Battery pack pressure relief mechanism

Abstract

The utility model discloses a kind of battery pack pressure relief mechanism, including pressure relief valve and fire extinguishing part, the pressure relief valve is installed in the pressure relief hole position on the box body lateral wall of battery pack, the pressure relief hole is communicated with the pressure relief cavity of battery pack, the fire extinguishing part is arranged between the pressure relief valve and the pressure relief cavity, and the fire extinguishing part is set corresponding the pressure relief hole, characterized by, multiple fire resistance through holes for fire resistance are arranged on the fire extinguishing part, the cross-sectional area of the fire resistance through hole is s, the porosity on the fire extinguishing part is a, the range of a×s is 0.04mm 2 ≤a×s≤2.5mm 2 The utility model discloses a kind of battery pack pressure relief mechanism, in guarantee the fire resistance effect of pressure relief mechanism, while guaranteeing that fire extinguishing part has good pressure relief effect, reduce the risk of battery pack from bottom plate position blasting, and safety performance is better.

Description

Technical Field

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

[0002] The power battery pack is an energy storage and supply device for new energy vehicles. The battery pack includes a battery box and multiple battery cells set inside the box. The battery cells are lithium batteries. During use, especially during overcharging, over-discharging, compression and puncture, thermal runaway is likely to occur. Battery thermal runaway is accompanied by the release of a large amount of gas and heat. In order to prevent the closed battery box from being subjected to too much pressure and exploding, a pressure relief valve needs to be installed on the battery box to actively relieve pressure.

[0003] When a battery experiences thermal runaway, it releases various gases at very high temperatures. Some of these gases are flammable and can easily ignite when ejected from the pressure relief valve at these high temperatures, posing a safety hazard. Therefore, a fire extinguishing net needs to be installed at the air inlet of the pressure relief valve. However, the obstruction caused by the fire extinguishing net can affect the airflow discharge speed within the battery pack, preventing the pressure relief valve from releasing pressure in time. This can lead to a violent explosion of high-pressure gas from the base plate, posing a significant safety risk. Utility Model Content

[0004] In view of this, the present invention provides a battery pack pressure relief mechanism that, while ensuring the fire-resistant effect of the pressure relief mechanism, also ensures that the fire extinguishing component has a good pressure relief effect, reducing the risk of the battery pack exploding from the bottom plate and improving safety performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A battery pack pressure relief mechanism includes a pressure relief valve and a fire extinguishing component. The pressure relief valve is installed at a pressure relief hole on the side wall of the battery pack housing, and the pressure relief hole communicates with the pressure relief chamber of the battery pack. The fire extinguishing component is disposed between the pressure relief valve and the pressure relief chamber, and is positioned corresponding to the pressure relief hole. The fire extinguishing component has multiple fire-arresting through holes for flame arrest, the cross-sectional area of ​​which is s, and the porosity of the fire extinguishing component is a, where a × s is in the range of 0.04 mm. 2 ≤a×s≤2.5mm 2 .

[0007] As can be seen from the above technical solution, the battery pack pressure relief mechanism provided by this utility model, by setting a fire-extinguishing element between the pressure relief valve and the pressure relief chamber, and by setting multiple fire-extinguishing through holes on the fire-extinguishing element, prevents the flames of high-temperature gas combustion from being ejected, thereby preventing the flames of flammable gas combustion from being ejected from the pressure relief valve when the battery is thermally runaway, avoiding the flames from being ejected from the battery pack and igniting other components, and reducing the safety risks caused by open flames. By limiting the product of the cross-sectional area of ​​the fire-extinguishing through holes and the porosity of the fire-extinguishing element, the fire-extinguishing element is ensured to have a good pressure relief effect while ensuring the fire-extinguishing effect of the pressure relief mechanism, reducing the risk of the battery pack exploding from the bottom plate, and improving safety performance. Attached Figure Description

[0008] 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.

[0009] Figure 1 A schematic diagram of the battery pack from one angle provided in an embodiment of this utility model;

[0010] Figure 2 This is a structural schematic diagram of the battery pack provided in an embodiment of the present invention from another angle;

[0011] Figure 3 A cross-sectional view of the AA position of a battery pack according to an embodiment of the present invention;

[0012] Figure 4 A cross-sectional view of the AA position of the battery pack provided in another embodiment of the present invention;

[0013] Figure 5 for Figure 4 A partially enlarged structural diagram of part B in the diagram;

[0014] Figure 6 A schematic diagram of the structure of a fire extinguishing component installed on a battery box according to an embodiment of the present invention;

[0015] Figure 7 A schematic diagram of a fire extinguishing component installed on a battery box, according to another embodiment of the present invention;

[0016] Figure 8 for Figure 7 A structural diagram of the fire extinguishing device in the diagram;

[0017] Figure 9A schematic diagram of the structure of the fire extinguishing device provided in this embodiment of the present invention, showing the orthographic projection of the pressure relief hole on the side wall of the housing where the pressure relief hole is located, covering the portion of the pressure relief hole;

[0018] Figure 10 A schematic diagram showing the structure of the fire extinguishing device provided in this embodiment of the invention, with its orthographic projection on the side wall of the housing where the pressure relief hole is located covering the entire pressure relief hole;

[0019] Figure 11 A schematic diagram showing the structure in which the center line of the flame-arresting through hole is parallel to the axis of the pressure relief hole in an embodiment of this utility model;

[0020] Figure 12 This is a schematic diagram showing the structure of the flame-retardant through-hole provided in this embodiment of the invention, in which the center line of the hole is not parallel to the axis of the pressure relief hole.

[0021] in:

[0022] 1. Battery housing,

[0023] 101. Side panel of the container; 102. Cover of the container; 103. Bottom panel.

[0024] 2. Pressure relief valve

[0025] 3. Fire extinguishing equipment,

[0026] 301. Flame-retardant through hole

[0027] 4. Pressure relief chamber

[0028] 5. Battery cells,

[0029] 6. Pressure relief hole. Detailed Implementation

[0030] This utility model discloses a battery pack pressure relief mechanism, which ensures the fire-resistant effect of the pressure relief mechanism while ensuring that the fire extinguishing component has a good pressure relief effect, reducing the risk of the battery pack exploding from the bottom plate and improving safety performance.

[0031] 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.

[0032] See Figures 1 to 6The battery pack pressure relief mechanism of this utility model includes a pressure relief valve 2 and a fire extinguishing component 3. The pressure relief valve 2 is installed at the pressure relief hole 6 on the side wall 101 of the battery pack housing. The pressure relief hole 6 communicates with the pressure relief chamber 4 of the battery pack. The fire extinguishing component 3 is arranged between the pressure relief valve 2 and the pressure relief chamber 4, that is, the fire extinguishing component 3 is arranged at the front end of the pressure relief hole 6. Here, the front end of the pressure relief hole 6 refers to the upstream end of the gas flow, and the fire extinguishing component 3 is arranged corresponding to the pressure relief hole 6. The fire extinguishing component 3 is provided with multiple fire-arresting through holes 301 for flame arresting. The cross-sectional area of ​​the fire-arresting through holes 301 is s, and the porosity of the fire extinguishing component 3 is a, where a×s ranges from 0.04mm. 2 ≤a×s≤2.5mm 2 Specifically, the value of a×s can be 0.04 mm. 2 0.1mm 2 0.5mm 2 1mm 2 2mm 2 2.5mm 2 It can be any value in the range or a value between any two values.

[0033] The cross-sectional area 's' of the flame-arresting through-hole 301 is the area enclosed by the cross-sectional outline of the flame-arresting through-hole 301, taken from a surface perpendicular to its centerline. When the flame-arresting through-hole 301 is a constant-diameter through-hole, it is the area enclosed by the edge of the end hole of the flame-arresting through-hole 301. The battery pack includes a battery housing 1, which includes a bottom plate 103, side plates 101, and a cover plate 102. The bottom plate 103 and the side plates 101 form a chamber with a bottom seal and a top opening for placing individual battery cells 5. The top opening of the chamber is connected to the cover plate 102. A pressure relief hole 6 is provided on the side plate 101, and a pressure relief valve 2 is installed at the pressure relief hole 6. A fire extinguishing element 3 is provided on the side of the pressure relief valve 2 near the inner cavity of the battery housing 1. Since the flame-arresting through-hole 301 on the fire extinguishing component 3 is used for flame arrest, in order to achieve the flame-arresting purpose of the flame-arresting through-hole 301, the hole size of the flame-arresting through-hole 301 shall not exceed the MESG value. 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 just allows the flame to be extinguished under specific conditions (usually 0.1 MPa pressure and 20°C temperature). When the battery cell 5 experiences thermal runaway, a mixture of various gases will be generated. The MESG value can be taken as the value of the gas component with the lowest MESG value in the mixture, as the basis for the hole size of the flame-arresting 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 Refer to the calculated MESG mixA fire extinguishing component 3 with a corresponding orifice size is provided on the base plate 103. The pressure relief chamber 4 is connected to the explosion-proof valve of the battery cell 5. When the battery cell 5 experiences thermal runaway, the high-temperature gas inside flows into the pressure relief chamber 4 through the explosion-proof valve. The airflow in the pressure relief chamber 4 flows through the flame-arresting through-hole 301 to the pressure relief valve 2, and the high-temperature gas flows out through the pressure relief valve 2 to release pressure. The flame-arresting through-hole 301 is a small channel, and the wall effect of the flame-arresting through-hole 301 prevents the flame from spreading. Free radicals in the airflow frequently collide and absorb with the orifice wall of the flame-arresting through-hole 301, resulting in a reduction in the number of free radicals and their kinetic energy, thereby preventing the combustion reaction of the high-temperature gas from continuing. The smaller the orifice size of the flame-arresting through-hole 301, the more dominant the collision between free radicals and the orifice wall, and the more significant the flame extinguishing effect. In order to ensure the flame-arresting effect and facilitate pressure relief, multiple flame-arresting through-holes 301 are evenly distributed on the fire extinguishing component 3. Figures 3 to 5 The arrows in the diagram indicate the direction of airflow.

[0034] To ensure good fire-arresting and pressure-relief effects, the product range of the cross-sectional area *s* of the fire-arresting through-hole 301 and the porosity *a* of the fire extinguishing element 3 is limited. Porosity *a* is the ratio of the area of ​​all fire-arresting through-holes 301 on the fire extinguishing element 3 to the area of ​​the corresponding surface of the fire extinguishing element 3. The corresponding surface refers to the surface of the fire extinguishing element 3 where the fire-arresting through-holes 301 are located. A larger porosity *a* results in more fire-arresting through-holes 301 on the fire extinguishing element 3, leading to better exhaust and pressure relief. However, an excessively large porosity *a* can affect the strength of the fire extinguishing element 3, making it prone to thermal deformation and impacting the fire extinguishing effect. The cross-sectional area *s* of the fire-arresting through-hole 301 is the cross-sectional area of ​​a single fire-arresting through-hole 301. If the cross-sectional area *s* is too small, the pressure relief effect is poor; if it is too large, the fire extinguishing effect is poor. By limiting the range of a×s, the fire-resistant effect and pressure relief effect of the fire extinguishing component 3 can both meet the usage requirements. If the product of the cross-sectional area of ​​the fire-resistant through hole 301 and the porosity on the fire extinguishing component 3, a×s, is too small, the pressure relief effect will be poor; if the value is too large, the fire extinguishing effect will be poor.

[0035] The battery pack pressure relief mechanism of this invention uses a fire-extinguishing element 3 between the pressure relief valve 2 and the pressure relief chamber 4 to prevent flames from being ejected from the high-temperature gas flow. This prevents flames from igniting other components when the battery experiences thermal runaway, thus reducing the safety risk caused by open flames. By limiting the product of the cross-sectional area of ​​the fire-extinguishing holes 301 and the porosity of the fire-extinguishing element 3, the fire-extinguishing element 3 maintains both its fire-extinguishing effect and pressure relief performance, reducing the risk of the battery pack exploding from the base plate 103 and improving overall safety.

[0036] Specifically, the cross-sectional area s of the flame-retardant through-hole 301 is in the range of 0.19 mm² ≤ s ≤ 3.2 mm², where the value of s can be 0.19 mm². 2 1mm 2 2mm 2 3.2mm 2 The porosity 'a' on the fire extinguishing element 3 can be any value in the range of 0.2 ≤ a ≤ 0.95. Specifically, the value of 'a' can be any value among 0.2, 0.5, 0.7, and 0.95, or any value between any two. By limiting the cross-sectional area 's' of the fire-arresting through-hole 301, the fire-arresting effect of the fire-arresting through-hole 301 is ensured. By limiting the porosity 'a' on the fire extinguishing element 3, the pressure relief effect is ensured.

[0037] When the cross-sectional area *s* of the flame-arresting through-hole 301 is the same, different shapes of the flame-arresting through-hole 301 have different effects on the fire extinguishing and pressure relief effects. Taking circular and square flame-arresting through-holes 301 as examples, under the same cross-sectional area, the diameter of the circular hole is smaller than the diagonal line connecting the two sides of the square hole, that is, the maximum size of the circular hole is smaller than the maximum size of the square hole. A larger maximum size results in a poorer fire extinguishing effect but a better pressure relief effect. In one embodiment, the flame-arresting through-hole 301 is a circular hole. Circular holes have a good fire extinguishing effect but a poorer pressure relief effect. In this case, the range of *a*×s is 0.08 mm. 2 ≤a×s≤2.5mm 2 This is to ensure effective pressure relief. Specifically, the value of a×s can be 0.08 mm. 2 0.5mm 2 1mm 2 1.5mm 2 2.5mm 2 The value in the range is either any one of the two values ​​or a value between any two values. In another embodiment, the fire-arresting through-hole 301 is a square hole. Compared with a circular hole, a square hole has a better pressure relief effect but a worse fire extinguishing effect. In this case, the range of a×s is 0.04mm. 2 ≤a×s≤2.0mm 2 This is to ensure effective fire extinguishing. Specifically, the value of a×s can be 0.04mm. 2 0.5mm 2 1mm 2 2mm 2 The value can be any one of the given values ​​or a value between any two values. In other embodiments, the flame-retardant through-hole 301 can also be a triangular hole, a pentagonal hole, or other commonly used hole types, which are not limited here.

[0038] In one embodiment, reference is made to Figure 3 and Figure 7As shown, the orthographic projection of the fire extinguishing component 3 on the side wall 101 of the housing where the pressure relief hole 6 is located coincides with the pressure relief hole 6. Here, the orthographic projection of the fire extinguishing component 3 on the side wall 101 of the housing where the pressure relief hole 6 is located refers to the projection of the fire extinguishing component 3 excluding the installation edge. Since the pressure relief hole 6 is a circular hole, in this embodiment, the fire extinguishing component 3 is a circular plate, as shown... Figure 8 As shown in the figure. In this embodiment, the fire extinguishing component 3 has a good fire extinguishing effect and can also save on the cost of the fire extinguishing component 3.

[0039] In another embodiment, the pressure relief hole 6 is at least partially covered by the orthographic projection of the fire extinguishing element 3 onto the side wall 101 of the housing where the pressure relief hole 6 is located, to reduce the impact on the pressure relief effect. To ensure the pressure relief effect, the surface area of ​​the fire-resistant through-hole 301 of the fire extinguishing element 3 is larger than the cross-sectional area of ​​the pressure relief hole 6. (Refer to...) Figure 9 As shown, the orthographic projection of the fire extinguishing component 3 on the side wall 101 of the housing where the pressure relief hole 6 is located partially covers the pressure relief hole 6; refer to Figure 10 As shown, the orthographic projection of the fire extinguishing component 3 on the side wall 101 of the housing where the pressure relief hole 6 is located covers the entire pressure relief hole 6. Figure 9 and Figure 10 All views are taken from the orthographic projection of the fire extinguishing device 3 onto the side wall 101 of the housing where the pressure relief hole 6 is located. To facilitate viewing the pressure relief hole 6, the obscured edges of the pressure relief hole 6 are not depicted with dashed lines. The centerline of the fire extinguishing device 3 may or may not coincide with the axis of the pressure relief hole 6.

[0040] To ensure effective pressure relief, the centerline of the flame arrestor hole 301 is parallel to the axis of the pressure relief hole 6, such as... Figure 11 As shown, this reduces the path length of airflow through the flame-arresting through-hole 301. The above structural design provides better pressure relief but relatively poorer flame-arresting effect.

[0041] To ensure a good flame-retardant effect, the center line of the flame-retardant through-hole 301 is not parallel to the axis of the pressure relief hole 6, such as... Figure 12 As shown, the path length of the airflow through the flame arrestor hole 301 is extended, resulting in a better flame arresting effect, but a correspondingly poorer pressure relief effect. Furthermore, to improve the pressure relief effect, the flame arrestor hole 301 includes a distal end far from the pressure relief hole 6 and a proximal end close to the pressure relief hole 6. The centerline of the flame arrestor hole 301 is inclined towards the center of the pressure relief hole 6 from the distal end to the proximal end, resulting in a better pressure relief effect.

[0042] Among them, the thickness of fire extinguishing component 3 is b, such as Figure 12As shown, the range of b is 0.5mm ≤ b ≤ 25mm. Specifically, the value of b can be any value among 0.5mm, 2mm, 8mm, 15mm, and 25mm, or a value between any two values. Using the above-mentioned range for the thickness b of the fire extinguishing element 3 ensures both effective fire extinguishing and reduced impact on pressure relief. A larger thickness b of the fire extinguishing element 3 results in a longer length of the flame-arresting through-hole 301 along its thickness direction, leading to a longer path for gas molecules to collide with the hole wall, thus improving the fire extinguishing effect. However, this also increases the impact on pressure relief, increasing exhaust resistance. A smaller thickness b of the fire extinguishing element 3, while reducing the impact on airflow pressure relief, still affects the fire extinguishing effect.

[0043] 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.

[0044] To improve fire extinguishing effectiveness, the fire extinguishing element 3 is configured with multiple layers. 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 valve 2, and the fire extinguishing element 3 with the smallest flame-arresting through-hole 301 is placed closer to the pressure relief valve 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.

[0045] The battery pack pressure relief mechanism of this utility model limits the range of the cross-sectional area s of the flame-arresting through hole 301, the range of the porosity a on the fire extinguishing component 3, and the range of a×s, which can ensure both pressure relief and flame-arresting effects, thereby improving the safety performance of the battery pack.

[0046] 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.

[0047] 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.

[0048] 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 pressure relief mechanism comprising a pressure relief valve installed at a pressure relief hole position on a side wall of a case of a battery pack, the pressure relief hole communicating with a pressure relief cavity of the battery pack, and a fire extinguishing member disposed between the pressure relief valve and the pressure relief cavity, and the fire extinguishing member being provided corresponding to the pressure relief hole, characterized in that, The fire extinguishing device is provided with multiple fire-arresting through holes for fire prevention. The cross-sectional area of ​​each fire-arresting through hole is s, and the porosity of the fire extinguishing device is a, where a × s is in the range of 0.04 mm. 2 ≤a×s≤2.5mm 2 .

2. The battery pack pressure relief mechanism of claim 1, wherein, The fire barrier through hole is a circular hole, a x s is in the range of 0.08mm 2 ≤a x s≤2.5mm 2 .

3. The battery pack pressure relief mechanism according to claim 1, characterized in that, The fire barrier through hole is a square hole, a x s is in the range of 0.04mm 2 ≤a x s≤2.0mm 2 .

4. The battery pack pressure relief mechanism of claim 1, wherein, The orthographic projection of the fire extinguishing device on the side wall of the housing where the pressure relief hole is located coincides with the pressure relief hole.

5. The battery pack pressure relief mechanism according to claim 1, characterized in that, The pressure relief hole is at least partially covered by the orthographic projection of the fire extinguishing component on the side wall of the housing where the pressure relief hole is located; The centerline of the fire extinguishing device may or may not coincide with the axis of the pressure relief hole.

6. The battery pack pressure relief mechanism of claim 5, wherein, The pressure relief hole is completely covered by the orthographic projection of the fire extinguishing component on the side wall of the housing where the pressure relief hole is located.

7. The battery pack pressure relief mechanism of claim 1, wherein, The center line of the flame arrestor hole is parallel to the axis of the pressure relief hole.

8. The battery pack pressure relief mechanism of claim 1, wherein, The centerline of the flame arrestor hole is not parallel to the axis of the pressure relief hole.

9. The battery pack pressure relief mechanism of claim 8, wherein, The flame-arresting through-hole includes a distal end away from the pressure relief hole and a proximal end close to the pressure relief hole. The centerline of the flame-arresting through-hole is inclined from the distal end to the proximal end toward the center of the pressure relief hole.

10. The battery pack pressure relief mechanism of claim 1, wherein, The fire extinguishing device is a metal mesh plate, and the thickness of the fire extinguishing device is b, wherein 0.5mm≤b≤25mm.

11. The battery pack pressure relief mechanism according to claim 1, characterized in that, The cross-sectional area s of the fire barrier through hole ranges from 0.19 mm 2 ≤ s ≤ 3.2 mm 2 The porosity a on the fire extinguishing member ranges from 0.2 ≤ a ≤ 0.95.

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