An exhaust filtration system for a battery pack

Abstract

The present invention discloses an exhaust filtration system for a battery pack, including an explosion-proof valve and a filter device, one end of the explosion-proof valve is connected to the battery pack, and the other end of the explosion-proof valve is connected to the filter device, the filter device includes an input port, an output port, a shell and a filter mechanism, the input port and the output port are respectively arranged at the two ends of the shell, the filter mechanism is arranged in the shell, and a plurality of filter holes are opened on the filter mechanism. Beneficial effect: Through the optimized design of the new explosion-proof valve and the new filter device, the technical solution of the present application is more widely applicable, and both large-capacity batteries and small-capacity batteries can well solve the problem of fire induced after thermal runaway, the exhaust is smoother, the filtering effect is better, and the subsequent treatment effect of thermal runaway of the battery pack is better.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal runaway of battery packs, and in particular to an exhaust filtration system for a battery pack. Background Art

[0002] On May 12, 2020, the three mandatory national standards GB 18384-2020 "Safety Requirements for Electric Vehicles", GB 38032-2020 "Safety Requirements for Electric Buses" and GB 30381-2020 "Safety Requirements for Power Batteries for Electric Vehicles" (hereinafter referred to as the "Three Mandatory Standards") organized and formulated by the Ministry of Industry and Information Technology were approved and issued by the State Administration for Market Regulation and the National Standards Administration, and will come into effect on January 1, 2021.

[0003] The three mandatory standards stipulate that after a battery cell experiences thermal runaway, the battery system will not catch fire or explode within 5 minutes. The requirement to reserve safe escape time for passengers has become a mandatory standard, which puts forward higher requirements for the safety of new energy vehicles. Suppressing thermal runaway of ternary batteries to meet the requirements of the three mandatory standards has become a difficult problem that needs to be solved in the field of new energy vehicle safety.

[0004] The existing post-treatment technical solutions for thermal runaway are either discharged to the outside by an exhaust pipe alone, or composed of an exhaust pipe and an explosion-proof valve, or composed of an exhaust pipe and a filter device, and the filter device uses a neutralizer or adsorbent (such as a coarse particle separation layer, an activated carbon layer, a potassium permanganate layer, an activated alumina layer, and a particulate filter layer) to filter the flue gas. Among the above-mentioned treatment technical solutions, the last one containing a filter device has a relatively better treatment effect in practice. However, this method also has limitations. When the battery capacity is small (such as 20Ah capacity) and the thermal runaway reaction is mild, this method can play a filtering role. When a large-capacity battery cell has a thermal runaway (such as a capacity greater than 40Ah), especially a ternary battery generates a large amount of smoke, burns violently, and the exhaust smoke pressure is very high. The filtering method of the neutralizer or adsorbent will have a serious hindering effect on the emission of smoke, resulting in excessive pressure to damage the filter device and even cause the power battery pack box to burst. The burning solid particles are ejected from the bursting point and ignite the ejected combustible gas, causing the fire to spread rapidly.

[0005] Therefore, how to solve the subsequent processing of thermal runaway of large-capacity batteries or battery modules is an issue that current technicians urgently need to study, in order to ensure that the large amount of smoke generated instantly is discharged smoothly and avoid damage to the filtering device or even the battery pack structure. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an exhaust filtration system for a battery pack. Through the optimized design of a new explosion-proof valve and a new filtering device, the technical solution of the present application is more widely applicable. Whether it is a large-capacity battery or a small-capacity battery, the problem of fire induced by thermal runaway can be well solved. The exhaust is smoother, the filtering effect is better, and the subsequent treatment effect of thermal runaway of the battery pack is better.

[0007] The objective of the present invention is achieved through the following technical measures: An exhaust filtration system for a battery pack, comprising an explosion-proof valve and a filtering device, wherein one end of the explosion-proof valve is connected to the battery pack, and the other end of the explosion-proof valve is connected to the filtering device, wherein the filtering device comprises an input port, an output port, a shell and a filtering mechanism, wherein the input port and the output port are respectively arranged at two ends of the shell, the filtering mechanism is arranged in the shell, and a plurality of filtering holes are opened on the filtering mechanism.

[0008] Furthermore, the filtering mechanism includes a first filter plate assembly and a second filter plate assembly, and the first filter plate assembly and the second filter plate assembly are arranged on both sides of the conveying direction of the filtering mechanism. The first filter plate assembly includes at least two first filter plates arranged at intervals, and the second filter plate assembly includes at least two second filter plates arranged at intervals. In the conveying direction of the filtering mechanism, at least two first filter plates are arranged from large to small according to the aperture size of the filter holes, and at least two second filter plates are arranged from large to small according to the aperture size of the filter holes.

[0009] Furthermore, in a conveying direction perpendicular to the filtering mechanism, a gap is provided between the first filter plate and the second filter plate that is closest thereto, and the gap is used for the passage of smoke when the battery pack thermally runs away.

[0010] Furthermore, the sum of the air permeability area of ​​the aperture on a single first filter plate, the air permeability area of ​​the aperture on the adjacent second filter plate and the effective air permeability area of ​​a single gap constitutes a single-layer air permeability area of ​​the filter mechanism, and the single-layer air permeability area is larger than the cross-sectional area of ​​the input port.

[0011] Furthermore, the effective air permeability area of ​​the slit is larger than the cross-sectional area of ​​the input port.

[0012] Furthermore, an angle is provided between the first filter plate and the side wall in the length direction of the shell, the angle of the angle is greater than 0° and less than 180°, the air permeability area of ​​the first filter plate is greater than the cross-sectional area of ​​the input port, and an angle is provided between the second filter plate and the side wall in the length direction of the shell, the angle of the angle is greater than 0° and less than 180°, and the air permeability area of ​​the second filter plate is greater than the cross-sectional area of ​​the input port.

[0013] Furthermore, the minimum diameter of the filter hole is less than 0.428 mm.

[0014] Furthermore, the first filter plate adjacent to the input port completely covers the smoke straight path of the input port.

[0015] Furthermore, in the conveying direction of the filtering mechanism, the centers of the filtering holes on the two adjacent first filter plates are staggered, and the centers of the filtering holes on the two adjacent second filter plates are staggered.

[0016] Furthermore, the exhaust filtration system of the battery pack also includes an exhaust pipe, which is used to connect the explosion-proof valve and the filtering device.

[0017] Furthermore, the exhaust pipe is made of a high-pressure and high-temperature resistant material.

[0018] Furthermore, the exhaust pipe is made of stainless steel.

[0019] Furthermore, the cross-sectional area of ​​the exhaust pipe is less than or equal to the cross-sectional area of ​​the filter device.

[0020] Furthermore, the exhaust filtration system of the battery pack also includes a fire protection interface, which is connected to the output port of the filtering device.

[0021] Furthermore, the explosion-proof valve includes a frame, a sealing gasket and a waterproof breathable membrane, the sealing gasket and the waterproof breathable membrane are separately arranged on the frame, the sealing gasket is used for the sealing connection between the explosion-proof valve and the battery pack, and the waterproof breathable membrane is used for pressure relief when the battery pack has thermal runaway.

[0022] Compared with the prior art, the beneficial effects of the present invention are: an exhaust filtration system for a battery pack, through the optimized design of a new explosion-proof valve and a new filter device, the technical solution of the present application is more widely applicable, whether it is a large-capacity battery or a small-capacity battery, it can well solve the problem of fire induced after thermal runaway, the exhaust is smoother, the filtering effect is better, and the subsequent treatment effect of thermal runaway of the battery pack is better. Specifically, the waterproof and breathable membrane of the explosion-proof valve can smoothly discharge and release pressure after the explosion without clogging, and the water can be smoothly input into the battery pack after the fire interface is passed through the water. The new filter device, the first filter plate assembly and the second filter plate assembly, double filtration; the first filter plate and the second filter plate are staggered, and the filter holes of multiple first filter plates or multiple second filter plates are staggered, and another baffle filtration; the cross-sectional area of ​​the exhaust pipe is ≤ the cross-sectional area of ​​the filter device to ensure the pressure relief of instantaneous high-pressure flue gas. The single-layer air permeability area is larger than the cross-sectional area of ​​the input port, which is one of the means to ensure smooth exhaust. The air permeability area of ​​the aperture on the single first filter plate or the single second filter plate is larger than the cross-sectional area of ​​the input port, which is the second means to ensure smooth exhaust. The effective air permeability area of ​​the gap is larger than the cross-sectional area of ​​the input port, which is the third means to ensure smooth exhaust. Through the above three means, whether the filter hole is partially blocked or completely blocked, it can prevent high-pressure flue gas from leaking out of the filter device, thereby effectively avoiding damage and explosion of the battery pack or the filter device. The apertures on the filter plate are arranged from large to small in the direction of flue gas transmission, which can fully filter solid particles and sparks.

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the exhaust filtration system of the battery pack.

[0025] Figure 2 It is a structural diagram of an explosion-proof valve.

[0026] FIG. 3 is a schematic diagram of the structure of multiple embodiments (3A-3C) of the filtering device.

[0027] Figure 4 It is a schematic diagram of the effective air permeability area of ​​the gap.

[0028] Figure 5 This is a combustion test diagram of the explosion-proof valve when the 153Ah ternary battery is in thermal runaway.

[0029] Among them, 1. battery pack, 2. explosion-proof valve, 4. filter device, 3. exhaust pipe, 5. fire interface, 6. output port, 7. input port, 8. filter mechanism, 9. shell, 10. filter hole, 11. first filter plate assembly, 12. second filter plate assembly, 13. first filter plate, 14. second filter plate, 15. frame, 16. sealing gasket, 17. waterproof breathable membrane, 18. bolt hole. DETAILED DESCRIPTION

[0030] like Figures 1 to 5 As shown, an exhaust filtration system for a battery pack includes an explosion-proof valve 2 and a filter device 4, one end of the explosion-proof valve 2 is connected to the battery pack 1, and the other end of the explosion-proof valve 2 is connected to the filter device 4, the filter device 4 includes an input port 7, an output port 6, a shell 9 and a filter mechanism 8, the input port 7 and the output port 6 are respectively arranged at the two ends of the shell 9, the filter mechanism 8 is arranged in the shell 9, and a plurality of filter holes 10 are opened on the filter mechanism 8, and the minimum diameter of the filter hole 10 is less than 0.428 mm. The exhaust filtration system of the battery pack 1 also includes an exhaust pipe 3 and a fire interface 5, the exhaust pipe 3 is used for connecting the explosion-proof valve 2 and the filter device 4, and the fire interface 5 is connected to the output port 6 of the filter device 4. The fire interface 5 adopts a standard fire interface 5. When thermal runaway occurs, the filter device 4 buys enough time for the passengers to wait for the fire truck to arrive, so that the firefighters can directly and quickly connect the fire water to the fire interface 5. The filter holes 10 on the filter mechanism 8 can well ensure the release of a large burst pressure, especially the release of a large amount of smoke generated instantly by large-capacity batteries and battery modules, to avoid damage to the filter device 4 or even the structure of the battery pack 1. The filter holes 10 can be in the shape of a long strip, a round hole, a square hole, etc. The apertures of the multiple filter holes on a single first filter plate 13 or a single second filter plate 14 can be consistent or inconsistent, as long as the apertures are from large to small from front to back.

[0031] The filtering mechanism 8 includes a first filter plate assembly 11 and a second filter plate assembly 12, and the first filter plate assembly 11 and the second filter plate assembly 12 are arranged on both sides of the conveying direction of the filtering mechanism 8. The first filter plate assembly 11 includes at least two first filter plates 13 arranged at intervals, and the second filter plate assembly 12 includes at least two second filter plates 14 arranged at intervals. In the conveying direction of the filtering mechanism 8, at least two first filter plates 13 are arranged from large to small according to the aperture size of the filter holes 10, and at least two second filter plates 14 are arranged from large to small according to the aperture size of the filter holes 10. A plurality of filter holes 10 are provided on each first filter plate 13, and a plurality of filter holes 10 are also provided on each second filter plate 14. The apertures of the plurality of filter holes 10 on a single first filter plate 13 or a single second filter plate 14 can be the same, as long as the apertures of the parallel second filter plates 14 gradually decrease from front to back in the conveying direction of the filter mechanism 8, and the apertures of the parallel first filter plates 13 gradually decrease from front to back, thereby realizing step-by-step filtration of the second filter plate assembly 12 or the first filter plate assembly 11. The filter mechanism 8 near the input port 7 end of the filter device 4 adopts a larger aperture, which can block large solid particles, such as copper foil, plastic parts exploded and burned by the explosion-proof valve 2, etc. The smaller the aperture is towards the end of the conveying direction, the smaller the aperture can filter small solid particles, such as sparks, dust, etc. Through experiments with the technology of the present application, it was found that more than 95% of the solid particles ejected by the thermal runaway of the multi-cell battery had a particle size of ≥ 0.428mm. Therefore, in order to maximize the filtering effect of the filter device 4 and exhaust exhaust gas without solid particles, the aperture at the very end of the conveying direction in the filter device 4 is set to less than 0.428mm. In this way, the filter device 4 can not only filter large solid particles, sparks, dust, etc., but also release the larger explosion pressure generated by the thermal runaway of the battery pack 1 to ensure smooth exhaust of smoke.

[0032] At least two of the first filter plates 13 are arranged in parallel, and at least two of the second filter plates 14 are arranged in parallel. The specific number of the first filter plates 13 or the second filter plates 14 can be 3, 4, 5, etc. Regardless of the specific number of the first filter plates 13 or the second filter plates 14, the aperture of the first filter plate 13 or the second filter plate 14 at the end of the conveying direction of the filter mechanism 8 is less than 0.428 mm. The first filter plate 13 and the adjacent second filter plates 14 are arranged alternately, that is, a second filter plate 14 is inserted between two adjacent parallel first filter plates 13, but the second filter plate 14 is arranged on the opposite side of the first filter plate 13 connected to the shell 9, and the second filter plate 14 does not contact the first filter plate 13. Further, in the conveying direction perpendicular to the filter mechanism 8, a gap is provided between the first filter plate 13 and the closest second filter plate 14, and the gap is used for the passage of smoke when the battery pack 1 is thermally runaway.

[0033] The sum of the air permeability area S1 of the aperture on the single first filter plate 13, the air permeability area S2 of the aperture on the adjacent second filter plate 14 and the effective air permeability area S of the single gap constitutes the single-layer air permeability area S of the filter mechanism 8. t1 , the single layer air permeability area S t1 The cross-sectional area S3 of the input port 7 is larger than that of the input port 7. The input port 7 and the exhaust pipe 3 may have the same diameter, or they may have different diameters. When the diameters are different, if the exhaust pipe 3 is larger than the diameter of the input port 7, the single-layer air permeability area S t1 Correspondingly, it should be larger than the cross-sectional area S4 of the exhaust pipe 3. If the exhaust pipe 3 is smaller than the diameter of the input port 7, the single-layer air permeability area S t1 It is sufficient to be larger than the cross-sectional area S3 of the input port 7. Calculate the single-layer air permeability area S t1 , if it is assumed that the area of ​​a single aperture is n1, and a single first filter plate 13 or an adjacent second filter plate 14 is provided with 12 holes, the air permeability area of ​​a single aperture on the first filter plate 13 is S1 = 12*n1, and the air permeability area of ​​an aperture on the adjacent second filter plate 14 is S2 = 12*n1. The effective air permeability area of ​​the gap S, S t1 =12*2*n1+S. When the areas of the first filter plate 13 and the second filter plate 14 are constant, the number of holes can be set according to different pore diameters. 12 holes are only one embodiment of the first filter plate 13 or the adjacent second filter plate 14.

[0034] The effective air permeability area S of the slit is greater than the cross-sectional area S3 of the input port 7. The effective air permeability area S refers to the minimum cross-sectional area of ​​the smoke passing through the slit. The bottom edge ab of the first filter plate 13 in the length direction, the bottom edge ab extends in the length direction of the first filter plate 13 to the intersection line cd of the surface of the second filter plate 14. The effective air permeability area S is the plane area formed by the bottom edge ab and the intersection line cd, as shown in FIG. Figure 4 shown.

[0035] The first filter plate 13 and the side wall of the shell 9 in the length direction are provided with an angle β, 0°<β<180°, and the air permeability area of ​​a single first filter plate 13 is larger than the cross-sectional area of ​​the input port 7. The second filter plate 14 and the side wall of the shell 9 in the length direction are provided with an angle β, 0°<β<180°, and the air permeability area of ​​a single second filter plate 14 is larger than the cross-sectional area of ​​the input port 7. The cross-sectional area of ​​the input port 7 is the ejection area of ​​the smoke. Under the design that the air permeability area of ​​a single second filter plate 14 or a single first filter plate 13 is larger than the ejection area of ​​the smoke, the first-stage filtration of the ejected smoke can be achieved by a single first filter plate 13 or a second filter plate 14. When there are multiple first filter plates 13 or second filter plates 14, multi-stage filtration of the ejected smoke can be achieved, thereby ensuring the filtering effect.

[0036] The first filter plate 13 adjacent to the input port 7 completely covers the smoke straight path of the input port 7 to increase the effective filtering area of ​​the first filter plate 13 for the smoke. If it cannot be covered, the effective filtering area of ​​the first filter plate 13 for the smoke will be reduced. When the smoke straight path is between the first filter plate 13 and the adjacent second filter plate 14, that is, part of the smoke ejected from the input port 7 is filtered by the first filter plate 13, another part is filtered by the second filter plate 14, and another part may directly enter the filter mechanism 8 behind through the gap. Obviously, this method will waste part of the filtering area of ​​the first filter plate 13 and the second filter plate 14.

[0037] In the conveying direction of the filter mechanism 8, the filter holes 10 on the two adjacent first filter plates 13 are arranged with their centers staggered, and the filter holes 10 on the two adjacent second filter plates 14 are arranged with their centers staggered. The staggered arrangement of the hole centers prevents the smoke from passing directly through the two adjacent first filter plates 13, and also prevents the smoke from passing directly through the two adjacent second filter plates 14, ensuring that the smoke is deflected between the first filter plate assembly 11 and the second filter plate assembly 12 to achieve better filtration.

[0038] Taking the 153Ah ternary battery as an example, it was found through experiments that when the 153Ah ternary battery is in thermal runaway, the combustion is violent, and the temperature of the explosion-proof valve 3 port reaches up to 1022.20℃. Therefore, for large-capacity batteries, it is necessary to select the material of the exhaust pipe 3 for exhausting flue gas to better meet the requirements of exhausting flue gas. At the same time, the large amount of flue gas generated instantly will be accompanied by very high pressure, so the exhaust pipe 3 is preferably able to withstand high pressure. Based on the above characteristics of thermal runaway of large-capacity batteries, the exhaust pipe 3 is optimized to be made of stainless steel 304, which is resistant to high temperature and high pressure. Due to the excellent characteristics of stainless steel 304, the wall thickness can be made thinner while meeting the use requirements, reducing the overall weight of the exhaust filtration system and reducing costs.

[0039] The cross-sectional area S4 of the exhaust pipe 3 is ≤ the cross-sectional area S5 of the filter device 4 .

[0040] like Figure 2As shown, the explosion-proof valve 2 includes a frame 15, a sealing gasket 16 and a waterproof breathable membrane 17. The sealing gasket 16 is arranged on the four edges of the frame 15. A through channel is opened in the middle of the frame 15. The waterproof breathable membrane 17 for covering the channel is installed on the frame 15. The sealing gasket 16 is used for sealing connection between the explosion-proof valve 2 and the battery pack 1. The waterproof breathable membrane 17 is used for pressure relief when the battery pack 1 is thermally runaway. At least two bolt holes 18 are arranged on the four edges of the frame 15. The explosion-proof valve 2 is connected to the battery pack 1 through at least two bolt holes 18. A through hole is opened on the shell 9 of the battery pack 1. There is at least one through hole. The through hole matches the area of ​​the waterproof breathable membrane 17. The waterproof breathable membrane 17 can completely cover the through hole. In view of the fact that large-capacity batteries and battery modules will instantly generate a large amount of smoke, this application makes new improvements to the existing explosion-proof valve 2. The waterproof and breathable membrane 17 is waterproof and breathable, which well maintains the pressure balance inside and outside the battery pack 1. When thermal runaway occurs, the waterproof and breathable membrane 17 of the explosion-proof valve 2 is exploded, and the channel running through the middle of the frame 15 is opened. The exploded particles are discharged from the battery pack 1 smoothly and unobstructed through the channel, and the pressure is fully relieved to ensure smooth discharge of smoke. When there are multiple through holes, an explosion-proof valve 2 can be installed in each through hole, and the corresponding number of exhaust pipes can be uniformly connected to the filter device 4. Of course, one through hole can correspond to one filter device 4.

[0041] Embodiment 1 of the filter device, as shown in 3A, the left pipeline of the filter device 4 is the exhaust pipe 3 for the smoke inlet, the inlet is close to the 1 / 3 of the top of the filter device 4, and the first filter plate assembly 11 of the upper layer can cover the straight path of the smoke inlet. The right pipeline is the exhaust pipe 3 for the smoke outlet, and the outlet is close to the 1 / 3 of the bottom of the filter device 4. Similarly, the second filter plate assembly 12 of the lower layer can cover the straight path of the smoke outlet. The filter holes 10 of the first filter plate 13 at the input port 7 are long holes, and the other filter holes 10 are round holes, which can effectively isolate large pieces of copper foil, plastic blocks after the explosion-proof valve 2 bursts and burns, and sealing gaskets 16. Then the large pieces of solid will slide to the empty space at the bottom of the filter device 4. The filter holes 10 with gradually decreasing apertures are processed on the subsequent first filter plate 13 and the second filter plate 14 to achieve step-by-step filtering. The filter holes 10 on the front and rear filter plates are staggered, which can effectively enhance the filtering effect. The angle β between the first filter plate 13 and the top side wall of the shell 9 in the length direction is 45 degrees, and the angle β between the second filter plate 14 and the bottom side wall of the shell 9 in the length direction is 45 degrees. The first filter plate 13 and the second filter plate 14 are staggered vertically but not in contact with each other. A gap is left between the first filter plate 13 and the second filter plate 14. The effective air permeability area of ​​the gap is not less than the cross-sectional area S4 of the exhaust pipe 3, thereby ensuring the smooth flow of the exhaust pressure relief channel. Even if the first filter plate 13 and the second filter plate 14 are completely blocked by solid particles, smoke can be discharged smoothly.

[0042] In the embodiment 2 of the filter device, as shown in 3B, the first filter plate 13 and the second filter plate 14 are arranged at an angle of 135°, so that solid particles can be filtered and smoke can be discharged smoothly. The filter holes 10 are a combination of elongated holes and circular holes.

[0043] Embodiment 3 of the filter device, as shown in 3C: the first filter plate 13 and the second filter plate 14 are arranged alternately up and down, and the angle between the first filter plate 13 and the second filter plate 14 and the side wall of the housing 9 in the length direction is 90 degrees, which can also effectively isolate and filter solid particles, and the smoke is discharged smoothly. All the filter holes 10 are circular holes.

[0044] Pressure relief and discharge process: The waterproof and breathable membrane 17 of the explosion-proof valve 2 explodes under the action of a large amount of smoke generated by the thermal runaway of the battery pack 1. The smoke enters the filter device 4 along the exhaust pipe 3 from the channel of the explosion-proof valve 2, and is depressurized in the housing 9 of the filter device 4. After multi-stage filtration and baffle filtration by the first filter plate assembly 11 and the second filter plate assembly 12, the smoke is finally discharged through the fire interface 5 after full filtration without blockage. When the fire truck is connected to the fire interface 5, water enters the filter device 4 from the fire interface 5, enters the channel of the explosion-proof valve 2 through the filter holes 10 and gaps in the filter device 4, and finally enters the battery pack 1 to cool down and extinguish the fire.

[0045] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An exhaust filtration system for a battery pack, characterized in that: It includes an explosion-proof valve and a filtering device, one end of the explosion-proof valve is connected to the battery pack, and the other end of the explosion-proof valve is connected to the filtering device, the filtering device includes an input port, an output port, a shell and a filtering mechanism, the input port and the output port are respectively arranged at the two ends of the shell, the filtering mechanism is arranged in the shell, and a plurality of filtering holes are opened on the filtering mechanism; the filtering mechanism includes a first filter plate assembly and a second filter plate assembly, the first filter plate assembly and the second filter plate assembly are respectively arranged on both sides of the conveying direction of the filtering mechanism, the first filter plate assembly includes at least two first filter plates arranged at intervals, the second filter plate assembly includes at least two second filter plates arranged at intervals, in the conveying direction of the filtering mechanism, at least two first filter plates are arranged from large to small according to the aperture size of the filter holes, and at least two second filter plates are arranged from large to small according to the aperture size of the filter holes; in a direction perpendicular to the filtering mechanism In the conveying direction, a gap is provided between the first filter plate and the closest second filter plate, and the gap is used for the passage of smoke when the battery pack has thermal runaway; the sum of the air permeability area of ​​the aperture on a single first filter plate, the air permeability area of ​​the aperture on the adjacent second filter plate and the effective air permeability area of ​​a single gap constitutes a single-layer air permeability area of ​​the filter mechanism, and the single-layer air permeability area is larger than the cross-sectional area of ​​the input port; the effective air permeability area of ​​the gap is larger than the cross-sectional area of ​​the input port; in the conveying direction of the filter mechanism, the centers of the filter holes on the two adjacent first filter plates are staggered, and the centers of the filter holes on the two adjacent second filter plates are staggered; the exhaust filtration system of the battery pack also includes an exhaust pipe, which is used for connecting the explosion-proof valve and the filter device, and the cross-sectional area of ​​the exhaust pipe is ≤ the cross-sectional area of ​​the filter device.

2. The exhaust filtration system of the battery pack according to claim 1, characterized in that: An angle is formed between the first filter plate and the side wall in the length direction of the shell, and the angle is greater than 0° and less than 180°. The air permeability area of ​​the first filter plate is greater than the cross-sectional area of ​​the input port. An angle is formed between the second filter plate and the side wall in the length direction of the shell, and the angle is greater than 0° and less than 180°. The air permeability area of ​​the second filter plate is greater than the cross-sectional area of ​​the input port.

3. The exhaust filtration system of the battery pack according to claim 1, characterized in that: The minimum diameter of the filter hole is less than 0.428 mm.

4. The exhaust filtration system of the battery pack according to claim 1, characterized in that: The first filter plate adjacent to the input port completely covers the smoke straight path of the input port.

5. The exhaust filtration system of the battery pack according to claim 1, characterized in that: The exhaust pipe is made of high pressure and high temperature resistant material.

6. The exhaust filtration system of the battery pack according to claim 5, characterized in that: The exhaust pipe is made of stainless steel.

7. The exhaust filtration system of the battery pack according to claim 1, characterized in that: The exhaust filter system of the battery pack also includes a fire protection interface, which is connected to the output port of the filter device.

8. The exhaust filtration system of the battery pack according to claim 1, characterized in that: The explosion-proof valve includes a frame, a sealing gasket and a waterproof breathable membrane. The sealing gasket and the waterproof breathable membrane are separately arranged on the frame. The sealing gasket is used for sealing connection between the explosion-proof valve and the battery pack, and the waterproof breathable membrane is used for pressure relief when the battery pack has thermal runaway.

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