A battery pack

Abstract

This utility model discloses a battery pack, including a battery housing and individual battery cells disposed within the inner cavity of the battery housing. The battery housing is characterized by a pressure relief structure, and each battery cell is equipped with an explosion-proof valve. The explosion-proof valve is connected to the pressure relief structure via an exhaust chamber. A fire extinguishing element is disposed at the upstream end of the pressure relief structure, and the fire extinguishing element has multiple flame-arresting through holes. The cross-sectional area of ​​each flame-arresting through hole is s, and the length of the exhaust chamber is L. The ratio of s / L is in the range of 0.000079 mm ≤ s / L ≤ 0.16 mm. This utility model's battery pack, while ensuring the flame-arresting effect of the pressure relief mechanism, also guarantees a good pressure relief effect, improving the safety performance of the battery pack in the event of thermal runaway.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery pack. Background Technology

[0002] The power battery pack is the energy storage and supply device for new energy vehicles. The battery pack includes a battery box and multiple battery cells set in the box. The battery cells are lithium batteries. During use, especially under overcharging, over-discharging, compression and puncture, thermal runaway is likely to occur. Thermal runaway of battery cells is accompanied by the release of a large amount of gas and heat. The gases released when battery cells thermally runaway include various flammable gases and oxygen. Therefore, the battery pack is prone to fire when it thermally runs away, posing a great safety risk. Utility Model Content

[0003] In view of this, the present invention provides a battery pack that ensures both the flame-retardant effect of the pressure relief mechanism and a good pressure relief effect, thereby improving the safety performance of the battery pack in the event of thermal runaway.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A battery pack includes a battery housing and individual battery cells disposed within the inner cavity of the battery housing. The battery housing is provided with a pressure relief structure, and each individual battery cell is provided with an explosion-proof valve. The explosion-proof valve is connected to the pressure relief structure through an exhaust chamber. A fire extinguishing device is provided at the upstream end of the pressure relief structure. The fire extinguishing device is provided with multiple fire-resistant through holes. The cross-sectional area of ​​the fire-resistant through holes is s, and the length of the exhaust chamber is L. The range of s / L is 0.000079mm≤s / L≤0.16mm.

[0006] As can be seen from the above technical solution, the battery pack provided by this utility model, by setting a fire-extinguishing component 3 with multiple fire-arresting through holes, prevents the flames from being ejected from the high-temperature gas flow, thereby preventing the flames from being ejected when the battery experiences thermal runaway, and reducing the safety risks caused by open flames. By limiting the ratio of the cross-sectional area of ​​the fire-arresting through holes to the length of the exhaust chamber, the fire-arresting effect of the pressure relief mechanism is ensured while maintaining a good pressure relief effect, thus improving the safety performance of the battery pack under thermal runaway conditions. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 A schematic diagram of the battery pack from one angle provided in an embodiment of this utility model;

[0009] Figure 2 This is a structural schematic diagram of the battery pack provided in an embodiment of the present invention from another angle;

[0010] Figure 3 A cross-sectional view of the AA position of a battery pack according to an embodiment of the present invention;

[0011] Figure 4 A schematic diagram of the cross-sectional structure of the fire extinguishing component provided in this embodiment of the utility model;

[0012] Figure 5 A cross-sectional view of the AA position of the battery pack provided in another embodiment of the present invention;

[0013] Figure 6 A schematic diagram of the arrangement structure of the first airflow baffle provided in an embodiment of the present utility model;

[0014] Figure 7 A schematic diagram of the arrangement structure of the first airflow baffle provided in another embodiment of the present utility model;

[0015] Figure 8 A cross-sectional view of the AA position of the battery pack provided in another embodiment of the present invention;

[0016] Figure 9 This is a schematic diagram of the structure of a fire extinguishing device provided in an embodiment of the present invention.

[0017] in:

[0018] 1. Battery housing,

[0019] 101. Side panel of the container; 102. Cover of the container; 103. Bottom panel.

[0020] 2. Pressure relief structure,

[0021] 3. Fire extinguishing equipment,

[0022] 301, Flame-arresting through hole; 3011, First flame-arresting branch through hole; 3012, Second flame-arresting branch through hole.

[0023] 4. Exhaust chamber,

[0024] 401. Exhaust bottom surface; 402. Exhaust top surface.

[0025] 5. Battery cells,

[0026] 6. Explosion-proof valve,

[0027] 7. First airflow baffle,

[0028] 8. Second airflow baffle. Detailed Implementation

[0029] This utility model discloses a battery pack that ensures both the flame-retardant effect of the pressure relief mechanism and a good pressure relief effect, thereby improving the safety performance of the battery pack in the event of thermal runaway.

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] See Figures 1 to 5 The battery pack of this utility model includes a battery housing 1 and battery cells 5 disposed within the cavity of the battery housing 1. A pressure relief structure 2 is provided on the battery housing 1, and an explosion-proof valve 6 is provided on the battery cells 5. The explosion-proof valve 6 is connected to the pressure relief structure 2 through an exhaust chamber 4. A fire extinguishing element 3 is provided at the upstream end of the pressure relief structure 2. The fire extinguishing element 3 is provided with multiple fire-resistant through holes 301, the cross-sectional area of ​​which is s. Figure 4 As shown, the length of the exhaust chamber 4 is L, as... Figure 3 and Figure 5 As shown, the range of s / L is 0.000079mm ≤ s / L ≤ 0.16mm. The upstream end of the pressure relief structure 2 is defined by the flow direction of the airflow; the upstream is the position where the airflow arrives first. Specifically, the value of s / L can be any value among 0.000079mm, 0.001mm, 0.1mm, and 0.16mm, or a value between any two of these values.

[0032] The battery housing 1 includes a base plate 103, side plates 101, and a cover plate 102. The base plate 103 and side plates 101 form a chamber with a sealed bottom and an open top for placing individual battery cells 5. The top opening of the chamber is connected to the cover plate 102. A pressure relief hole communicating with an exhaust chamber 4 is provided on the side plate 101, and a pressure relief structure 2 is installed at the pressure relief hole. A fire extinguishing element 3 is provided on the side of the pressure relief structure 2 closest to the exhaust chamber 4. Since the fire-arresting through-hole 301 on the fire extinguishing element 3 is used for fire suppression, the size of the fire-arresting through-hole 301 is not greater than the MESG value to achieve its fire-arresting purpose. The cross-sectional area s of the fire-arresting through-hole 301 is calculated based on the size of the through-hole. The MESG value, or Maximum Test Safe Gap Value, is an important parameter used to evaluate the explosion-proof performance of electrical equipment in an environment containing flammable gases. It is the channel size that, under specific conditions (typically 0.1 MPa pressure and 20°C temperature), just enough to extinguish the flame. When battery cell 5 experiences thermal runaway, a mixture of various gases is generated. The MESG value can be taken as the value of the gas component with the lowest MESG value in the mixture, serving as the basis for the orifice size of the flame arrestor through-hole 301; the MESG value can also be obtained using the following formula: Where Xi is the volume fraction of the component, MESGi is the MESG value of each component, and the final MESG value of the mixed gas is calculated, i.e., MESG. mix According to the calculated MESG mix 3. Matching fire extinguishing components with corresponding hole sizes.

[0033] By setting a flame-arresting through-hole 301 on the fire extinguishing component 3, the cross-sectional area s of the flame-arresting through-hole 301 is limited to ensure the flame-arresting effect. The larger the value of s, i.e., the larger the hole, the better the pressure relief effect; the smaller the value of s, i.e., the smaller the hole, the better the fire extinguishing effect. The longer the length L of the exhaust chamber 4, the lower the temperature of the airflow will be, thus aiding in the fire extinguishing effect. If the length L of the exhaust chamber 4 is too long, the pressure relief effect will be affected due to the excessively long airflow path. If the value of s / L is too small, the diameter of the flame-arresting through-hole 301 on the fire extinguishing component 3 will be small, and the length L of the exhaust chamber 4 will be too long, affecting the gas flow to the pressure relief structure 2, preventing the pressure relief structure 2 from relieving pressure in time. If the value of s / L is too large, the diameter of the flame-arresting through-hole 301 on the fire extinguishing component 3 will be large, and the length L of the exhaust chamber 4 will be too short, resulting in a poor fire extinguishing effect. The length L of the exhaust chamber 4 is the distance from the fire extinguishing component 3 to the weakest part of the explosion-proof valve 6 on the nearest battery cell 5 to the fire extinguishing component 3. Specifically, the exhaust chamber 4 is located at the bottom plate 103.

[0034] The battery pack of this invention incorporates a fire-extinguishing component 3 with multiple fire-arresting through-holes 301 to prevent the ejection of flames from the high-temperature gas flow. This prevents the ejection of flames from the combustion of flammable gases during battery thermal runaway, reducing the safety risks posed by open flames. By limiting the ratio of the cross-sectional area of ​​the fire-arresting through-holes 301 to the length L of the exhaust chamber 4, the fire-arresting effect of the pressure relief mechanism is ensured while maintaining good pressure relief, thus improving the safety performance of the battery pack in the event of thermal runaway.

[0035] To increase the airflow path and reduce the risk of open flame ejection, refer to Figure 5 As shown, the exhaust chamber 4 is equipped with staggered first airflow baffles 7 and second airflow baffles 8. The first airflow baffles 7 are disposed on the first surface of the exhaust chamber 4, and the second airflow baffles 8 are disposed on the second surface of the exhaust chamber 4, with the first surface and the second surface facing each other. Multiple first airflow baffles 7 and second airflow baffles 8 are provided. By setting the staggered first airflow baffles 7 and second airflow baffles 8, the airflow path is changed from a straight path to an S-shaped path, extending the airflow path without increasing the space of the exhaust chamber 4, thus improving the fire extinguishing effect.

[0036] Furthermore, the exhaust chamber 4 includes an exhaust bottom surface 401 and an exhaust top surface 402. A first airflow baffle 7 is disposed on the exhaust bottom surface 401, and a second airflow baffle 8 is disposed on the exhaust top surface 402. Both the first airflow baffle 7 and the second airflow baffle 8 extend along the width W direction of the exhaust chamber 4, as shown in the figure. Figure 2 As shown. It is understandable that the first airflow baffle 7 can be spaced apart along the width direction of the exhaust chamber 4, such as... Figure 6 As shown, it can also be continuously arranged along the width direction of the exhaust chamber 4, such as... Figure 7 As shown. Similarly, the second airflow baffle 8 is configured similarly to the first airflow baffle 7, except that the second airflow baffle 8 must avoid the location of the explosion-proof valve 6 to prevent affecting the airflow discharge when the explosion-proof valve 6 opens. Along the length of the exhaust chamber 4, the first airflow baffle 7 and the second airflow baffle 8 are spaced at a predetermined distance, which is set according to actual needs. The length direction of the exhaust chamber 4 is perpendicular to its width direction.

[0037] In one embodiment, the exhaust bottom surface 401 and the exhaust top surface 402 are arranged in parallel. The distance between the top of the first airflow baffle 7 and the exhaust bottom surface 401 is not less than half the distance between the exhaust bottom surface 401 and the exhaust top surface 402. The distance between the top of the second airflow baffle 8 and the exhaust top surface 402 is not less than half the distance between the exhaust bottom surface 401 and the exhaust top surface 402, so that more airflow flows along the S-shaped path and the fire extinguishing effect is better.

[0038] For ease of processing, the first airflow baffle 7 is positioned perpendicular to the exhaust bottom surface 401, and the second airflow baffle 8 is positioned perpendicular to the exhaust top surface 402. Figure 5 As shown, this facilitates the connection between the airflow baffle and the corresponding plate surface. The connection can be made by welding or by connecting parts.

[0039] To improve the pressure relief effect, the first airflow baffle 7 is inclinedly disposed on the bottom surface 401 of the exhaust, and the second airflow baffle 8 is inclinedly disposed on the top surface 402 of the exhaust. The inclination direction of both the first airflow baffle 7 and the second airflow baffle 8 is towards the direction of gas flow. Figure 8 As shown, the tilt angles of the first airflow baffle 7 and the second airflow baffle 8 may be the same or different.

[0040] To further improve the pressure relief effect, the first airflow baffle 7 is provided with an airflow hole. Alternatively, the second airflow baffle 8 is provided with an airflow hole. Alternatively, both the first airflow baffle 7 and the second airflow baffle 8 are provided with airflow holes.

[0041] In one embodiment, to further reduce the temperature of the thermally runaway gas flow and enhance the fire extinguishing effect, a liquid cooling structure is provided in the exhaust chamber 4. This liquid cooling structure can be a liquid cooling pipe, a liquid cooling plate, or other commonly used cooling structures; no limitation is made here. To facilitate installation or positioning, the liquid cooling structure is disposed on the exhaust bottom surface 401 or the exhaust top surface 402. To improve the cooling efficiency of the gas, the liquid cooling structure can also be disposed on both the exhaust bottom surface 401 and the exhaust top surface 402.

[0042] The height of the exhaust chamber 4 ranges from 10mm to 40mm, and is the distance between the bottom exhaust surface 401 and the top exhaust surface 402. Specifically, the height of the exhaust chamber 4 can be any value among 10mm, 20mm, 30mm, and 40mm, or a value between any two of these. A larger height of the exhaust chamber 4 results in better pressure relief for the battery pack; however, the height of the exhaust chamber 4 cannot be too large, otherwise it will affect the space of other components or structures within the battery pack, reducing the space utilization rate of the battery.

[0043] To ensure both fire extinguishing and pressure relief effects, the fire extinguishing component 3 includes a first fire-resistant zone and a second fire-resistant zone. The first fire-resistant zone has a first fire-resistant branch hole 3011, and the second fire-resistant zone has a second fire-resistant branch hole 3012. The first fire-resistant zone is positioned close to the explosion-proof valve 6, and the second fire-resistant zone is positioned away from the explosion-proof valve 6. Specifically, when installed at the pressure relief hole on the side plate 101 of the enclosure, the first fire-resistant zone is located at the lower end, and the second fire-resistant zone is located at the upper end. The cross-sectional area of ​​the first fire-resistant branch hole is s1, and the cross-sectional area of ​​the second fire-resistant branch hole is s2, where s1 < s2. Figure 9 As shown. During thermal runaway, the flow path of the high-temperature gas flow from the first flame arrestor zone is relatively short. Therefore, the size of the first flame arrestor orifice 3011 is smaller to improve the wall effect and enhance the flame arresting effect. The flow path of the high-temperature gas flow from the second flame arrestor zone is relatively long. Therefore, the size of the second flame arrestor orifice 3012 is larger to meet the flame arresting requirements and improve the pressure relief effect.

[0044] In one embodiment, both the first flame-arresting through-hole 3011 and the second flame-arresting through-hole 3012 are circular through-holes. The diameter of the first flame-arresting through-hole 3011 is smaller than the diameter of the second flame-arresting through-hole 3012, that is, the cross-sectional area of ​​the first flame-arresting through-hole 3011 is smaller than the cross-sectional area of ​​the second flame-arresting through-hole 3012. In other embodiments, the first flame-arresting through-hole 3011 and the second flame-arresting through-hole 3012 may also be elliptical through-holes or polygonal through-holes, which is not limited here.

[0045] Specifically, the cross-sectional area s of the flame-retardant through-hole 301 is in the range of 0.19 mm. 2 ≤s≤3.2mm 2 Specifically, s can be 0.19mm 2 0.5mm 2 1.5mm 2 1.5mm 2 3.2mm 2The length L of the exhaust chamber 4 is in the range of 20mm ≤ L ≤ 2400mm. Specifically, L can be any value of 20mm, 200mm, 500mm, 1000mm, or 2400mm, or any value between any two. When the battery cell 5 experiences thermal runaway, the high-temperature gas inside flows into the exhaust chamber 4 through the explosion-proof valve 6. The airflow in the exhaust chamber 4 flows through the flame arrestor hole 301 to the pressure relief structure 2, where the high-temperature gas flows out to release pressure. The flame arrestor hole 301 is a small channel, and its wall effect prevents flame propagation. Free radicals in the airflow frequently collide and absorb with the wall of the flame arrestor hole 301, resulting in a decrease in the number of free radicals and a reduction in their kinetic energy, thus preventing the combustion reaction of the high-temperature gas from continuing. The smaller the size of the flame arrestor hole 301, the more dominant the collision between free radicals and the wall, and the more significant the flame extinguishing effect. To ensure effective fire suppression and facilitate pressure relief, the surface area of ​​the fire extinguishing element 3 is divided into the aforementioned first fire-suppressing zone and second fire-suppressing zone. In one embodiment, as... Figure 9 As shown, the boundary line between the first and second fire-resistant zones is set along the diameter of the fire extinguishing element 3, meaning that the first and second fire-resistant zones each occupy half of the area. In other embodiments, the ratio of the occupied areas of the two zones can be adjusted according to actual conditions.

[0046] To extend the service life of the fire extinguishing element 3, it is made of metal mesh. The use of metal increases the strength of the fire extinguishing element 3 and prevents it from melting when subjected to high-temperature airflow, thus significantly improving its service life.

[0047] To improve fire extinguishing effectiveness, the fire extinguishing element 3 can be multi-layered. The size of the flame-arresting through-holes 301 on different layers of the fire extinguishing element 3 may be the same or different. When the size of the flame-arresting through-holes 301 on different layers of the fire extinguishing element 3 is different, the fire extinguishing elements 3 on different layers are arranged in descending order of the size of the flame-arresting through-holes 301. The fire extinguishing element 3 with the largest flame-arresting through-hole 301 is placed away from the pressure relief structure 2, and the fire extinguishing element 3 with the smallest flame-arresting through-hole 301 is placed closer to the pressure relief structure 2. That is, the size of the flame-arresting through-holes 301 on different layers of the fire extinguishing element 3 decreases sequentially along the airflow direction.

[0048] This utility model's battery pack, by limiting the ratio of the cross-sectional area *s* of the flame-arresting through-hole 301 to the length *L* of the exhaust chamber 4, ensures both the flame-arresting effect of the pressure relief mechanism and a good pressure relief effect, thereby improving the safety performance of the battery pack in the event of thermal runaway. The unidirectional arrows in the above figures indicate the airflow direction. Figure 2 The double-headed arrows in the diagram indicate the direction of extension of the width W of the exhaust chamber 4.

[0049] In the description of this solution, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this solution, "multiple" means two or more, unless otherwise explicitly specified.

[0050] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0051] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A battery pack, comprising a battery housing and individual battery cells disposed within the cavity of the battery housing, characterized in that, The battery box is equipped with a pressure relief structure, and each battery cell is equipped with an explosion-proof valve. The explosion-proof valve is connected to the pressure relief structure through an exhaust chamber. A fire extinguishing device is provided at the upstream end of the pressure relief structure. The fire extinguishing device is equipped with multiple fire-resistant through holes. The cross-sectional area of ​​the fire-resistant through holes is s, and the length of the exhaust chamber is L. The range of s / L is 0.000079mm≤s / L≤0.16mm.

2. The battery pack according to claim 1, characterized in that, The exhaust chamber is provided with a first airflow baffle and a second airflow baffle arranged in an alternating manner. The first airflow baffle is disposed on the first surface of the exhaust chamber, and the second airflow baffle is disposed on the second surface of the exhaust chamber. The first surface and the second surface are disposed opposite to each other. Multiple first and second airflow baffles are provided.

3. The battery pack according to claim 2, characterized in that, The exhaust chamber includes an exhaust bottom surface and an exhaust top surface. A first airflow baffle is disposed on the exhaust bottom surface, and a second airflow baffle is disposed on the exhaust top surface. Both the first airflow baffle and the second airflow baffle extend along the width direction of the exhaust chamber. Along the length of the exhaust chamber, the first airflow baffle and the second airflow baffle are set at a predetermined distance.

4. The battery pack according to claim 3, characterized in that, The exhaust bottom surface and exhaust top surface are arranged in parallel. The distance between the top of the first airflow baffle and the exhaust bottom surface is not less than half the distance between the exhaust bottom surface and the exhaust top surface. The distance between the top of the second airflow baffle and the exhaust top surface is not less than half the distance between the exhaust bottom surface and the exhaust top surface.

5. The battery pack according to claim 3 or 4, characterized in that, The first airflow baffle is arranged perpendicular to the bottom surface of the exhaust gas, and the second airflow baffle is arranged perpendicular to the top surface of the exhaust gas.

6. The battery pack according to claim 3 or 4, characterized in that, The first airflow baffle is inclinedly disposed on the bottom surface of the exhaust, and the second airflow baffle is inclinedly disposed on the top surface of the exhaust. The inclination direction of the first airflow baffle and the second airflow baffle are both towards the direction of gas flow.

7. The battery pack according to claim 2, characterized in that, Airflow holes are provided on the first airflow baffle and / or the second airflow baffle.

8. The battery pack according to claim 1, characterized in that, The exhaust chamber is equipped with a liquid cooling structure; The liquid cooling structure is disposed on the bottom surface of the exhaust and / or the top surface of the exhaust.

9. The battery pack according to claim 1, characterized in that, The height of the exhaust chamber ranges from 10mm to 40mm.

10. The battery pack according to claim 1, characterized in that, The fire extinguishing device includes a first fire-blocking zone and a second fire-blocking zone. The first fire-blocking zone is provided with a first fire-blocking branch hole, and the second fire-blocking zone is provided with a second fire-blocking branch hole. The first fire-blocking zone is located close to the explosion-proof valve, and the second fire-blocking zone is located away from the explosion-proof valve. The cross-sectional area of ​​the first fire-blocking branch hole is s1, and the cross-sectional area of ​​the second fire-blocking branch hole is s2, where s1 < s2.

11. The battery pack according to claim 1, characterized in that, The cross-sectional area s of the flame-retardant through-hole is in the range of 0.19 mm. 2 ≤s≤3.2mm 2 The length L of the exhaust chamber is in the range of 20mm≤L≤2400mm.

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