Immersion spray type battery pack and battery pack thermal runaway control method

Abstract

The present invention relates to the field of battery technology, and discloses an immersion spray type battery pack and a method for controlling thermal runaway of a battery pack, comprising a lower box, an upper cover arranged on the upper side of the lower box, and a battery module, wherein the lower box is provided with a liquid inlet and a liquid outlet connected to the interior of the lower box; the battery module is placed inside the lower box; the interior of the lower box is injected with coolant from the liquid inlet and discharged from the liquid outlet, and the coolant level inside the lower box is higher than the upper side of the battery module. When in use, the coolant is injected into the interior of the lower box through the liquid inlet, and the coolant level inside the lower box is higher than the upper side of the battery module, that is, the entire battery module is submerged in the coolant, and the coolant after absorbing heat is discharged from the interior of the lower box through the liquid outlet, and the cycle is thus realized to cool down the battery module. In addition, an electromagnetic puncture valve is arranged on the side wall of the battery pack box, and after thermal runaway, the valve can be opened to allow the coolant to flow into the inner cavity to spray and extinguish the thermal runaway flame.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to an immersion spray type battery pack and a battery pack thermal runaway control method. Background Art

[0002] With the rapid development of new energy technologies, people have higher and higher requirements on battery systems, and at the same time, they have also put forward higher requirements on the safety performance of battery systems.

[0003] Energy storage batteries generate a lot of heat during the charging and discharging process due to the presence of ohmic heat and polarization heat. If this heat cannot be diffused in time, on the one hand, it will accumulate inside the battery and increase the rate of the side reactions at the interface of the energy storage battery. On the other hand, excessive heat accumulation may cause thermal runaway of the battery. At present, there are two main heat dissipation methods for energy storage systems: air cooling and liquid cooling. Air cooling mainly uses air conditioning for cooling, and the cooling medium is air. Liquid cooling uses a cooling plate with coolant as the cooling medium, and heat is exchanged between the cooling medium flowing in the cooling plate and the energy storage battery. At present, common battery packs on the market are all in the form of liquid-cooled bottom plates for bottom heat dissipation of the battery cells. However, this heat dissipation method not only has low heat dissipation efficiency, but also cannot maintain temperature uniformity between battery packs, which may cause the overall life of the battery cluster to decay too quickly. Summary of the invention

[0004] In view of this, the present invention provides an immersion spray type battery pack to solve the problem of low heat dissipation efficiency of the current liquid cooling base plate heat dissipation method.

[0005] In a first aspect, the present invention provides an immersion spray type battery pack, comprising:

[0006] A lower box body and an upper cover arranged on the upper side of the lower box body, wherein the lower box body is provided with a liquid inlet and a liquid outlet communicating with the interior of the lower box body;

[0007] A battery module is placed inside the lower box;

[0008] Wherein, coolant is injected into the lower box body through the liquid inlet and discharged from the liquid outlet, and the coolant level inside the lower box body is higher than the upper side of the battery module.

[0009] In an optional embodiment, the lower box includes:

[0010] A lower box shell and a lower box bottom plate fixed to the bottom of the lower box shell, wherein a placement cavity is formed between the lower box shell and the lower box bottom plate;

[0011] The lower box inner shell is fixedly installed inside the placement cavity, and the side edge of the lower box inner shell is sealed and fixed to the side edge of the lower box outer shell, so as to form a cooling cavity between the cavity wall of the placement cavity and the outer wall of the lower box inner shell; the cooling cavity is connected with the liquid inlet and the liquid outlet;

[0012] A flow channel partition plate is fixed in the cooling cavity.

[0013] In the above structure, the inner shell of the lower box body is a cast aluminum box body, the interior of the box body is sealed and integrally cast with bolt mounting holes, which can facilitate the installation of components such as battery modules and power distribution units. The outer shell of the lower box body is an aluminum profile welded box body. The aluminum profile is formed into a ring shape through a bending process. The bottom is sealed with the bottom plate of the lower box body by stir friction welding, and the box body support beam and flow channel partition plate are welded inside to form the entire outer box. The inner shell of the lower box body is embedded in the lower box body outer shell as a whole, so that a cooling cavity is formed between the two shells, which is the coolant space. The lower box body of the battery pack adopts a stacked basin design: the inner shell of the lower box body is a cast aluminum box body, and the outer box is an aluminum profile welded box body. The inner shell of the lower box body is embedded in the lower box body outer shell as a whole, so that a cavity area is formed between the two shells, which is the coolant space. The coolant can exchange heat with the bottom and surroundings of the battery pack, increasing the heat dissipation area of ​​the battery pack.

[0014] In an optional embodiment, the liquid outlet is arranged at a height that is at least 3 mm greater than the height of the upper side of the battery module.

[0015] In the above structure, after the battery pack is filled with liquid, the entire inner cavity of the battery pack is immersed in the coolant. In this way, the battery pack can not only exchange heat at the bottom, but also exchange heat through the shell on all sides. The coolant liquid level is higher than the top of the module CCS, and the height difference is h>3mm; this can ensure that the coolant immerses the battery module after thermal runaway. The liquid inlet of the battery pack is located at the bottom of the battery pack, and the liquid outlet is close to the coolant liquid level, that is, the height of the liquid outlet is set at least 3mm greater than the height of the upper side of the battery module. In this way, the coolant can fill the entire flow channel as much as possible.

[0016] In an optional embodiment, the lower box body further includes a box body support beam, the box body support beam is fixed in the lower box body outer shell, and the box body support beam adopts a hollow structure.

[0017] In the above structure, a flow channel partition is set in the middle of the box to form a unique flow channel trend. On the one hand, the coolant flows around the lower box inner shell from the side of the box and then flows out of the liquid outlet; on the other hand, the coolant flows through the hollow position of the bottom box support beam, passes through the tail of the box, and then goes back to the liquid outlet, which can ensure the uniformity of the flow channel and the temperature uniformity performance.

[0018] In an optional embodiment, the side of the lower box inner shell is bent outward and placed in a step groove on the side of the lower box outer shell. The step groove on the side of the lower box outer shell is provided with a glue groove, and a glue overflow groove and a bolt hole are arranged near the glue groove.

[0019] In the above structure, the two shells of the lower box are sealed by a sealing layer, and a glue overflow groove and a bolt hole are provided near the glue groove. After applying the glue, bolts are used to lock them to ensure the sealing requirements of the inner and outer boxes. The bottom of the lower box shell is stir friction welded, and sealant is also required after welding. The same method is used for the other welding positions to avoid the risk of welding leakage.

[0020] In an optional embodiment, the upper cover is provided with an explosion-proof valve communicating with the interior of the lower box body, high and low pressure connectors, and a BMS controller electrically connected to the high and low pressure connectors.

[0021] In the above structure, the explosion-proof valve and the BMS controller are arranged on the top of the upper cover; this facilitates the smooth discharge of high-pressure gas in the battery pack after thermal runaway, and also prevents the coolant from entering the battery pack and causing the explosion-proof valve to be positioned too low, resulting in the top gas being unable to be discharged; at the same time, the BMS controller is located outside the battery pack, which can avoid the risk of control delay and signal loss caused by thermal runaway.

[0022] In an optional embodiment, the lower box body is further provided with:

[0023] A power distribution unit, electrically connected between the battery module and the high and low voltage connectors;

[0024] An electromagnetic puncture valve, electrically connected to the BMS controller, the electromagnetic puncture valve being fixed to the side wall of the battery module;

[0025] A fire alarm is electrically connected to the BMS controller.

[0026] In the above structure, the inner shell of the battery pack is provided with an electromagnetic puncture valve, which is located in the upper middle part of the battery pack near the water outlet. After thermal runaway, the electromagnetic puncture valve can be opened to directly spray coolant inside to control the thermal runaway of the battery pack. Compared with ordinary battery packs, it saves fire-fighting pipes, equipment, fire-extinguishing agents and other parts.

[0027] In an optional embodiment, the battery module includes:

[0028] Battery cell group;

[0029] A module CCS is provided on the upper side of the battery cell group, and the module CCS is sealed with the upper side of the battery cell group; the module CCS is electrically connected to the BMS controller;

[0030] A module upper cover is arranged on the upper side of the module CCS, and a sealing layer exists between the module upper cover and the module CCS;

[0031] Wherein, a sealing rubber ring is provided at the bottom of the module CCS and the top of each battery cell, and the sealing rubber ring covers the top component of the battery cell.

[0032] In an optional embodiment, the thickness T of the module cover in the explosion-proof valve area on the top of the battery cell is less than 0.5 mm.

[0033] In the above structure, the module cover is thinned in the explosion-proof valve area, with a thickness of T<0.5mm. This ensures that after the battery cell thermal runaway, the module cover only opens a gap at the spray valve, which can accurately control the fire situation of the battery cell.

[0034] In a second aspect, the present invention further provides a battery pack thermal runaway control method for the above-mentioned immersion spray type battery pack, comprising the following steps:

[0035] BMS determines the number of out-of-control cells:

[0036] If a single cell is out of control and the temperature is controllable, the control relay is disconnected and left to stand;

[0037] If a single battery cell is out of control and the temperature is uncontrollable, open the electromagnetic puncture valve and monitor the coolant level and battery cell temperature in the battery pack;

[0038] If multiple cells are out of control and the temperature is controllable, open the electromagnetic puncture valve and monitor the liquid level in the package and the temperature of the cells;

[0039] If multiple cells are out of control and the temperature is uncontrollable, open the electromagnetic puncture valve, close the liquid outlet, and monitor the liquid level in the battery pack;

[0040] Among them, if the battery pack is full of liquid, the liquid level alarm sends a signal and the BMS controls the liquid inlet and outlet to be closed.

[0041] The immersion spray type battery pack and the battery pack thermal runaway control method provided by the present invention have the following advantages:

[0042] 1. The present invention provides an immersion spray type battery pack, comprising a lower box body, an upper cover arranged on the upper side of the lower box body, and a battery module, wherein the lower box body is provided with a liquid inlet and a liquid outlet connected to the interior of the lower box body; the battery module is placed inside the lower box body; wherein coolant is injected into the interior of the lower box body through the liquid inlet and discharged from the liquid outlet, and the coolant level inside the lower box body is higher than the upper side of the battery module.

[0043] The submerged spray battery pack of this structure is constructed by placing the battery module inside the lower box, and the lower box is provided with a liquid inlet and a liquid outlet connected to the lower box. When in use, the coolant is injected into the lower box through the liquid inlet, and the height of the coolant inside the lower box is higher than the upper side of the battery module, that is, the entire battery module is submerged in the coolant, and the coolant after absorbing heat is discharged from the lower box through the liquid outlet, and the cycle is completed to achieve cooling of the battery module. Compared with the liquid cooling bottom plate form, the cooling method in this embodiment has high cooling efficiency and helps to maintain the uniform temperature between battery packs. Among them, the above-mentioned coolant adopts the insulating coolant in the prior art.

[0044] 2. The present invention provides an immersion spray type battery pack, wherein the lower box body comprises a lower box shell, a lower box bottom plate fixed to the bottom of the lower box shell, a lower box inner shell and a flow channel partition plate, wherein a placement cavity is formed between the lower box shell and the lower box bottom plate; the lower box inner shell is fixedly installed inside the placement cavity, and the side edge of the lower box inner shell is sealed and fixed to the side edge of the lower box shell to form a cooling cavity between the cavity wall of the placement cavity and the outer wall of the lower box inner shell; the cooling cavity is connected to the liquid inlet and the liquid outlet; and the flow channel partition plate is fixed in the cooling cavity.

[0045] The submerged spray battery pack of this structure has a cast aluminum box as the inner shell of the lower box. The box is sealed and has bolt mounting holes cast in one piece, which can facilitate the installation of components such as battery modules and power distribution units. The outer shell of the lower box is a welded box made of aluminum profiles. The aluminum profile is formed into a ring shape through a bending process. The bottom is sealed with the bottom plate of the lower box by stir friction welding. The box support beam and the flow channel partition plate are welded inside to form the entire outer box. The inner shell of the lower box is embedded in the lower box shell as a whole, so that a cooling cavity is formed between the two shells, which is the coolant space. The lower box of the battery pack adopts a stacked basin design: the inner shell of the lower box is a cast aluminum box, and the outer box is a welded box made of aluminum profiles. The inner shell of the lower box is embedded in the lower box shell as a whole, so that a cavity area is formed between the two shells, which is the coolant space. The coolant can exchange heat with the bottom and surrounding areas of the battery pack, increasing the heat dissipation area of ​​the battery pack.

[0046] 3. The present invention provides an immersion spray type battery pack, wherein the side edge of the inner shell of the lower box body is bent outward and placed in a step groove on the side edge of the outer shell of the lower box body, and a glue groove, as well as a glue overflow groove and a bolt hole are provided on the step groove on the side edge of the glue groove.

[0047] For the immersed spray-type battery pack of this structure, the two shells of the lower box are sealed by a sealing layer, and a glue overflow groove and bolt holes are provided near the glue groove. Bolts are used to lock after glue application to ensure the sealing requirements of the inner and outer boxes. The bottom of the lower box shell is stir friction welded, and sealant is also required after welding. The same method is used for the other welding positions to avoid the risk of welding leakage.

[0048] 4. The present invention provides an immersion spray type battery pack, wherein the upper cover is provided with an explosion-proof valve connected to the interior of the lower box body, a high and low voltage connector, and a BMS controller electrically connected to the high and low voltage connector.

[0049] For the immersed spray battery pack of this structure, the explosion-proof valve and BMS controller are arranged on the top of the upper cover; this facilitates the smooth discharge of high-pressure gas in the battery pack after thermal runaway, and also prevents the phenomenon in which the explosion-proof valve is positioned too low after coolant enters the battery pack, causing the top gas to be unable to be discharged; at the same time, the BMS controller is located outside the battery pack, which can avoid the risk of control delay and signal loss caused by thermal runaway.

[0050] 5. The present invention provides an immersion spraying battery pack. After the battery pack is filled with liquid, the entire inner cavity of the battery pack is immersed in the coolant. In this way, the battery pack can not only exchange heat at the bottom, but also exchange heat on all sides through the shell. The coolant liquid level is higher than the top of the module CCS, and the height difference is h>3mm; this can ensure that the coolant immerses the battery module after thermal runaway. The liquid inlet of the battery pack is located at the bottom of the battery pack, and the liquid outlet is close to the coolant liquid level, that is, the height of the liquid outlet is set to be at least 3mm greater than the height of the upper side of the battery module. In this way, the coolant can fill the entire flow channel as much as possible. The inner shell of the battery pack is provided with an electromagnetic puncture valve, which is located in the upper middle part of the battery pack near the liquid outlet. Figure 3 As shown, the circled area is the location of the electromagnetic puncture valve. After thermal runaway, the electromagnetic puncture valve can be opened to directly spray coolant inside to control thermal runaway of the battery pack.

[0051] 6. The present invention provides an immersion spray type battery pack, in which the inner shell of the battery pack is provided with an electromagnetic puncture valve, which is located in the upper middle part of the battery pack near the water outlet. After thermal runaway, the electromagnetic puncture valve can be opened to directly spray coolant inside to control the thermal runaway of the battery pack. Compared with ordinary battery packs, it saves fire-fighting pipes, equipment, fire extinguishing agents and other parts.

[0052] 7. The present invention provides an immersion spray type battery pack, in which a flow channel partition plate is arranged in the middle of the box body to form a unique flow channel trend. On the one hand, the coolant flows from the side of the box body around the lower box body inner shell and then flows out of the liquid outlet; on the other hand, the coolant flows through the hollow position of the bottom box body support beam through the tail of the box body, and then flows back to the liquid outlet, which can ensure the uniformity and temperature uniformity of the flow channel.

[0053] 8. The present invention provides a battery pack thermal runaway control method for the above-mentioned immersion spray type battery pack, comprising the following steps:

[0054] BMS determines the number of out-of-control cells:

[0055] If a single cell is out of control and the temperature is controllable, the control relay is disconnected and left to stand;

[0056] If a single battery cell is out of control and the temperature is uncontrollable, open the electromagnetic puncture valve and monitor the coolant level and battery cell temperature in the battery pack;

[0057] If multiple cells are out of control and the temperature is controllable, open the electromagnetic puncture valve and monitor the liquid level in the package and the temperature of the cells;

[0058] If multiple cells are out of control and the temperature is uncontrollable, open the electromagnetic puncture valve, close the liquid outlet, and monitor the liquid level in the battery pack;

[0059] Among them, if the battery pack is full of liquid, the liquid level alarm sends a signal and the BMS controls the liquid inlet and outlet to be closed.

[0060] The above-mentioned battery pack thermal runaway control method starts with the thermal runaway of the first battery cell in the battery pack: when the first battery cell thermally runs away, the voltage and temperature signals of the battery cell will suddenly change. At this time, the fire alarm will also send out an alarm signal after detecting the combustible gas. The signals are transmitted to the BMS controller. The BMS controller will first disconnect the relay of the power distribution unit to ensure that the battery pack is in an open circuit state. If a single battery cell is out of control and the temperature is controllable, the puncture valve does not need to be opened, and the hidden danger can be eliminated by only disconnecting the circuit and leaving it still.

[0061] If a single battery cell is out of control and the temperature is uncontrollable, the BMS will send a signal to the electromagnetic puncture valve to open it, and the coolant can flow directly into the battery pack to extinguish the internal flame. This process requires real-time monitoring of the liquid level and battery cell temperature in the battery pack. If the battery pack is full of liquid, the liquid level alarm will send a signal, and the BMS will control the liquid inlet and outlet to close to prevent the coolant from flowing back and polluting the cooling system.

[0062] If multiple battery cells are out of control and the temperature is uncontrollable, the puncture valve needs to be opened and the liquid outlet closed at the same time. The coolant can flow directly into the battery pack to extinguish the internal flame. Closing the liquid outlet can increase the speed of coolant inflow into the battery pack, making it easier for the liquid to fill the battery pack as quickly as possible to stabilize the thermal runaway situation inside the pack. If the battery pack is full of liquid, the liquid level alarm will send a signal, and the BMS will control the liquid inlet and outlet to be closed to prevent coolant from flowing back and polluting the cooling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0064] Figure 1 The figure is an appearance diagram of an immersion spray type battery pack provided in an embodiment of the present invention;

[0065] Figure 2 An exploded view of an immersion spray type battery pack provided in an embodiment of the present invention;

[0066] Figure 3 An exploded view of the lower box of the immersion spray type battery pack provided in an embodiment of the present invention;

[0067] Figure 4 A cross-sectional process diagram of a lower box in an immersion spray type battery pack provided in an embodiment of the present invention;

[0068] Figure 5 It is a schematic structural diagram of the glue tank part in the immersion spray type battery pack provided in an embodiment of the present invention;

[0069] Figure 6 A longitudinal cross-sectional view of an immersion spray type battery pack provided in an embodiment of the present invention;

[0070] Figure 7 A transverse cross-sectional view (coolant trend diagram) of an immersion spray type battery pack provided in an embodiment of the present invention;

[0071] Figure 8 An exploded view of a battery module in an immersion spray type battery pack provided in an embodiment of the present invention;

[0072] Fig. 9 It is a schematic diagram of the bottom structure of the module CCS in the immersion spray type battery pack provided in the embodiment of the present invention;

[0073] Fig.10 It is a schematic diagram of the operation process of the immersion spray type battery pack provided in the embodiment of the present invention.

[0074] Description of reference numerals:

[0075] 1-lower box; 101-lower box outer shell; 102-lower box bottom plate; 103-lower box inner shell; 104-flow channel partition plate; 105-box support beam;

[0076] 2-Upper cover;

[0077] 31-Liquid inlet; 32-Liquid outlet

[0078] 4-battery module; 401-cell group; 402-module CCS; 403-module cover; 404-sealing rubber ring; 405-glue groove; 406-glue overflow groove; 407-bolt hole; 408-end plate; 409-binding strap; 410-output pole insulation seat;

[0079] 5- Explosion-proof valve;

[0080] 6-High and low voltage connectors;

[0081] 7-BMS controller;

[0082] 8- Power distribution unit;

[0083] 9- electromagnetic puncture valve;

[0084] 10- Fire alarm. DETAILED DESCRIPTION

[0085] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0086] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0087] Example 1

[0088] With the rapid development of new energy technologies, people have higher and higher requirements on battery systems, and at the same time, they have also put forward higher requirements on the safety performance of battery systems.

[0089] Currently, the common battery packs on the market are all in the form of liquid-cooled base plates to dissipate heat from the bottom of the battery cells. However, this heat dissipation method not only has low heat dissipation efficiency, but also cannot maintain uniform temperature between battery packs, which may cause the overall life of the battery cluster to decay too quickly.

[0090] To this end, this embodiment provides an immersion spray type battery pack to solve the problem of low heat dissipation efficiency of the current liquid cooling base plate heat dissipation method.

[0091] In this embodiment, the immersion spray type battery pack includes a lower box body 1, an upper cover 2 arranged on the upper side of the lower box body 1, and a battery module 4, and the lower box body 1 is provided with a liquid inlet 31 and a liquid outlet 32 ​​connected to the interior of the lower box body 1; the battery module 4 is placed inside the lower box body 1; wherein, coolant is injected into the interior of the lower box body 1 through the liquid inlet 31 and discharged through the liquid outlet 32, and the coolant level inside the lower box body 1 is higher than the upper side of the battery module 4.

[0092] In this embodiment, the battery module 4 is placed inside the lower box 1, and the lower box 1 is provided with a liquid inlet 31 and a liquid outlet 32 ​​connected to the lower box 1. When in use, the coolant is injected into the lower box 1 through the liquid inlet 31, and the height of the coolant inside the lower box 1 is higher than the upper side of the battery module 4, that is, the entire battery module 4 is submerged in the coolant, and the coolant after absorbing heat is discharged from the lower box 1 through the liquid outlet 32, and the cycle is completed to achieve cooling of the battery module 4. Compared with the liquid cooling bottom plate form, the cooling method in this embodiment has high cooling efficiency and helps to maintain the uniform temperature between battery packs. Among them, the above-mentioned coolant adopts the insulating coolant in the prior art.

[0093] In this embodiment, the liquid inlet 31 and the liquid outlet 32 ​​of the water cooling system are respectively located at the lower left end and the upper right end of the box body, so that the coolant can fill the entire liquid cooling system.

[0094] In this embodiment, if Figures 2 to 7 As shown, the lower box body 1 includes a lower box shell 101, a lower box bottom plate 102 fixed to the bottom of the lower box shell 101, a lower box inner shell 103 and a flow channel partition plate 104, and a placement cavity is formed between the lower box shell 101 and the lower box bottom plate 102; the lower box inner shell 103 is fixedly installed inside the placement cavity, and the side edge of the lower box inner shell 103 is sealed and fixed to the side edge of the lower box shell 101 to form a cooling cavity between the wall of the placement cavity and the outer wall of the lower box inner shell 103; the cooling cavity is connected to the liquid inlet 31 and the liquid outlet 32; the flow channel partition plate 104 is fixed in the cooling cavity.

[0095] In this embodiment, the lower box body 1 further includes a box body support beam 105, which is fixed in the lower box body outer shell 101, and the box body support beam 105 adopts a hollow structure.

[0096] Specifically, the lower box body inner shell 103 is a cast aluminum box body, the inside of the box body is sealed and integrally cast with bolt mounting holes, which can facilitate the installation of components such as the battery module 4 and the power distribution unit 8 (PDU). The lower box body shell 101 is a box body welded from aluminum profiles. The aluminum profiles are formed into a ring shape through a bending process, and the bottom is sealed with the lower box body bottom plate 102 through stir friction welding. The box body support beam 105 and the flow channel partition plate 104 are welded inside to form the entire outer box. The lower box body inner shell 103 is integrally embedded in the lower box body shell 101, so that a cooling cavity is formed between the two shells, which is the coolant space.

[0097] In this embodiment, the battery pack lower box 1 adopts a stacked basin design: the lower box inner shell 103 is a cast aluminum box, and the outer box is an aluminum profile welded box. The lower box inner shell 103 is integrally embedded in the lower box outer shell 101, so that a cavity area is formed between the two shells, which is the coolant space. The coolant can exchange heat with the bottom and surrounding of the battery pack, increasing the heat dissipation area of ​​the battery pack.

[0098] The flow channel partition in this embodiment is fixed to the bottom of the lower box inner shell 103 and can also provide partial support for the lower box inner shell 103 .

[0099] In this embodiment, the side of the lower box inner shell 103 is bent outward and placed in the step groove on the side of the lower box outer shell 101. The step groove on the side of the lower box outer shell 101 is provided with a glue groove 405, and a glue overflow groove 406 and a bolt hole 407 arranged near the glue groove 405.

[0100] The difficulty of the lower box 1 in this embodiment is mainly sealing. Figure 4 and Figure 5 As shown, the two shells of the lower box 1 are sealed by a sealing layer, and a glue overflow groove 406 and a bolt hole 407 are provided near the glue groove 405. Bolts are used to lock after glue is applied to ensure the sealing requirements of the inner and outer boxes; the bottom of the lower box shell 101 is stir-friction welded, and sealant is also required after welding; the other welding positions are used in the same way to avoid the risk of welding leakage. In addition, Figure 4 In the illustrated embodiment, the box support beam 105 is of hollow design, which can increase the flow of the bottom coolant.

[0101] In this embodiment, if Figure 1 As shown, the upper cover 2 is provided with an explosion-proof valve 5 communicating with the interior of the lower box 1 , a high- and low-pressure connector 6 , and a BMS controller 7 electrically connected to the high- and low-pressure connector 6 .

[0102] The explosion-proof valve 5 and the BMS controller 7 are arranged on the top of the upper cover 2; this facilitates the smooth discharge of high-pressure gas in the battery pack after thermal runaway, and also prevents the coolant from entering the battery pack and causing the top gas to be unable to be discharged due to the low position of the explosion-proof valve 5; at the same time, the BMS controller 7 is located outside the battery pack, which can avoid the risk of control delay and signal loss caused by thermal runaway.

[0103] In this embodiment, if Figure 2 As shown, a power distribution unit 8, an electromagnetic puncture valve 9 and a fire alarm 10 are also provided inside the lower box body 1. The power distribution unit 8 is electrically connected between the battery module 4 and the high and low voltage connectors 6; the electromagnetic puncture valve 9 is electrically connected to the BMS controller 7, and the electromagnetic puncture valve 9 is fixed to the side wall of the battery module 4; the fire alarm 10 is electrically connected to the BMS controller 7.

[0104] In this embodiment, the battery module 4 is assembled and placed inside the lower box 1, connected to the power distribution unit 8 through a copper busbar, and the power distribution unit 8 is connected to the high-voltage connector, thus forming the main part of the entire battery system; the module CCS402 collects the voltage and temperature signals of the battery module 4, and is connected to the BMS controller 7 through the high and low voltage connectors 6. At the same time, the electromagnetic puncture valve 9, the power distribution unit 8, the fire alarm 10, etc. are all connected to the BMS controller 7 through corresponding connectors to form the control system part of the entire battery pack; in addition, the liquid inlet 31 and the liquid outlet 32 ​​of the battery pack can also be increased with corresponding electric control valves to control the inlet and outlet of the coolant; the power distribution unit 8 contains electrical components such as relays and fuses.

[0105] like Figure 6 As shown, Figure 6 It is a longitudinal cross-section of an immersed spray-type battery pack. After the battery pack is filled with liquid, the entire inner cavity of the battery pack is immersed in the coolant. In this way, the battery pack can not only exchange heat at the bottom, but also exchange heat on all sides through the shell. The coolant liquid level is higher than the top of the module CCS402, and the height difference is h>3mm; this can ensure that the coolant immerses the battery module 4 after thermal runaway. The liquid inlet 31 of the battery pack is located at the bottom of the battery pack, and the liquid outlet 32 ​​is close to the coolant liquid level, that is, the height of the liquid outlet 32 ​​is set greater than the upper side height of the battery module 4 by at least 3mm. In this way, the coolant can fill the entire flow channel as much as possible. The inner shell of the battery pack is provided with an electromagnetic puncture valve 9, which is located in the upper middle part of the battery pack near the liquid outlet 32. Figure 3 As shown, the circled area is the position of the electromagnetic puncture valve 9. After thermal runaway, the electromagnetic puncture valve 9 can be opened to directly spray coolant inside to control the thermal runaway of the battery pack.

[0106] The inner shell of the battery pack is provided with an electromagnetic puncture valve 9, which is located near the water outlet in the upper middle part of the battery pack. After thermal runaway, the electromagnetic puncture valve 9 can be opened to directly spray coolant inside to control the thermal runaway of the battery pack. Compared with ordinary battery packs, it saves fire-fighting pipes, equipment, fire-extinguishing agents and other parts.

[0107] like Figure 7 As shown, Figure 7 This is a cross-sectional view of an immersion spray battery pack. The flow of the coolant inside the box can be clearly seen. The inlet 31 is located at the lower left of the front of the box, and the outlet 32 ​​is located at the upper right of the front of the box. A flow channel partition plate 104 is set in the middle of the box to form a unique flow channel. On the one hand, the coolant flows from the side of the box around the lower box inner shell 103 and then flows out of the outlet 32; on the other hand, the coolant flows through the hollow position of the bottom box support beam 105 through the tail of the box, and then goes back to the outlet 32, which can ensure the uniformity and temperature uniformity of the flow channel.

[0108] In this embodiment, if Figure 8 and Fig. 9 As shown, the battery module 4 includes a cell group 401, a module CCS402 and a module cover 403. The module CCS402 is arranged on the upper side of the cell group 401, and the module CCS402 and the upper side of the cell group 401 are sealed; the module CCS402 is electrically connected to the BMS controller 7; the module cover 403 is arranged on the upper side of the module CCS402, and there is a sealing layer between the module cover 403 and the module CCS402; wherein, a sealing rubber ring 404 is arranged at the bottom of the module CCS402 and the top of each cell, and the sealing rubber ring 404 covers the top component of the cell.

[0109] Furthermore, the battery module 4 also includes an end plate 408, a strap 409 and an output electrode insulating seat 410. Its structural components are consistent with those of the ordinary battery module 4, and the difference is the sealing design between the module CCS402 and the battery cell:

[0110] 1. There is a sealing layer between the module cover 403 and the module CCS402, which ensures that the inside of the module CCS402 is isolated from the outside after sealing;

[0111] 2. There is a sealing layer between the module CCS402 and the battery cell.

[0112] like Fig. 9 As shown, a sealing rubber ring 404 is provided at the bottom of the module CCS402 and the top of each battery cell. The sealing rubber ring 404 and the integrated board of the module CCS402 are integrally formed by an online foaming process. The sealing rubber ring 404 covers the top key components such as the battery cell pole and the battery cell explosion-proof valve 5. After the module CCS402 is welded to the battery cell, a direct short circuit of a single battery cell can be avoided.

[0113] In this embodiment, the thickness T of the module upper cover 403 in the area of ​​the explosion-proof valve 5 at the top of the battery cell is less than 0.5 mm.

[0114] like Figure 8 and Fig. 9 As shown, the circled areas in the figure are the explosion-proof valve 5 areas on the top of the battery cell. In this embodiment, the module cover 403 is thinned in the explosion-proof valve 5 area, and the thickness T is less than 0.5mm. This can ensure that after the battery cell thermal runaway, the module cover 403 only opens a gap at the spray valve, which can accurately control the fire situation of the battery cell.

[0115] In this embodiment, when the battery cell has thermal runaway, the voltage and temperature signals of the battery cell will suddenly change, and the explosion-proof valve 5 of the battery cell will start to spray gas. At this time, the fire alarm 10 will also send out an alarm signal after detecting the combustible gas, and the signal will be transmitted to the BMS controller 7; the BMS controller 7 will first disconnect the relay of the power distribution unit 8 to ensure that the battery pack is in an open circuit state; if the temperature continues to rise and the fire is out of control, the BMS will send a signal to the electromagnetic puncture valve 9 to open the electromagnetic puncture valve 9, and the coolant can directly flow into the battery pack to extinguish the internal flame. In addition, the water inlet and outlet of the battery pack can also be increased with a control valve and a liquid level sensor in the battery pack, which can control the height of the liquid level inside the battery pack, the speed of the internal spraying water, and prevent the backflow of the battery pack coolant.

[0116] Fig.10 This is the control principle diagram of the immersion spray battery pack: starting from the thermal runaway of the first battery cell of the battery pack: when the first battery cell thermally runs away, the voltage and temperature signals of the battery cell will suddenly change. At this time, the fire alarm 10 will also send out an alarm signal after detecting the combustible gas. The signals are transmitted to the BMS controller 7. The BMS controller 7 will first disconnect the relay of the power distribution unit 8 to ensure that the battery pack is in an open circuit state. If a single battery cell is out of control and the temperature is controllable, the puncture valve does not need to be opened, and the hidden danger can be eliminated by only disconnecting the circuit and leaving it still.

[0117] If a single battery cell is out of control and the temperature is uncontrollable, the BMS will send a signal to the electromagnetic puncture valve 9 to open the electromagnetic puncture valve 9, and the coolant can directly flow into the battery pack to extinguish the internal flame. This process requires real-time monitoring of the liquid level in the battery pack and the temperature of the battery cell. If the battery pack is full of liquid, the liquid level alarm will send a signal, and the BMS will control the liquid inlet 31 and the liquid outlet 32 ​​to close, so as to prevent the coolant from flowing back and polluting the cooling system.

[0118] If multiple battery cells are out of control and the temperature is uncontrollable, the puncture valve needs to be opened and the liquid outlet 32 ​​needs to be closed at the same time. The coolant can flow directly into the battery pack to extinguish the internal flame. Closing the liquid outlet 32 ​​can increase the speed of coolant inflow into the battery pack, making it easier for the liquid to fill the battery pack as quickly as possible to stabilize the thermal runaway situation in the pack. If the battery pack is full of liquid, the liquid level alarm will send a signal, and the BMS will control the liquid inlet 31 and the liquid outlet 32 ​​to be closed to prevent the coolant from flowing back and polluting the cooling system.

[0119] Example 2

[0120] This embodiment provides a battery pack thermal runaway control method, which is used for the immersion spray type battery pack in Embodiment 1, and includes the following steps:

[0121] BMS determines the number of out-of-control cells:

[0122] If a single cell is out of control and the temperature is controllable, the control relay is disconnected and left to stand;

[0123] If a single battery cell is out of control and the temperature is uncontrollable, open the electromagnetic puncture valve 9 and monitor the coolant level and battery cell temperature in the battery pack;

[0124] If multiple cells are out of control and the temperature is controllable, open the electromagnetic puncture valve 9, monitor the liquid level in the package and the temperature of the cells;

[0125] If multiple cells are out of control and the temperature is uncontrollable, the electromagnetic puncture valve 9 is opened, the liquid outlet 32 ​​is closed, and the liquid level in the battery pack is monitored;

[0126] If the battery pack is full of liquid, the liquid level alarm sends a signal, and the BMS controls the liquid inlet 31 and the liquid outlet 32 ​​to be closed.

[0127] Specifically, the thermal runaway of the first battery cell in the battery pack is taken as the starting point: when the first battery cell is in thermal runaway, the voltage and temperature signals of the battery cell will suddenly change. At this time, the fire alarm 10 will also send out an alarm signal after detecting the combustible gas. The signals are transmitted to the BMS controller 7. The BMS controller 7 will first disconnect the relay of the power distribution unit 8 to ensure that the battery pack is in an open circuit state. If a single battery cell is out of control and the temperature is controllable, the puncture valve does not need to be opened, and the hidden danger can be eliminated by only disconnecting the circuit and leaving it still.

[0128] If a single battery cell is out of control and the temperature is uncontrollable, the BMS will send a signal to the electromagnetic puncture valve 9 to open the electromagnetic puncture valve 9, and the coolant can directly flow into the battery pack to extinguish the internal flame. This process requires real-time monitoring of the liquid level in the battery pack and the temperature of the battery cell. If the battery pack is full of liquid, the liquid level alarm will send a signal, and the BMS will control the liquid inlet 31 and the liquid outlet 32 ​​to close, so as to prevent the coolant from flowing back and polluting the cooling system.

[0129] If multiple battery cells are out of control and the temperature is uncontrollable, the puncture valve needs to be opened and the liquid outlet 32 ​​needs to be closed at the same time. The coolant can flow directly into the battery pack to extinguish the internal flame. Closing the liquid outlet 32 ​​can increase the speed of coolant inflow into the battery pack, making it easier for the liquid to fill the battery pack as quickly as possible to stabilize the thermal runaway situation in the pack. If the battery pack is full of liquid, the liquid level alarm will send a signal, and the BMS will control the liquid inlet 31 and the liquid outlet 32 ​​to be closed to prevent the coolant from flowing back and polluting the cooling system.

[0130] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. An immersion spray type battery pack, characterized in that: include: A lower box body (1) and an upper cover (2) arranged on the upper side of the lower box body (1), wherein the lower box body (1) is provided with a liquid inlet (31) and a liquid outlet (32) communicating with the interior of the lower box body (1); A battery module (4) is placed inside the lower box (1); Wherein, coolant is injected into the lower box body (1) through the liquid inlet (31) and discharged through the liquid outlet (32), and the coolant level inside the lower box body (1) is higher than the upper side of the battery module (4).

2. The immersion spray type battery pack according to claim 1, characterized in that: The lower box (1) comprises: A lower box shell (101) and a lower box bottom plate (102) fixed to the bottom of the lower box shell (101), wherein a placement cavity is formed between the lower box shell (101) and the lower box bottom plate (102); The lower box inner shell (103) is fixedly mounted inside the placement cavity, and the side edge of the lower box inner shell (103) is sealed and fixed to the side edge of the lower box outer shell (101), so as to form a cooling cavity between the cavity wall of the placement cavity and the outer wall of the lower box inner shell (103); the cooling cavity is in communication with the liquid inlet (31) and the liquid outlet (32); A flow channel partition plate (104) is fixed in the cooling cavity.

3. The immersion spray type battery pack according to claim 2, characterized in that: The height of the liquid outlet (32) is at least 3 mm greater than the height of the upper side of the battery module (4).

4. The immersion spray type battery pack according to claim 2, characterized in that: The lower box body (1) further comprises a box body support beam (105), wherein the box body support beam (105) is fixed inside the lower box body outer shell (101), and the box body support beam (105) adopts a hollow structure.

5. The immersion spray type battery pack according to claim 2, characterized in that: The side of the lower box inner shell (103) is bent outward and placed in the step groove on the side of the lower box outer shell (101); the step groove on the side of the lower box outer shell (101) is provided with a glue groove (405), and a glue overflow groove (406) and a bolt hole (407) arranged near the glue groove (405).

6. The immersion spray type battery pack according to any one of claims 1 to 5, characterized in that: The upper cover (2) is provided with an explosion-proof valve (5) communicating with the interior of the lower box (1), a high- and low-pressure connector (6), and a BMS controller (7) electrically connected to the high- and low-pressure connector (6).

7. The immersion spray type battery pack according to claim 6, characterized in that: The lower box (1) is also provided with: A power distribution unit (8) electrically connected between the battery module (4) and the high and low voltage connectors (6); an electromagnetic puncture valve (9), electrically connected to the BMS controller (7), the electromagnetic puncture valve (9) being fixed to the side wall of the battery module (4); the electromagnetic puncture valve (9) being configured to be opened under the control of the BMS controller (7) to allow coolant to enter the interior of the battery module (4); A fire alarm (10) is electrically connected to the BMS controller (7).

8. The immersion spray type battery pack according to claim 6, characterized in that: The battery module (4) comprises: Battery cell group (401); A module CCS (402) is arranged on the upper side of the battery cell group (401), and the module CCS (402) and the upper side of the battery cell group (401) are sealed; the module CCS (402) is electrically connected to the BMS controller (7); A module upper cover (403) is disposed on the upper side of the module CCS (402), and a sealing layer is present between the module upper cover (403) and the module CCS (402); The bottom of the module CCS (402) and the top of each battery cell are provided with a sealing rubber ring (404), and the sealing rubber ring (404) covers the top component of the battery cell.

9. The immersion spray type battery pack according to claim 8, characterized in that: The thickness T of the module upper cover (403) in the area of ​​the explosion-proof valve (5) at the top of the battery cell is less than 0.5 mm.

10. A method for controlling thermal runaway of a battery pack, characterized in that: The immersion spray type battery pack used in any one of claims 1 to 9 comprises the following steps: BMS determines the number of out-of-control cells: If a single cell is out of control and the temperature is controllable, the control relay is disconnected and left to stand; If a single battery cell is out of control and the temperature is uncontrollable, the electromagnetic puncture valve (9) is opened and the coolant level in the battery pack and the battery cell temperature are monitored; If multiple cells are out of control and the temperature is controllable, the electromagnetic puncture valve (9) is opened, and the liquid level in the package and the temperature of the cells are monitored; If multiple cells are out of control and the temperature is uncontrollable, the electromagnetic puncture valve (9) is opened, the liquid outlet (32) is closed, and the liquid level in the battery pack is monitored; If the battery pack is full of liquid, the liquid level alarm sends a signal, and the BMS controls the liquid inlet (31) and the liquid outlet (32) to be closed.

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