1, 2 and 3.

[0046] Condition 1: When the battery thermal management device and immersion liquid are used to dissipate heat from the battery cell, and when the temperature of the gas outside the containment cavity is higher than the temperature of the immersion liquid inside the containment cavity, the heat of the gas outside the containment cavity may be transferred to the immersion liquid through the heat pipe, and the immersion liquid may absorb not only the heat of the battery cell but also the heat of the gas outside the containment cavity, and the heat absorbed by the immersion liquid will be transferred to the battery thermal management device. Therefore, the heat dissipation energy consumption of the battery thermal management device is relatively large.

[0047] Condition 2: When the battery thermal management device and the immersion liquid are used to heat the battery cell, and when the temperature of the gas outside the receiving chamber is lower than the temperature of the immersion liquid inside the receiving chamber, the immersion liquid not only transfers heat to the battery cell but also transfers heat to the gas outside the receiving chamber through the heat pipe. Therefore, the heating energy consumption of the battery thermal management device is also relatively large.

[0048] Condition 3: Since the energy storage device may include multiple battery packs, a portion of the battery packs may be in a working state (the battery cells are used for charging or discharging), and another portion of the battery packs may be in a stopped state (the battery cells are neither used for charging nor discharging). The battery pack in a working state may have a demand for higher heat dissipation efficiency or a demand for higher heating efficiency. Therefore, the battery pack in a working state not only needs to use the immersion liquid and the thermal management system to implement heat exchange, but also needs to use the immersion liquid, heat pipes, gas outside the containment cavity, and gas thermal management equipment to implement auxiliary heat exchange. For the battery pack in a stopped state, the battery pack in a stopped state has no heat dissipation demand or heating demand, but the immersion liquid in the battery pack in a stopped state may undergo relatively ineffective heat exchange through the heat pipe, the gas outside the containment cavity, and the gas thermal management equipment. Therefore, there is a relatively large defect in the working energy consumption (heat dissipation energy consumption or heating energy consumption) of the battery thermal management equipment, and accordingly, there is also a relatively large defect in the working energy consumption of the gas thermal management equipment.

[0049] In order to reduce the working energy consumption of the battery thermal management device, the battery pack of the embodiment of the present application can meet the following settings: In the above-mentioned condition 1, condition 2 or condition 3, the liquid level height (also known as liquid surface height) of the immersion liquid 20 in the accommodating chamber 11 can be lowered to reduce the contact area between the immersion liquid 20 and the heat pipe 3, or even to make the immersion liquid 20 and the heat pipe 3 not in contact with each other, so as to reduce the heat exchange efficiency between the immersion liquid 20 and the heat pipe 3. Accordingly, the efficiency of heat exchange between the immersion liquid 20 and the external gas of the accommodating chamber 11 through the heat pipe 3 is relatively low, so that the working energy consumption of the battery thermal management device is relatively low, that is, it has an energy-saving advantage. Among them, in the third condition, if the liquid level of the immersion liquid 20 in the accommodating chamber 11 is reduced, not only the working energy consumption of the battery thermal management device can be reduced, but also the working energy consumption of the gas thermal management device can be reduced.

[0050] When it is necessary to utilize the immersion liquid in the accommodating chamber to exchange heat with the gas outside the accommodating chamber through the heat pipe, the liquid level of the immersion liquid 20 in the accommodating chamber 11 can be increased to increase the contact area between the immersion liquid 20 and the heat pipe 3, so as to improve the heat exchange efficiency between the immersion liquid 20 and the heat pipe 3. Accordingly, the efficiency of heat exchange between the immersion liquid 20 and the gas outside the accommodating chamber 11 through the heat pipe 3 is relatively high.

[0051] by Figure 1 and Figure 2 For example, you can use Figure 1 The level of the immersion liquid 20 is shown to increase to Figure 2 The liquid level of the immersion liquid 20 shown can also be adjusted as follows: Figure 2 The level of the immersion liquid 20 is shown to be reduced to Figure 1The level of the immersion liquid 20 is shown.

[0052] According to the above content, it can be known that the difference in the liquid level of the immersion liquid 20 can affect the heat exchange efficiency between the immersion liquid 20 and the heat pipe 3. In the process of adjusting the liquid level of the immersion liquid 20, it is necessary to use a sensor to detect the change in the liquid level of the immersion liquid 20, and adjust the liquid level of the immersion liquid 20 in a closed loop according to the feedback signal of the sensor. Therefore, the battery pack of the embodiment of the present application may also include a liquid level sensor, which is used to detect the liquid level of the immersion liquid 20. Figure 3 or Figure 4 The liquid level at the first position 11a in the accommodating chamber 11 is shown, and the height of at least a part of the structure of the portion of the heat pipe 3 located in the accommodating chamber 11 is greater than the height of the first position 11a. Figure 3 and Figure 4 The height of the first position 11a is indicated by a dot-dash line.

[0053] It should be noted that the portion of the heat pipe 3 located in the accommodating cavity 11 may be an evaporation portion or a condensation portion, depending on the working condition of the heat pipe 3 .

[0054] In case of situation 1, situation 2 or situation 3 above, please refer to Figure 3 or Figure 4 As shown, if the liquid level of the immersion liquid (not shown in the figure) is greater than the height of the first position 11a, the liquid level sensor can detect that there is immersion liquid at the first position 11a, that is, the liquid level sensor can output a feedback signal about "the liquid level of the immersion liquid is greater than the height of the first position 11a", and the feedback signal can be obtained by the control device. The control device that obtains the feedback signal can reduce the liquid level of the immersion liquid so that the liquid level of the immersion liquid is less than the height of the first position 11a, so as to reduce the heat exchange efficiency between the immersion liquid and the heat pipe 3, thereby reducing the working energy consumption of the battery thermal management device.

[0055] When the liquid level of the immersion liquid is lowered to a height lower than the height of the first position 11a, the liquid level sensor does not detect the presence of immersion liquid at the first position 11a, that is, the liquid level sensor can output a feedback signal that "the liquid level of the immersion liquid is lower than the height of the first position 11a", and the feedback signal can be obtained by the control device, and the control device that obtains the feedback signal can stop lowering the liquid level of the immersion liquid.

[0056] Please refer to Figure 3-Figure 4As shown, when the liquid level of the immersion liquid is less than the height of the first position 11a, there is more gas above the immersion liquid or above the first position 11a in the shell 1. The thermal conductivity of the gas is lower than that of the immersion liquid, the thermal conductivity of the gas is lower than that of the heat pipe 3, and the thermal conductivity of the gas is lower than that of the shell 1. When there is more gas in the shell 1, the heat exchange efficiency between the immersion liquid in the shell 1 and the gas outside the shell 1 can be reduced.

[0057] When it is necessary to use the immersion liquid in the containment cavity to exchange heat with the gas outside the containment cavity through the heat pipe, please refer to Figure 3 or Figure 4 As shown, if the liquid level of the immersion liquid is less than the height of the first position 11a, the liquid level sensor can detect that there is no immersion liquid at the first position 11a, that is, the liquid level sensor can output a feedback signal about "the liquid level of the immersion liquid is less than the height of the first position 11a", and the feedback signal can be obtained by the control device. The control device that obtains the feedback signal can increase the liquid level of the immersion liquid so that the liquid level of the immersion liquid is greater than the height of the first position 11a, so as to increase the heat exchange efficiency between the immersion liquid and the heat pipe 3, thereby increasing the heat exchange efficiency between the immersion liquid in the accommodating chamber 11 and the gas outside the accommodating chamber 11.

[0058] It should be noted that the control device may be a device inside the battery pack. In other embodiments, the control device may also be a device independent of the battery pack and located outside the battery pack. The subsequent content of this article will introduce the structure included in the control device in detail.

[0059] Optionally, see Figure 4 As shown, the height of the first position 11a may be equal to the height of the bottom of the portion of the heat pipe 3 located in the accommodating cavity 11. Under this setting, in the above-mentioned condition 1, condition 2 or condition 3, the control device may make the liquid level of the immersion liquid lower than the height of the bottom of the portion of the heat pipe 3 located in the accommodating cavity 11 according to the feedback signal of the liquid level sensor, so that the immersion liquid is not in direct physical contact with the heat pipe 3, and the heat exchange efficiency between the immersion liquid and the heat pipe 3 is lower, thereby further reducing the working energy consumption of the battery thermal management device.

[0060] In other embodiments (not shown in the figures), the height of the first position may also be smaller than the height of the bottom of the portion of the heat pipe located in the accommodating cavity.

[0061] Optionally, see Figure 5 As shown, the liquid level sensor includes a first liquid level sensing portion 4a, which is used to detect the liquid level at the first position 11a, and the first liquid level sensing portion 4a is arranged at the bottom of the portion of the heat pipe 3 located in the accommodating cavity 11. Figure 5If the first liquid level sensor 4a is disposed at the bottom of the portion of the heat pipe 3 located in the accommodating cavity 11, the first liquid level sensor 4a can accurately detect whether the bottom of the portion of the heat pipe 3 located in the accommodating cavity 11 is in contact with the immersion liquid.

[0062] In other embodiments (not shown in the figures), the first liquid level sensor may also be disposed on the inner wall of the shell, as long as the height of the first liquid level sensor is less than or equal to the height of the bottom of the portion of the heat pipe located in the accommodating cavity.

[0063] Optionally, see Figure 6 As shown, the liquid level sensor is also used to detect the liquid level at the second position 11b in the accommodating chamber 11, and the height of the second position 11b is greater than the height of the first position 11a. Figure 6 and Figure 7 The height of the first position 11a and the height of the second position 11b are both indicated by dotted lines. Figure 6 As shown, when it is necessary to utilize the immersion liquid in the receiving chamber 11 to exchange heat with the gas outside the receiving chamber 11 through the heat pipe 3, and the liquid level of the immersion liquid is less than the height of the first position 11a, the control device can increase the liquid level of the immersion liquid according to the feedback signal of the liquid level sensor. When the liquid level of the immersion liquid is greater than or equal to the liquid level of the second position 11b, the liquid level sensor can detect that there is immersion liquid in the second position 11b, and the liquid level sensor can output a feedback signal about "the liquid level of the immersion liquid is greater than or equal to the liquid level of the second position 11b", which can be obtained by the control device, and the control device that obtains the feedback signal can stop increasing the liquid level of the immersion liquid. If the liquid level of the immersion liquid is greater than or equal to the height of the second position 11b, the contact area between the immersion liquid and the heat pipe 3 is relatively large, and the heat exchange efficiency between the immersion liquid and the heat pipe 3 is relatively high, so the heat exchange efficiency between the immersion liquid in the receiving chamber 11 and the gas outside the receiving chamber 11 through the heat pipe is high.

[0064] Among them, at least part of the structure of the portion of the heat pipe 3 located in the accommodating cavity 11 can be extended along the height direction of the battery pack (for example, a direction parallel to the direction Y). When the liquid level of the immersion liquid changes, the contact area between the heat pipe 3 and the immersion liquid is also different, and accordingly, the heat exchange efficiency between the heat pipe 3 and the immersion liquid is also different.

[0065] Optionally, see Figure 7As shown, the heat pipe 3 is passed through the top wall of the shell 1, and the height of the second position 11b is the same as the height of the highest position in the accommodating chamber 11. The highest position in the accommodating chamber 11 may also be the highest position of the inner wall surface of the shell 1. When the liquid level sensor detects that there is immersion liquid at the second position 11b, the control device may stop increasing the liquid level of the immersion liquid. At this time, the accommodating chamber 11 contains sufficient immersion liquid so that the contact area between the immersion liquid and the heat pipe 3 is large enough, so that the heat exchange efficiency between the immersion liquid and the heat pipe 3 is large enough, and thus the heat exchange efficiency between the immersion liquid in the accommodating chamber 11 and the gas outside the accommodating chamber 11 through the heat pipe is large enough.

[0066] Please refer to Figure 6 As shown, the heat pipe 3 can also be passed through the top wall of the shell 1, and the height of the second position 11b can be smaller than the highest position of the accommodating cavity 11, or in other words, the height of the second position 11b can be smaller than the height of the highest position of the inner wall of the shell 1, but the height of the second position 11b is still greater than the height of the first position 11a.

[0067] In other embodiments (not shown in the figures), the heat pipe may also be arranged through the side wall of the shell, and at least part of the structure of the portion of the heat pipe located in the accommodating cavity may be extended along the height direction of the battery pack, and the height of the second position may be equal to or less than the height of the highest position of the accommodating cavity, or in other words, the height of the second position may be equal to or less than the height of the highest position of the inner wall surface of the shell, but the height of the second position still needs to be greater than the height of the first position.

[0068] In other embodiments (not shown in the figures), the extension direction of at least a portion of the structure of the heat pipe penetrating the top wall of the shell and located in the accommodating cavity may intersect with the height direction but not be perpendicular to the height direction.

[0069] In other embodiments (not shown in the figure), the heat pipe may also be arranged through the side wall of the housing, but the extension direction of the portion of the heat pipe located in the accommodating cavity is perpendicular to the height direction of the battery pack. Accordingly, the liquid level sensor may be used to detect at least the first position.

[0070] It should be noted that if the heat pipe has a structure extending in the height direction, or if the heat pipe has a structure crossing the height direction but not perpendicular to the height direction, the influence of gravity on the liquid medium in the heat pipe makes it easier for heat to be transferred from the lower part of the heat pipe to the higher part of the heat pipe. Figure 1-Figure 7 In the embodiment, the rate at which heat from the portion of the heat pipe 3 located inside the accommodating cavity is transferred to the portion of the heat pipe 3 located outside the accommodating cavity is relatively large, while the rate at which heat from the portion of the heat pipe 3 located outside the accommodating cavity is transferred to the portion of the heat pipe 3 located inside the accommodating cavity is relatively low, which is more conducive to reducing the heating energy consumption of the battery thermal management device in the above-mentioned condition 2.

[0071] It should be noted that if the extension direction of the heat pipe is perpendicular to the height direction, the rate at which heat is conducted from the part of the heat pipe located inside the accommodating cavity to the part outside the accommodating cavity is almost the same as the rate at which heat is conducted from the part of the heat pipe located outside the accommodating cavity to the part inside the accommodating cavity.

[0072] The following content of this article is mainly described by taking the example that at least part of the structure of the heat pipe extends along the height direction.

[0073] Optionally, see Figure 8 As shown, the liquid level sensor 4 includes a second liquid level sensing portion 4b, which is used to detect the liquid level at the second position 11b, and the second liquid level sensing portion 4b is arranged on the inner surface of the top wall of the housing 1.

[0074] In other embodiments (not shown in the figures), the second liquid level sensor may also be arranged at the highest position in the portion of the heat pipe located in the accommodating cavity.

[0075] It should be noted that the liquid level sensor may include a first sub-liquid level sensor and a second sub-liquid level sensor, the first sub-liquid level sensor and the second sub-liquid level sensor are separately arranged, and the first sub-liquid level sensor includes Figure 8 The first liquid level sensor 4a shown in the figure, the second sub-liquid level sensor includes Figure 8 The second liquid level sensing portion 4b is shown.

[0076] Among them, at least one of the first sub-liquid level sensor and the second sub-liquid level sensor can be a contact liquid level sensor, and the sensing part of the contact liquid level sensor can generate a feedback signal by physically contacting the immersion liquid. In detail, when the sensing part contacts the immersion liquid, the sensing part can generate at least one feedback signal among a hydraulic signal, a resistance signal, a capacitance signal and an inductance signal. Of course, at least one of the first sub-liquid level sensor and the second sub-liquid level sensor may also be a non-contact liquid level sensor. The sensing portion of the non-contact liquid level sensor may generate a feedback signal without physically contacting the immersion liquid. Specifically, at least one ranging principle among the ultrasonic ranging principle, the infrared ranging principle and the laser ranging principle may be used to detect changes in the liquid level height of the immersion liquid, thereby generating a feedback signal.

[0077] In other embodiments, please refer to Fig. 9 As shown, the liquid level sensor 4 can be an integrated liquid level sensor located in the accommodating cavity 11, and the integrated liquid level sensor has a first liquid level sensing portion 4a and a second liquid level sensing portion 4b. Each sensing portion of the integrated liquid level sensor can generate a feedback signal by physically contacting the immersion liquid. Among them, the integrated liquid level sensor can be arranged on the side wall of the shell, or the integrated liquid level sensor can be suspended on the top wall of the shell.

[0078] In other embodiments (not shown in the figures), the liquid level sensor may include a liquid level sensing portion, which can detect liquid levels at at least two different height positions. The liquid level sensor can generate a feedback signal by a method other than physical contact with the immersion liquid, for example, by using at least one of acoustic ranging, infrared ranging and laser ranging to generate a feedback signal.

[0079] The following content of this article mainly focuses on Figure 8 The liquid level sensor 4 shown is described as an example.

[0080] Optionally, see Fig.10 As shown, the battery pack further includes a vent valve 7, which is disposed through the housing 1 and is used to circulate gas between the accommodating chamber 11 and the outside of the accommodating chamber 11. In detail, when the liquid level of the immersion liquid 20 increases, the gas in the accommodating chamber 11 can be discharged to the outside of the accommodating chamber 11 through the vent valve 7, and when the liquid level of the immersion liquid 20 decreases, the gas outside the accommodating chamber 11 can enter the accommodating chamber 11 through the vent valve 7 to balance the pressure difference between the air pressure in the accommodating chamber 11 and the air pressure outside the accommodating chamber 11.

[0081] The vent valve 7 may be disposed through the top wall of the housing 1. In other embodiments (not shown in the figures), the vent valve may also be disposed through the side wall of the housing.

[0082] Optionally, refer to Fig.11 As shown, if the vent valve 7 is disposed through the top wall of the shell 1, the inner surface of the top wall of the shell 1 may include a gas collecting slope 12, a portion of the gas collecting slope 12 is located at a higher position, and the vent valve 7 is disposed at a higher position in the gas collecting slope 12. Under this arrangement, when the liquid level of the immersion liquid 20 increases, the gas in the accommodation chamber 11 may gather toward the vent valve 7 along the gas collecting slope 12 and be discharged to the outside of the accommodation chamber 11 through the vent valve 7, thereby reducing the possibility of a large amount of gas remaining in the accommodation chamber 11, so that the immersion liquid 20 can be fully contained in the accommodation chamber 11, so that the immersion liquid 20 is fully in contact with the heat pipe, and the heat exchange efficiency between the immersion liquid 20 and the heat pipe is sufficiently large.

[0083] Please refer to Fig.11 As shown, the inner surface of the top wall of the housing 1 may include at least two gas collecting inclined surfaces 12 arranged opposite to each other in the direction X, and the vent valve 7 is located between the higher parts of the two gas collecting inclined surfaces 12 .

[0084] In other embodiments (not shown in the figures), the inner surface of the top wall of the housing may include a gas collecting slope.

[0085] It should be noted that the vent valve 7 can also have the function of preventing the immersion liquid 20 from flowing out of the accommodating cavity 11 through the vent valve 7. The principle of the vent valve 7 can refer to the principle of a waterproof breathable valve, which will not be described in detail here.

[0086] It should be noted that the housing may be provided with a first liquid port (not shown in the figure) and a second liquid port (not shown in the figure), and the immersion liquid in the accommodating chamber may flow to the outside of the accommodating chamber through the first liquid port, and the immersion liquid outside the accommodating chamber may flow back to the accommodating chamber through the second liquid port after secondary heat exchange with the heat exchange device. When the flow rate of the first liquid port is less than the flow rate of the second liquid port, the liquid level of the immersion liquid in the accommodating chamber will increase, when the flow rate of the first liquid port is greater than the flow rate of the second liquid port, the liquid level of the immersion liquid in the accommodating chamber will decrease, and when the flow rate of the first liquid port is equal to the flow rate of the second liquid port, the liquid level of the immersion liquid in the accommodating chamber remains unchanged. Therefore, the control device mentioned above (for adjusting the liquid level of the immersion liquid in the accommodating chamber) may include a flow valve, a driving pump, or other fluid devices that can affect the flow rate, and by adjusting the flow parameters of the flow valve, the flow parameters of the driving pump, or the flow parameters of other fluid devices, the flow rate of the first liquid port and the flow rate of the second liquid port are adjusted, thereby adjusting the liquid level of the immersion liquid in the accommodating chamber.

[0087] In other embodiments, please refer to Fig.12 As shown, the battery pack may include an air bag 8 disposed in the accommodating cavity, and the battery pack may also include a vent valve (not shown in the figure) penetrating the air bag 8, and the air bag 8 may be located at the side of the accommodating cavity. In other embodiments (not shown in the figure), the air bag may also be located at the lower part of the accommodating cavity.

[0088] Please refer to Fig.12 As shown, when the liquid level of the immersion liquid 20 needs to be lowered, the gas in the airbag 8 can be discharged to the outside of the airbag 8 through the vent valve, that is, the gas in the airbag 8 can enter the accommodating cavity. Fig.13 As shown, the space occupied by the airbag 8 inside the accommodating chamber 11 is reduced, and the liquid level of the immersion liquid 20 is reduced.

[0089] Please refer to Fig.13 As shown, when the liquid level of the immersion liquid 20 needs to be increased, the gas outside the airbag 8 can enter the airbag 8 through the vent valve, that is, the gas in the accommodating cavity can enter the airbag 8. Fig.12 As shown, the space occupied by the airbag 8 inside the accommodating chamber increases, and the liquid level height of the immersion liquid 20 increases.

[0090] Therefore, when it comes to Fig.12 He Ru Fig.13In the illustrated embodiment, the housing 1 may not be provided with a vent valve, the gas in the accommodating chamber 11 may not be exchanged with the gas outside the accommodating chamber 11, the gas in the accommodating chamber 11 is not easily aged by substances outside the accommodating chamber 11 (such as oxygen, water and other oxidizing substances), the thermal conductivity of the immersion liquid 20 is still good, and the immersion liquid 20 is not easily mixed with particulate impurities or water, and the insulation of the immersion liquid 20 is still good.

[0091] It should be noted that the structure for expanding or contracting the airbag 8 may include the following settings: Setting 1: A fluid pump (not shown in the figure) can be connected to the ventilation valve and be located inside the airbag 8. The fluid pump is used to actively extract the gas in the airbag 8 to discharge the gas to the outside of the airbag 8 through the ventilation valve, or the fluid pump is used to extract gas from the accommodating cavity through the ventilation valve to pump the gas into the airbag 8.

[0092] Setting 2: A driving assembly (not shown in the figure) can be connected to the outer surface of the airbag 8. The driving assembly can pull the airbag 8 to generate negative pressure inside the airbag 8, so that the airbag 8 inhales the gas in the accommodating chamber through the ventilation valve. The driving assembly can push the airbag 8 to generate positive pressure inside the airbag 8, so that the gas in the airbag 8 is discharged into the accommodating chamber through the ventilation valve.

[0093] Therefore, the control device mentioned above (for adjusting the liquid level height of the immersion liquid in the containing chamber) may include an airbag, a ventilation valve penetrating the airbag and a fluid pump, or the control device mentioned above (for adjusting the liquid level height of the immersion liquid in the containing chamber) may include an airbag, a ventilation valve penetrating the airbag and a drive assembly.

[0094] In involving Fig.12 He Ru Fig.13 In the illustrated embodiment, the flow rate of the first liquid port and the flow rate of the second liquid port may be the same, that is, the liquid level of the immersion liquid 20 may be changed by expanding or contracting the airbag 8 without changing the flow rate. In other embodiments, the liquid level of the immersion liquid 20 may also be changed in a coordinated manner by expanding or contracting the airbag 8 while changing the flow rate. In involving Fig.12 He Ru Fig.13 In the embodiment shown, the gas in the containing chamber 11 and the gas in the air bag 8 may mainly include inert gas, which is chemically inactive and can reduce the possibility of aging of the immersion liquid by the gas. Specifically, the inert gas may include nitrogen or helium.

[0095] In other embodiments, please refer to Fig.14As shown, the shell 1 may further include a partition 13. At least a first accommodating chamber 111 and a second accommodating chamber 112 are provided in the shell 1. The first accommodating chamber 111 and the second accommodating chamber 112 are separated by the partition 13. The battery cell 2 is located in the first accommodating chamber 111. The heat pipe 3 extends from the first accommodating chamber 111 to the outside of the shell 1. The sensing part of the liquid level sensor is also located in the first accommodating chamber 111. The first accommodating chamber 111 and the second accommodating chamber 112 may both be used to accommodate immersion liquid 20. At the same time, the first accommodating chamber 111 and the second accommodating chamber 112 may both be used to accommodate gas. The battery pack may further include a fluid pump (not shown in the figure) that is disposed through the partition 13. When the immersion liquid 20 in the battery pack is in a state as shown in the figure, the fluid pump 111 may be provided in the first accommodating chamber 111. Fig.14 In the state shown, the fluid pump can pump the immersion liquid 20 in the second accommodating chamber 112 into the first accommodating chamber 111 to increase the liquid level of the immersion liquid 20 in the first accommodating chamber 111, and correspondingly reduce the liquid level of the immersion liquid 20 in the second accommodating chamber 112. When the liquid level of the immersion liquid 20 in the first accommodating chamber 111 increases, the contact area between the immersion liquid 20 in the first accommodating chamber 111 and the heat pipe 3 also increases. When the immersion liquid 20 in the battery pack is in the state shown, the fluid pump can pump the immersion liquid 20 in the second accommodating chamber 112 into the first accommodating chamber 111 to increase the liquid level of the immersion liquid 20 in the first accommodating chamber 111, and correspondingly reduce the liquid level of the immersion liquid 20 in the second accommodating chamber 112. Fig.15 In the state shown, the fluid pump can pump the immersion liquid 20 in the first accommodating chamber into the second accommodating chamber 112 to reduce the liquid level of the immersion liquid 20 in the first accommodating chamber, and correspondingly increase the liquid level of the immersion liquid 20 in the second accommodating chamber 112. When the liquid level of the immersion liquid 20 in the first accommodating chamber decreases, the contact area between the immersion liquid 20 in the first accommodating chamber and the heat pipe 3 is also reduced.

[0096] Among them, the partition 13 can be provided with a breathable valve (not shown in the figure). When the liquid level of the immersion liquid 20 in the first accommodating chamber 111 increases, the gas in the first accommodating chamber 111 can enter the second accommodating chamber 112 through the breathable valve. When the liquid level of the immersion liquid 20 in the first accommodating chamber 111 decreases, the gas in the second accommodating chamber 112 can enter the first accommodating chamber 111 through the breathable valve.

[0097] It should be noted that the air valve provided on the partition 13 may have a function other than that for the immersion liquid 20 to pass through. The principle of the air valve may refer to the principle of a waterproof air valve, which will not be described in detail here.

[0098] In other embodiments (not shown in the figures), a ventilation hole may be provided on the top of the partition, and the ventilation hole is used for exchanging gas between the first accommodating chamber and the second accommodating chamber.

[0099] Therefore, the control device mentioned above (for adjusting the liquid level of the immersion liquid in the containing chamber) may include a fluid pump and a breathable valve penetrating the partition.

[0100] In involving Fig.14 He Ru Fig.15In the illustrated embodiment, the first liquid port (not shown in the figure) and the second liquid port (not shown in the figure) are both connected to the first accommodating chamber. The flow rate of the first liquid port and the flow rate of the second liquid port can be the same, that is, the liquid level of the immersion liquid in the first accommodating chamber can be changed by transferring the immersion liquid between the first accommodating chamber and the second accommodating chamber without changing the flow rate.

[0101] In involving Fig.14 He Ru Fig.15 In the illustrated embodiment, the gas in the first accommodating chamber 111 and the gas in the second accommodating chamber 112 may mainly include an inert gas, which is chemically inactive and can reduce the possibility of aging of the immersion liquid by the gas. Specifically, the inert gas may include nitrogen or helium.

[0102] In involving Fig.14 He Ru Fig.15 In the illustrated embodiment, the battery pack does not include a vent valve that penetrates the shell 1 and communicates with the outside of the shell 1. Therefore, the gas in the first accommodating chamber 111 and the gas in the second accommodating chamber 112 are not exchanged with the gas outside the shell 1, thereby reducing the possibility of the gas in the first accommodating chamber 111 and the gas in the second accommodating chamber 112 being aged by substances outside the shell 1 (such as oxygen, water and other oxidizing substances). The thermal conductivity of the immersion liquid 20 is still good, and the immersion liquid 20 is not easily mixed with particulate impurities or water, and the insulation of the immersion liquid 20 is still good.

[0103] Optionally, see Fig.16 As shown, the heat pipe 3 may include a first heat exchange part 31 and a second heat exchange part 32, the first heat exchange part 31 is located in the accommodating cavity of the shell, the second heat exchange part 32 is located outside the accommodating cavity, and the connection between the first heat exchange part 31 and the second heat exchange part 32 is passed through the shell of the battery pack.

[0104] Please refer to Fig.16 As shown, since the height of the first heat exchange part 31 is lower than that of the second heat exchange part 32, heat is more easily transferred from the first heat exchange part 31 to the second heat exchange part 32. Therefore, the first heat exchange part 31 can be an evaporation part, and the second heat exchange part 32 can be a condensation part.

[0105] Also, please refer to Fig.16 As shown, the first heat exchange part 31 may include a spiral coil structure. Under this arrangement, when the first heat exchange part 31 is in full contact with the immersion liquid, the contact area between the first heat exchange part 31 and the immersion liquid is large, and accordingly, the heat exchange efficiency between the first heat exchange part 31 and the immersion liquid is high. In other embodiments (not shown in the figure), the first heat exchange part may also include at least one of an S-shaped structure, an N-shaped structure, a Z-shaped structure, and an M-shaped structure.

[0106] Furthermore, please refer to Fig.16 As shown, the second heat exchange portion 32 may include a linear structure.

[0107] In addition, please refer to Fig.16 As shown, the heat pipe 3 may include two second heat exchange parts 32 , and a single first heat exchange part 31 is connected to the two second heat exchange parts 32 .

[0108] In other embodiments (not shown), if Fig.16 Based on the structure shown, the extension direction of the second heat exchange part is perpendicular to the height direction, and the height of the second heat exchange part is close to the height of the first heat exchange part. When the first heat exchange part is an evaporation part, the second heat exchange part can be a condensation part, and when the first heat exchange part is a condensation part, the second heat exchange part can be an evaporation part.

[0109] Optionally, see Fig.17 As shown, the battery pack further includes a plurality of heat exchange sheets 5, the heat exchange sheets 5 are located outside the accommodating cavity 11, and the portion of the heat pipe 3 located outside the accommodating cavity 11 (for example Fig.16 The second heat exchange part 32 in the heat pipe 3 is connected to the plurality of heat exchange fins 5. When the portion of the heat pipe 3 located outside the accommodating cavity 11 is used to dissipate heat outside the accommodating cavity 11, the portion of the heat pipe 3 located outside the accommodating cavity 11 can transfer heat to the plurality of heat exchange fins 5. The heat dissipation area of ​​the plurality of heat exchange fins 5 is large and the heat dissipation efficiency is high. When the portion of the heat pipe 3 located outside the accommodating cavity 11 absorbs heat outside the accommodating cavity 11 through the plurality of heat exchange fins 5, the heat absorption area of ​​the plurality of heat exchange fins 5 is large and the heat absorption efficiency is high.

[0110] Optionally, see Fig.17 As shown, the battery pack further includes a fan 6, which is used to accelerate the flow rate of the airflow around the portion of the heat pipe 3 located outside the accommodating cavity 11 and the flow rate of the airflow around the heat exchange plate 5 to improve the heat exchange efficiency.

[0111] Please refer to Fig.17 As shown, the portion of the heat pipe 3 located outside the accommodating cavity 11 (for example Fig.16 The second heat exchange portion 32 in the embodiment may be provided with a plurality of heat exchange fins 5 spaced apart in the height direction (a direction parallel to the direction Y).

[0112] Optionally, see Fig.17 As shown, the heat pipe 3 is located above the battery cell 2. When the liquid level of the immersion liquid is lower than the bottom of the heat pipe 3, the immersion liquid can also completely immerse the battery cell 2, so that the immersion liquid and the battery cell 2 can have good heat exchange in condition one or condition two.

[0113] Optionally, the external structure of the battery pack is as follows Fig.18As shown, the housing 1 is provided with a first liquid port 14a and a second liquid port 14b, the first liquid port 14a and the second liquid port 14b are connected to the accommodating cavity in the housing 1, and a plurality of fans 6 and a plurality of heat dissipation fins 5 are installed on the top of the housing 1.

[0114] Optionally, the shell may include a first structural member and a second structural member, the first structural member includes an integrally formed bottom wall and side walls, the first structural member is provided with a accommodating cavity and an opening, the second structural member includes a top wall, the second structural member covers the opening, and the first structural member and the second structural member are sealingly connected to seal the accommodating cavity.

[0115] Optionally, the battery pack may include a first temperature sensor and a second temperature sensor, wherein the first temperature sensor is used to detect the temperature of the immersion liquid in the battery pack, and the second temperature sensor is used to detect the temperature of the gas outside the battery pack. The first temperature sensor and the second temperature sensor are used to measure the relationship between the temperature of the immersion liquid in the battery pack and the temperature of the gas outside the battery pack, which serves as one of the bases for whether to adjust the liquid level of the immersion liquid.

[0116] In other embodiments, the battery pack may include a first temperature sensor located inside the battery pack for detecting the temperature of the immersion liquid in the battery pack, and a second temperature sensor for detecting the temperature of the gas outside the battery pack may be independently disposed outside the battery pack.

[0117] It should be noted that the control device mentioned above (for adjusting the liquid level of the immersion liquid) may include a control circuit, which may be electrically connected to the liquid level sensor, the temperature sensor, and the fluid. Alternatively, the control circuit may be electrically connected to the liquid level sensor, the temperature sensor, and the drive assembly for pushing or compressing the airbag.

[0118] In a second aspect, an embodiment of the present application provides an energy storage device, which includes the battery pack described above. Accordingly, the energy storage device also includes the technical effects described above, which will not be repeated here.

[0119] In some embodiments, the energy storage device also includes a container and a drive pump. In the above-mentioned condition one, condition two or condition three, the drive pump can be used to drive the immersion liquid to flow from the battery pack to the container to reduce the liquid level of the immersion liquid in the battery pack cavity, so that the heat exchange efficiency between the immersion liquid heat pipes is low, thereby reducing the working energy consumption of the battery thermal management device. When it is necessary to use the immersion liquid to exchange heat with the gas outside the battery pack through the heat pipe, the drive pump can be used to drive the immersion liquid from the container to the battery pack to increase the liquid level of the immersion liquid in the battery pack cavity, so that the heat exchange efficiency between the immersion liquid and the heat pipe is high.

[0120] Among them, Fig.19 As shown, the driving pump 30 may be a pump dedicated to making the immersion liquid flow between the battery pack 10 and the container 40, and the pipeline between the battery pack 10 and the container 40 may be a dedicated pipeline. Accordingly, other dedicated pipelines and other dedicated driving pumps may be provided between the battery pack 10 and the battery thermal management device 50.

[0121] The pipeline between the battery pack 10 and the container 40 may also be provided with an on-off valve (not shown in the figure), which is used to control the pipeline between the battery pack 10 and the container 40 to be in a flow state or a blocking state.

[0122] In addition, since the energy storage device may include multiple battery packs, each battery pack may correspond to a dedicated driving pump and a dedicated container, so as to individually control the liquid level height of the immersion liquid of different battery packs.

[0123] In other embodiments, please refer to Fig. 20 As shown, the energy storage device may include the battery thermal management device 50 mentioned above, and the battery thermal management device 50 may include a drive pump 30 and a container 40. The drive pump 30 is used to make the immersion liquid flow between the battery pack 10 and the battery thermal management device 50, and the drive pump 30 is also used to make the immersion liquid flow between the battery pack 10 and the container 40.

[0124] In detail, the energy storage device may include two drive pumps dedicated to the same battery pack. If the energy storage device includes more than two battery packs, each battery pack corresponds to two dedicated drive pumps. Taking one of the battery packs as an example, one dedicated drive pump is used to pump the immersion liquid in the container into the battery pack, and the other dedicated drive pump is used to pump the immersion liquid in the battery pack into the container. The pumping flow rate of one dedicated drive pump and the pumping flow rate of the other dedicated drive pump may be different, so that the liquid level height of the immersion liquid in the battery pack changes, and accordingly, the liquid level height of the immersion liquid in the container also changes. If the flow rate of the immersion liquid entering the battery pack is greater than the flow rate of the immersion liquid flowing out of the battery pack, the liquid level height of the immersion liquid in the battery pack increases, and the liquid level height of the immersion liquid in the container decreases. If the flow rate of the immersion liquid entering the battery pack is less than the flow rate of the immersion liquid flowing out of the battery pack, the liquid level height of the immersion liquid in the battery pack decreases, and the liquid level height of the immersion liquid in the container increases. If the flow rate of the immersion liquid entering the battery pack is equal to the flow rate of the immersion liquid flowing out of the battery pack, the liquid level height of the immersion liquid in the battery pack remains unchanged, and the liquid level height of the immersion liquid in the container also remains unchanged.

[0125] In other embodiments, if the battery pack included in the energy storage device is related to Figure 12-13 In the embodiment shown, or if the battery pack included in the energy storage device is related to Figure 14-15In the embodiment shown, that is, the battery pack is provided with a control device capable of adjusting the liquid level of the immersion liquid, the energy storage device may not include a container and a drive pump located outside the battery pack.

[0126] In some embodiments, the energy storage device also includes the battery compartment and gas thermal management equipment described above, and the relevant specific contents are not repeated here.

[0127] Accordingly, the energy storage device may also include a battery management system (BMS), an inverter and other auxiliary electrical equipment (not shown in the figure) to assist in completing the charging and discharging work.

[0128] Among them, the battery management system is used to monitor the voltage, current and temperature of the battery cells. The battery management system is also used to control the voltage and current of the battery cells. The battery management system is also used for self-diagnosis and fault recording.

[0129] The inverter is used to convert direct current into alternating current. The inverter has the advantages of high conversion efficiency, fast startup speed, high safety, etc. It also has the functions of short circuit, overload, over / under voltage and over-temperature protection.

[0130] Optionally, the energy storage device may specifically be an energy storage box (also known as a large energy storage device, suitable for technical fields such as large-scale industrial production or power distribution).

[0131] Optionally, the energy storage device may specifically be an energy storage cabinet (also known as an industrial and commercial energy storage device, suitable for small-scale industrial and commercial electricity needs).

[0132] In a third aspect, with respect to the energy storage device described above, an embodiment of the present application provides a control method for the energy storage device, the method comprising: The energy storage device is placed in the first state or the second state. It should be noted that in the above-described condition 1, condition 2 or condition 3, the energy storage device can be placed in the first state, and in the above-described condition "when it is necessary to use the immersion liquid to exchange heat with the gas outside the battery pack through the heat pipe", the energy storage device can be placed in the second state.

[0133] In the first state, the liquid level of the immersion liquid in the battery pack is lowered, and the liquid level of the immersion liquid is detected by the liquid level sensor. When the liquid level of the immersion liquid is less than or equal to the height of the first position, the operation of "lowering the liquid level of the immersion liquid in the battery pack" is stopped, that is, the liquid level of the immersion liquid in the battery pack is kept unchanged. Under this setting, the contact area between the immersion liquid and the heat pipe is relatively small, the heat exchange efficiency between the immersion liquid and the heat pipe is low, and the working energy consumption of the battery thermal management device is relatively low.

[0134] In the second state, the liquid level of the immersion liquid in the battery pack is increased, and the liquid level of the immersion liquid is detected by the liquid level sensor. When the liquid level of the immersion liquid is greater than or equal to the height of the second position, the operation of "increasing the liquid level of the immersion liquid in the battery pack" is stopped, that is, the liquid level of the immersion liquid in the battery pack is kept unchanged. Under this setting, the contact area between the immersion liquid and the heat pipe is relatively large, and the heat exchange efficiency between the immersion liquid and the heat pipe is high, which can better meet the needs of improving the heat dissipation efficiency or heating efficiency of the battery cell.

[0135] Optionally, in a first state, a driving pump is used to extract a portion of the immersion liquid in the battery pack to lower the height of the immersion liquid in the battery pack, so that the vent valve of the battery pack is in a vent state, so that gas outside the battery pack can enter the battery pack; in a second state, a driving pump is used to replenish the immersion liquid in the battery pack to increase the height of the immersion liquid in the battery pack, so that the vent valve of the battery pack is in a vent state, so that gas in the battery pack can be discharged to the outside of the battery pack.

[0136] The vent valve can be an electromagnetic control valve or a pressure valve. If the vent valve is an electromagnetic control valve, the control device mentioned above can include the vent valve, and the control circuit can control whether the vent valve is in a closed state or a ventilating state. If the vent valve is a pressure valve, when the pressure difference on both sides of the vent valve is greater than a set value, the vent valve is in a ventilating state, and when the pressure difference on both sides of the vent valve is less than a set value, the vent valve is in a closed state.

[0137] The specific method for changing the liquid level of the immersion liquid in the battery pack has been described in detail above and will not be repeated here.

[0138] The above description is only the preferred 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 modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery pack, characterized in that: The battery pack includes a housing, a battery cell, a heat pipe and a liquid level sensor; The housing is provided with a receiving cavity, the receiving cavity is used to receive the immersion liquid, and at least one of the battery cells is arranged in the receiving cavity; The heat pipe extends from the inside of the accommodating cavity to the outside of the accommodating cavity; The liquid level sensor is used to detect the liquid level at a first position in the accommodating cavity, and the height of at least a portion of the structure of the portion of the heat pipe located in the accommodating cavity is greater than the height of the first position.

2. The battery pack according to claim 1, characterized in that: The height of the first position is less than or equal to the height of the bottom of the portion of the heat pipe located in the accommodating cavity.

3. The battery pack according to claim 2, characterized in that: The liquid level sensor comprises a first liquid level sensing portion, and the first liquid level sensing portion is used to detect the liquid level at the first position; The first liquid level sensor is arranged at the bottom of the portion of the heat pipe located in the accommodating cavity.

4. The battery pack according to any one of claims 1 to 3, characterized in that: The liquid level sensor is further used to detect the liquid level at a second position in the accommodating chamber, and the height of the second position is greater than the height of the first position.

5. The battery pack according to claim 4, characterized in that: The heat pipe is disposed through the top wall of the shell, and the height of the second position is the same as the height of the highest position in the accommodating cavity.

6. The battery pack according to claim 5, characterized in that: The liquid level sensor comprises a second liquid level sensing portion, and the second liquid level sensing portion is used to detect the liquid level at the second position; The second liquid level sensor is arranged on the inner surface of the top wall of the shell.

7. The battery pack according to any one of claims 1 to 3, characterized in that: The battery pack further includes a vent valve, which is disposed through the shell and is used for gas to flow between the inside of the accommodating cavity and the outside of the accommodating cavity.

8. An energy storage device, characterized in that: The energy storage device comprises a battery pack, a container and a driving pump, wherein the battery pack is the battery pack according to any one of claims 1 to 7, and the container is used to contain an immersion liquid; The driving pump is used to drive the immersion liquid to flow from the battery pack to the container, so as to reduce the liquid level of the immersion liquid in the battery pack.

9. A control method for an energy storage device, characterized in that: The control method of the energy storage device comprises: enabling the energy storage device to be in at least a first state; In the first state, the liquid level of the immersion liquid in the battery pack is lowered, and the liquid level of the immersion liquid is detected by a liquid level sensor. When the liquid level of the immersion liquid is less than or equal to the height of the first position, the lowering of the liquid level of the immersion liquid in the battery pack is stopped.

10. The control method of the energy storage device according to claim 9, characterized in that: In the first state, at least a portion of the immersion liquid in the battery pack is pumped out by a driving pump, so that the vent valve of the battery pack is in a venting state, so that the gas outside the battery pack can enter the battery pack.

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