Battery pack smoke exhaust structure

Abstract

To provide a smoke exhaust structure of a battery pack capable of preventing foreign objects from entering a battery pack enclosure and capable of exhausting smoke while suppressing pressure loss when the battery pack heats up abnormally.SOLUTION: A vent valve 20 covers, in a breathable manner, an opening 26E communicating with the inside of the housing 14 by a flexible ventilation membrane 34 and discharges gas discharged from the battery stack to the outside of the housing 14. The gas discharged from the vent valve 20 is guided to a predetermined discharge location by an exhaust flue. The vent valve 20 is provided with a protrusion 30 with a gap on the side opposite to the inside of the housing 14 with respect to ventilation membrane 34. The protrusion 30 is arranged with the sharp tip 30A facing the ventilation membrane 34 and is configured to break through the air-permeable membrane 34 when the ventilation membrane 34 expands a predetermined amount due to an increase in the internal pressure of the housing 14.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a smoke exhaust structure for a battery pack. [Background technology]

[0002] The following Patent Document 1 discloses a smoke exhaust structure for a battery pack (cell pack) that houses a battery. Briefly, in this structure, one end of a smoke exhaust path is connected to the battery pack, and the other end of the smoke exhaust path is connected to the outside of the vehicle. The smoke exhaust path also includes a first flow path formed at the one end, a second flow path formed at the other end, and a throttled flow path provided between the first and second flow paths and having a flow path cross-sectional area smaller than those of the first and second flow paths. This structure makes it difficult for foreign matter to enter the battery pack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-149146 Summary of the Invention [Problem to be solved by the invention]

[0004] However, this structure leaves room for improvement in terms of suppressing pressure loss and discharging smoke when the battery pack generates abnormal heat.

[0005] Taking the above facts into consideration, the present invention aims to provide a smoke exhaust structure for a battery pack that can prevent foreign objects from entering the battery pack housing and can exhaust smoke while suppressing pressure loss when the battery pack generates abnormal heat. [Means for solving the problem]

[0006] The smoke exhaust structure for a battery pack of the present invention described in claim 1 is a smoke exhaust structure for a battery pack having a housing and a battery housed therein, the smoke exhaust structure comprising: an opening communicating with the inside of the housing is covered with a flexible breathable membrane in a breathable manner, the opening being connected to the inside of the housing, the breathable valve discharging gas from the battery to the outside of the housing; a smoke exhaust path guiding the gas discharged from the breathable valve to a predetermined discharge location; and a protrusion provided on the opposite side of the breathable membrane from the inside of the housing, the protrusion configured to pierce the breathable membrane when the breathable membrane expands by a predetermined amount due to an increase in internal pressure of the housing. The ventilation valve includes a base member in which the opening is formed and to which the ventilation membrane is attached, and the base member is connected to the outer periphery of the ventilation membrane and has a tapered portion that is arranged downstream of the ventilation membrane in the gas discharge direction and gradually reduces in diameter toward the downstream side in the gas discharge direction.

[0007] According to the above configuration, the vent valve ventilates the opening communicating with the inside of the housing with a flexible ventilation membrane, thereby discharging gas discharged from the battery to the outside of the housing. The ventilation membrane prevents foreign matter from entering the housing. The gas discharged from the vent valve is guided to a predetermined exhaust location via a smoke exhaust path. Meanwhile, a protrusion is provided on the side of the ventilation membrane opposite the inside of the housing, and this protrusion is configured to pierce the ventilation membrane when the ventilation membrane expands by a predetermined amount due to an increase in internal pressure of the housing. Therefore, when the internal pressure of the housing increases due to abnormal heat generation of the battery pack, the ventilation membrane expands by a predetermined amount and is pierced by the protrusion, thereby guiding and discharging smoke to a predetermined exhaust location while suppressing pressure loss. The vent valve also includes a base member with an opening formed therein and a vent membrane attached thereto. The base member is connected to the outer periphery of the vent membrane and is disposed downstream of the vent membrane in the gas discharge direction. The base member has a tapered portion that gradually narrows toward the downstream side in the gas discharge direction. This allows the vent membrane to have a large inflatable area while reducing the cross-sectional area of ​​the flow path downstream of the vent valve in the gas discharge direction without abruptly increasing pressure loss. When the inflatable membrane has a large inflatable area, it expands with greater force than when the inflatable membrane has a small inflatable area, resulting in a larger rupture area when the vent membrane is punctured by a protrusion. This further reduces pressure loss during abnormal heat generation in the battery pack. Furthermore, reducing the cross-sectional area of ​​the flow path downstream of the base member in the gas discharge direction allows the flue gas exhaust passage downstream of the vent valve in the gas discharge direction to have a smaller cross-sectional area, thereby increasing flexibility in installation.

[0008] The smoke exhaust structure for a battery pack of the present invention described in claim 2 is a smoke exhaust structure for a battery pack having a housing and a battery housed therein, the smoke exhaust structure comprising: an opening communicating with the inside of the housing is covered with a flexible breathable membrane to allow ventilation; a vent valve that exhausts gas exhausted from the battery to the outside of the housing; a smoke exhaust path that guides the gas exhausted from the vent valve to a predetermined exhaust location; and a protrusion that is provided on the opposite side of the housing from the inside of the breathable membrane with a gap therebetween and that is arranged with a sharp tip facing the breathable membrane side. The ventilation valve includes a base member in which the opening is formed and to which the ventilation membrane is attached, and the base member is connected to the outer periphery of the ventilation membrane and has a tapered portion that is arranged downstream of the ventilation membrane in the gas discharge direction and gradually reduces in diameter toward the downstream side in the gas discharge direction.

[0009] According to the above configuration, the vent valve covers the opening communicating with the inside of the housing with a flexible ventilation membrane to allow ventilation, and discharges gas discharged from the battery to the outside of the housing. The ventilation membrane can prevent foreign matter from entering the housing. The gas discharged from the vent valve is guided to a predetermined discharge location through a smoke exhaust path. Meanwhile, a protrusion is provided on the opposite side of the housing from the inside of the housing, with a gap between them, and the protrusion is positioned with its sharp tip facing the ventilation membrane. Therefore, when the internal pressure of the housing increases due to abnormal heat generation in the battery pack, the ventilation membrane expands by a predetermined amount and is pierced by the protrusion, thereby guiding and discharging smoke to a predetermined discharge location while minimizing pressure loss. The vent valve also includes a base member with an opening formed therein and a vent membrane attached thereto. The base member is connected to the outer periphery of the vent membrane and is disposed downstream of the vent membrane in the gas discharge direction. The base member has a tapered portion that gradually narrows toward the downstream side in the gas discharge direction. This allows the vent membrane to have a large inflatable area while reducing the cross-sectional area of ​​the flow path downstream of the vent valve in the gas discharge direction without abruptly increasing pressure loss. When the inflatable membrane has a large inflatable area, it expands with greater force than when the inflatable membrane has a small inflatable area, resulting in a larger rupture area when the vent membrane is punctured by a protrusion. This further reduces pressure loss during abnormal heat generation in the battery pack. Furthermore, reducing the cross-sectional area of ​​the flow path downstream of the base member in the gas discharge direction allows the flue gas exhaust passage downstream of the vent valve in the gas discharge direction to have a smaller cross-sectional area, thereby increasing flexibility in installation.

[0010] The smoke exhaust structure for a battery pack of the present invention as set forth in claim 3 comprises: a gas exhaust valve that covers an opening communicating with the interior of the housing with a flexible breathable membrane to allow ventilation and that exhausts gas exhausted from the battery to the outside of the housing; a smoke exhaust path that guides the gas exhausted from the breathable valve to a predetermined exhaust location; and a protrusion that is provided on the opposite side of the housing from the inside of the housing with respect to the breathable membrane and is configured to pierce the breathable membrane when the breathable membrane expands by a predetermined amount due to an increase in internal pressure of the housing, the gas vent valve having a base member that has the opening formed therein and to which the breathable membrane is attached, the base member having a gas flow path forming portion that forms a flow path for the gas, and a bridging portion that is bridged inside the gas flow path forming portion and is positioned opposite a part of the breathable membrane without blocking the gas flow path, and the protrusion is provided on the bridging portion.

[0011] According to the above configuration, The vent valve covers an opening communicating with the inside of the housing with a flexible ventilation membrane to allow ventilation and discharge gas discharged from the battery to the outside of the housing. The ventilation membrane prevents foreign matter from entering the housing. The gas discharged from the vent valve is directed to a predetermined discharge location via a smoke exhaust path. Meanwhile, a protrusion is provided on the opposite side of the ventilation membrane from the inside of the housing, and this protrusion is configured to pierce the ventilation membrane when the ventilation membrane expands by a predetermined amount due to an increase in internal pressure of the housing. Therefore, when the internal pressure of the housing increases due to abnormal heat generation of the battery pack, the ventilation membrane expands by a predetermined amount and is pierced by the protrusion, resulting in the smoke being directed to the predetermined discharge location and discharged while minimizing pressure loss. The vent valve further includes a base member having an opening formed therein and a ventilation membrane attached thereto, the base member having a gas flow path forming portion that forms a gas flow path, and a bridging portion that is bridged inside the gas flow path forming portion and is disposed opposite a part of the ventilation membrane without blocking the gas flow path, and the protrusion is provided on the bridging portion. As a result, the positional accuracy of the protrusion relative to the ventilation membrane can be easily ensured, and the protrusion can be stably supported despite the simple configuration, so that the ventilation membrane that has expanded to a predetermined amount can be stably broken through by the protrusion.

[0012] The smoke exhaust structure for a battery pack of the present invention as set forth in claim 4 comprises: A smoke exhaust structure for a battery pack having batteries housed in a housing, the structure comprising: a vent valve that covers an opening communicating with the inside of the housing with a flexible breathable membrane to allow ventilation and exhausts gas exhausted from the battery to the outside of the housing; a smoke exhaust path that guides the gas exhausted from the vent valve to a predetermined exhaust location; and a protrusion that is provided on the opposite side of the housing from the inside of the vent membrane with a gap and is arranged with its sharp tip facing the breathable membrane side, the vent valve having a base member in which the opening is formed and on which the breathable membrane is attached, the base member having a gas flow path forming portion that forms a flow path for the gas, and a bridging portion that is bridged inside the gas flow path forming portion and is arranged opposite a part of the breathable membrane without blocking the gas flow path, the protrusion being provided on the bridging portion.

[0013] According to the above configuration, The vent valve covers an opening communicating with the inside of the housing with a flexible ventilation membrane to allow ventilation, and discharges gas discharged from the battery to the outside of the housing. The ventilation membrane prevents foreign matter from entering the housing. The gas discharged from the vent valve is directed to a predetermined discharge location via a smoke exhaust path. Meanwhile, a protrusion is provided on the opposite side of the housing from the inside of the housing, with a gap between them, with the protrusion facing the ventilation membrane. Therefore, when the internal pressure of the housing increases due to abnormal heat generation in the battery pack, the ventilation membrane expands by a predetermined amount and is pierced by the protrusion, thereby guiding the smoke to the predetermined discharge location while minimizing pressure loss. The vent valve further includes a base member having an opening formed therein and a ventilation membrane attached thereto, the base member having a gas flow path forming portion that forms a gas flow path, and a bridging portion that is bridged inside the gas flow path forming portion and is disposed opposite a part of the ventilation membrane without blocking the gas flow path, and the protrusion is provided on the bridging portion. As a result, the positional accuracy of the protrusion relative to the ventilation membrane can be easily ensured, and the protrusion can be stably supported despite the simple configuration, so that the ventilation membrane that has expanded to a predetermined amount can be stably broken through by the protrusion.

[0016] Claim 5 The smoke exhaust structure of the battery pack of the present invention described in claim 3 or claim 4 In the described configuration, the bridge portion is shaped like a cross that intersects at the center of the flow path when looking at the inside of the gas flow path forming portion in the direction of gas discharge, and the protrusion portion is provided at the intersection of the bridge portion.

[0017] According to the above configuration, the protrusions can be supported more stably and can be brought into contact with the vicinity of the bulging top of the expanded breathable membrane, thereby enabling the protrusions to more stably break through the breathable membrane that has expanded to a predetermined extent. [Effects of the Invention]

[0018] As described above, the smoke exhaust structure for a battery pack of the present invention has the excellent effect of preventing foreign objects from entering the battery pack housing and of allowing smoke to be exhausted while suppressing pressure loss when the battery pack generates abnormal heat. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing the overall configuration of a battery pack to which a smoke exhaust structure for a battery pack according to one embodiment of the present invention is applied; [Figure 2] FIG. 2 is an exploded perspective view showing the main part of the vent valve of FIG. 1. [Figure 3] 3 is an enlarged cross-sectional view showing an assembled state of the components of FIG. 2, cut at a position corresponding to line 3-3 in FIG. 2. FIG. [Figure 4] 2 is a simplified front view showing a base member to which a ventilation membrane is attached in the ventilation valve of FIG. 1. FIG. [Figure 5] 3 is an enlarged perspective view showing the protrusion of FIG. 2 and the surrounding area on the base end side thereof. FIG. [Figure 6] 6A and 6B are cross-sectional side views schematically illustrating changes in the state of the breathable membrane of Fig. 2. Fig. 6A shows the breathable membrane in an unexpanded state, and Fig. 6B shows the breathable membrane in an expanded state. [Figure 7] FIG. 10 is a perspective view showing a modified example of the protrusion and the surrounding area on the base end side thereof. [Figure 8] FIG. 10 is a perspective view showing another modified example of the protrusion and the surrounding portion on the base end side thereof. [Figure 9] 9 is an enlarged cross-sectional view showing a state cut along line 9-9 in FIG. 8. FIG. [Figure 10] FIG. 10 is a simplified front view showing a base member to which a ventilation membrane is attached in a ventilation valve according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] A smoke exhaust structure for a battery pack according to one embodiment of the present invention will be described with reference to Figures 1 to 6. Note that a battery pack 10 (see Figure 1) according to this embodiment is an auxiliary power supply mounted on an autonomous vehicle (not shown) that runs on electricity. In other words, this battery pack 10 is a backup power supply that enables the autonomous vehicle to travel a certain distance even if the battery stack (not shown), which serves as the main power supply, stops functioning due to a malfunction or the like.

[0021] For ease of explanation, the arrow UP shown in each figure indicates the upward direction of the battery pack 10, the arrow FR indicates the forward direction of the battery pack 10, and the arrow RH indicates the rightward direction of the battery pack 10. Therefore, in the following explanation, when the directions of up / down, front / back, and left / right are mentioned without special mention, they refer to up / down in the up / down direction of the battery pack 10, front / back in the front / back direction of the battery pack 10, and left / right in the left / right direction of the battery pack 10.

[0022] (Configuration of the embodiment) Fig. 1 is a perspective view showing the overall configuration of a battery pack 10 to which the smoke exhaust structure for a battery pack according to this embodiment is applied. As shown in Fig. 1, the battery pack 10 according to this embodiment has a battery stack 12 (shown simply by dotted lines in the drawing) as a battery, and a housing 14 that houses the battery stack 12.

[0023] The battery stack 12 is configured to include multiple battery cells. The housing 14 is made of resin and is formed in a substantially rectangular parallelepiped shape, and is, for example, longer left-to-right than it is front-to-back. The housing 14 includes a case 16, a top cover member 17 capable of closing an opening (not shown) formed in the top of the case 16, and a side cover member 18 capable of closing an opening (not shown) formed in one side (right side) of the case 16. An O-ring (not shown) is provided between the top cover member 17 and the upper end of the case 16, and another O-ring (not shown) is provided between the side cover member 18 and the right side of the case 16. This provides a structure in which the housing 14 containing the battery stack 12 is sealed in a waterproof and dustproof state.

[0024] The side cover member 18 includes a plate-shaped side cover main body 18A. An opening 18B is formed through the bottom of the side cover main body 18A, and a frame-shaped portion 18C is formed on the outer periphery of the opening 18B and protrudes outward from the housing 14. A vent valve 20 is disposed inside the frame portion 18C, and this vent valve 20 is attached to the side cover main body 18A side. The vent valve 20 has the function of discharging gases such as carbon monoxide (CO) discharged from the battery stack 12 to the outside of the housing 14.

[0025] One end of a smoke exhaust hose 42 is connected to the vent valve 20. A grommet 44 is provided at the other end of the smoke exhaust hose 42. The smoke exhaust hose 42 and the grommet 44 form a smoke exhaust path 40 that guides the gas exhausted from the vent valve 20 to a predetermined exhaust location (outside the vehicle in this embodiment).

[0026] Next, a detailed description will be given of the vent valve 20. In the following description, the side of the vent valve 20 that communicates with the inside of the housing 14 will be referred to as the upstream side in the gas discharge direction (hereinafter referred to as the "upstream side" where appropriate), and the side of the vent valve 20 that communicates with the smoke exhaust hose 42 will be referred to as the downstream side in the gas discharge direction (hereinafter referred to as the "downstream side" where appropriate).

[0027] Fig. 2 shows an exploded perspective view of the main parts of the vent valve 20, and Fig. 3 shows an enlarged cross-sectional view of the assembled state of the components shown in Fig. 2, taken at a position corresponding to line 3-3 in Fig. 2. As shown in Figs. 2 and 3, the vent valve 20 is composed of a base member 22, a ventilation membrane 34 attached to the upstream side of the base member 22, and a cap 36 attached to the downstream side of the base member 22.

[0028] The cap 36 is formed in the shape of a short tube with a straight central axis, and includes a first cylindrical portion 36A that forms one side in the axial direction of the tube, and a second cylindrical portion 36C that forms the other side in the axial direction and has a larger diameter than the first cylindrical portion 36A. The upstream end of the first cylindrical portion 36A and the downstream end of the second cylindrical portion 36C are connected along the entire circumference by a step portion 36B. A protruding portion 36D that protrudes radially outward is formed along the entire circumference of the outer periphery of the downstream end of the first cylindrical portion 36A. One end of a smoke exhaust hose 42 (see FIG. 1) is attached to the outer periphery of the first cylindrical portion 36A.

[0029] The base member 22 is a member that penetrates in the same direction as the attached cap 36, and has a gas flow path forming portion 22A that forms a gas flow path 22F. The gas flow path forming portion 22A includes a cylindrical cap mounting tube 24 to which the cap 36 is attached, and an upstream base portion 26 that is formed continuously with the upstream side of the cap mounting tube 24. As shown in FIG. 3 , a second cylindrical portion 36C of the cap 36 is disposed on the outer periphery of the cap mounting tube 24, and a seal member 38 is interposed in the gap between the cap mounting tube 24 and the cap 36.

[0030] The outer surface of the upstream base portion 26 has an outer peripheral surface 26B that is larger in diameter than the outer surface 24A of the cap mounting cylindrical portion 24, and a stepped surface 26A that connects the outer peripheral surface 26B to the outer surface 24A of the cap mounting cylindrical portion 24. The second cylindrical portion 36C of the cap 36 abuts against the stepped surface 26A. The upstream base portion 26 also has a flange portion 26F that protrudes radially outward from near the upstream end of the outer peripheral surface 26B.

[0031] The inner surface of the upstream base portion 26 includes a tapered portion 26D that is continuous with the base end of the flange portion 26F and gradually reduces in diameter downstream in the gas discharge direction, and an inner circumferential surface 26C of a constant diameter that is continuous with the end of the tapered portion 26D on the reduced diameter side. The end of the tapered portion 26D connected to the flange portion 26F defines an opening 26E on the gas inlet side. The opening 26E formed in the upstream base portion 26 is positioned to communicate with the interior of the housing 14. The inner circumferential surface 26C of the upstream base portion 26 is continuous with the inner surface 24B of the cap mounting tube portion 24 and has the same inner diameter as the inner diameter of the cap mounting tube portion 24.

[0032] As shown in Fig. 2, a protrusion 26G is formed on the upstream surface of flange portion 26F, protruding around the entire circumference on the outer periphery of opening 26E. As shown in Fig. 3, an air permeable membrane 34 that covers opening 26E in a breathable manner is attached to the upstream surface of flange portion 26F, on the inner periphery side of protrusion 26G. Fig. 4 shows a simplified front view (with protrusion 26G omitted) of base member 22 to which air permeable membrane 34 is attached. As shown in Fig. 4, opening 26E and air permeable membrane 34 are formed in a circular shape when viewed from the front, as an example.

[0033] 3 and 4 is a flexible film that can expand to become convex toward the downstream side when the internal pressure of the housing 14 (see FIG. 1) increases (see the schematic diagram in FIG. 6(B)). Also, as shown in FIG. 3, the tapered portion 26D described above is connected to the outer periphery of the gas permeable film 34 at its upstream end.

[0034] 2 is bridged inside the gas flow path forming portion 22A, inside a portion formed by the inner circumferential surface 26C of the upstream base portion 26 and the inner surface 24B of the cap mounting cylinder portion 24. The bridge portion 28 is formed in a cross shape that intersects at the center of the flow path 22F when the inside of the gas flow path forming portion 22A is viewed in the gas discharge direction, and is disposed opposite a part of the gas permeable membrane 34.

[0035] A protrusion 30 is provided at the intersection 28A of the bridging portion 28. FIG. 5 shows an enlarged perspective view of the protrusion 30 and the surrounding area on the base end side thereof. As shown in FIG. 5, the protrusion 30 is formed in a conical shape, for example. As shown in FIG. 3, the protrusion 30 is provided with a gap on the side opposite the inside of the housing 14 with respect to the gas permeable membrane 34, and is configured to pierce the gas permeable membrane 34 when the gas permeable membrane 34 expands by a predetermined amount due to an increase in the internal pressure of the housing 14. In other words, the protrusion 30 is arranged with its sharp tip 30A facing the gas permeable membrane 34 side.

[0036] (Actions and Effects of the Embodiments) Next, the operation and effects of the above embodiment will be described.

[0037] According to the above configuration, the vent valve 20 has the opening 26E communicating with the inside of the housing 14 covered with the flexible ventilation membrane 34 in a ventilation manner, and discharges gas discharged from the battery stack 12 (see FIG. 1) to the outside of the housing 14. The ventilation membrane 34 can prevent foreign matter from entering the housing 14. The gas discharged from the vent valve 20 is also guided by the smoke exhaust path 40 (see FIG. 1) to the outside of the vehicle, which is the designated discharge location.

[0038] Meanwhile, a protrusion 30 is provided with a gap between the gas permeable membrane 34 and the inside of the housing 14, and the protrusion 30 is disposed with its sharp tip 30A facing the gas permeable membrane 34. Therefore, when the gas permeable membrane 34 in the state shown in the schematic cross-sectional view of FIG. 6(A) receives pressure F due to an increase in the internal pressure of the housing 14 and expands as shown in FIG. 6(B), the gas permeable membrane 34 approaches the tip 30A of the protrusion 30, and as the gas permeable membrane 34 further expands, the protrusion 30 breaks through the gas permeable membrane 34 (not shown). That is, when the internal pressure of the housing 14 increases due to abnormal heat generation in the battery pack 10 (see FIG. 1), the gas permeable membrane 34 expands by a predetermined amount and is broken through by the protrusion 30, thereby opening the valve. As a result, the smoke can be guided and discharged to the outside of the vehicle through the smoke exhaust path 40 shown in FIG. 1 while suppressing pressure loss.

[0039] To provide further explanation, in the battery pack 10, the casing 14 houses the battery stack 12 in a sealed state, and therefore the pressure inside the casing 14 needs to be adjusted in response to temperature changes inside the casing 14. Furthermore, if an abnormality occurs in a battery cell of the battery stack 12 and smoke is generated, the smoke needs to be exhausted from inside the casing 14 to prevent an increase in internal pressure within the casing 14, and the smoke needs to be exhausted outside the vehicle cabin to prevent the smoke from being released into the vehicle cabin. In contrast, in this embodiment, under normal circumstances, the ventilation membrane 34 shown in FIG. 3 allows ventilation between the inside and outside of the casing 14, and in the event of an abnormality, the ventilation membrane 34 can be broken to exhaust the smoke outside the vehicle cabin through the smoke exhaust path 40 (see FIG. 1) while suppressing pressure loss.

[0040] Furthermore, in this embodiment, the base member 22 to which the ventilation membrane 34 is attached has a tapered portion 26D that is connected to the outer periphery of the ventilation membrane 34 and gradually reduces in diameter toward the downstream side in the gas discharge direction. This allows the area of ​​the inflatable range of the ventilation membrane 34 to be set large while reducing the flow path cross-sectional area on the downstream side (outlet side) of the ventilation valve 20 in the gas discharge direction without a sudden increase in pressure loss. When the area of ​​the inflatable range of the ventilation membrane 34 is set large, the ventilation membrane 34 expands with greater force than when the area of ​​the inflatable range of the ventilation membrane 34 is small, and the rupture portion becomes larger when the ventilation membrane 34 is punctured by the protrusion 30. This more effectively reduces pressure loss during abnormal heat generation in the battery pack 10 (see FIG. 1 ). Furthermore, reducing the flow path cross-sectional area on the downstream side in the gas discharge direction of the base member 22 allows the flue gas exhaust channel 40 (see FIG. 1 ), which is downstream of the ventilation valve 20 in the gas discharge direction, to have a smaller flow path cross-sectional area, thereby increasing the flexibility of installation.

[0041] In addition, in this embodiment, the protrusion portion 30 is provided on the base member 22 in which the opening 26E is formed in the ventilation valve 20 and the ventilation membrane 34 is attached, so that the positional accuracy of the protrusion portion 30 relative to the ventilation membrane 34 can be easily ensured.

[0042] 2, the base member 22 has a gas flow path forming portion 22A that forms the gas flow path 22F, and a bridge portion 28 that spans the inside of the gas flow path forming portion 22A and is disposed opposite a part of the gas permeable membrane 34, and the protrusion portion 30 is provided on the bridge portion 28. Therefore, the protrusion portion 30 can be stably supported despite the simple configuration.

[0043] Furthermore, in this embodiment, the bridging portion 28 is formed in a cross shape that intersects at the center of the flow path 22F when the inside of the gas flow path forming portion 22A is viewed in the gas discharge direction, and the protrusion 30 is provided at the intersecting portion 28A of the bridging portion 28. This allows the protrusion 30 to be supported more stably, and the protrusion 30 can be brought into contact with the vicinity of the bulging top of the expanded gas permeable membrane 34. This allows the protrusion 30 to more stably break through the gas permeable membrane 34 that has expanded to a predetermined amount.

[0044] As described above, the smoke exhaust structure of the battery pack of this embodiment can prevent foreign objects from entering the housing 14 of the battery pack 10 shown in Figure 1, and can also exhaust smoke while suppressing pressure loss when the battery pack 10 abnormally heats up.

[0045] (Variation) Next, some modified examples will be described.

[0046] <First Modification> 7 shows a perspective view of a protrusion 50, which is a modification of the protrusion 30 (see FIG. 5) in the above embodiment, and the surrounding area on the base end side thereof. The protrusion 50 is formed in the shape of a four-pointed star when viewed from the opposite side in the direction of protrusion, and is formed in the shape of an isosceles triangle with the tip 50A as the vertex when viewed from the side. Such a protrusion 50 may be used in place of the protrusion 30 (see FIG. 5) in the above embodiment.

[0047] <Second Modification> FIG. 8 shows a perspective view of protrusion 52, which is another modification of protrusion 30 (see FIG. 5 ) in the above embodiment, and the surrounding area on the base end side thereof. FIG. 9 shows an enlarged cross-sectional view taken along line 9-9 in FIG. 8 . Protrusion 52 is formed in a double-cross shape with a tapering angle (the degree to which the width narrows toward the protruding tip) that changes in the middle of the protruding direction, and the tapering angle of approximately half of the protruding tip side is set smaller than the tapering angle of approximately half of the protruding base side. That is, protrusion 52 is formed in a four-pointed star shape when viewed from the opposite side of the protruding direction, and is formed in a shape such that the base of an isosceles triangle with tip 52A as the vertex is placed on the top side of an isosceles trapezoid in the cross-sectional view shown in FIG. 9 .

[0048] Such a protrusion 52 may be used in place of the protrusion 30 (see FIG. 5) of the above embodiment. With such a protrusion 52, the protrusion 52 can stably support the base end while making the tip end sufficiently sharp, so that it can more stably break through the breathable membrane 34 (see FIG. 3, etc.).

[0049] <Third Modification> Figure 10 shows a simplified front view of a base member 62 to which a ventilation membrane 64 is attached in a ventilation valve 60, which is a modified example of the ventilation valve 20 of the above embodiment. The base member 62 shown in Figure 10 has substantially the same basic configuration as the base member 22 of the above embodiment (see Figures 2 to 4), but has a square (broadly defined quadrangle) opening 62E that communicates with the inside of the housing 14 (see Figure 1). The ventilation membrane 64 is a flexible membrane that is square (broadly defined quadrangle) in front view, and covers the opening 62E formed in the base member 62 in a breathable manner.

[0050] In the vent valve 60, the shapes of the opening 62E and the vent membrane 64 differ from those of the opening 26E and the vent membrane 34 of the above embodiment (see FIG. 4 for both), but the other basic configuration is substantially the same as that of the vent valve 20 of the first embodiment (see FIGS. 2 to 4) except for differences associated with the difference in the shape of the opening 62E. Therefore, in FIG. 10, the protrusion 30 is denoted by the same reference numeral as in the above embodiment for convenience. The vent valve 60 described above also provides substantially the same actions and effects as the above embodiment.

[0051] (Supplementary explanation of the embodiment) In the above embodiment, the base member 22 shown in Figures 2 to 4 has a tapered portion 26D. However, as a modification of the above embodiment, the base member may have an inner peripheral surface that is connected to the outer peripheral side of the ventilation membrane (34) and extends with the same diameter, instead of the tapered portion 26D.

[0052] In addition, in the above embodiment, the protrusion 30 is provided on the base member 22. However, as a variation of the above embodiment, a configuration may be adopted in which the protrusion is supported on a part other than the base member 22, such as the most upstream part of the smoke exhaust hose (42) that is connected to the vent valve (20) and forms the smoke exhaust path (40), or the first cylindrical part (36A) of the cap (36).

[0053] Furthermore, in the above embodiment, the base member 22 is provided with a bridge portion 28 on which the protrusion portion 30 is provided, but as a variation of the above embodiment, the base member may be configured to have, instead of the bridge portion 28, a support arm, for example, one end of which is supported inside the gas flow path forming portion (22A) and which cantilevers the protrusion portion (30).

[0054] In the above embodiment, the bridging portion 28 is cross-shaped and the protrusion 30 is provided at the intersection 28A of the bridging portion 28, but it is also possible to adopt a configuration in which the bridging portion is configured to span only one direction (straight-line shaped) when the inside of the gas flow path forming portion (22A) is viewed in the gas discharge direction, and the protrusion 30 is provided on the bridging portion. In such a configuration, it is preferable that the bridging portion passes through the center of the flow path (22F) when the inside of the gas flow path forming portion (22A) is viewed in the gas discharge direction, and it is preferable that the protrusion 30 is provided at the center of the bridging portion in the span direction (in other words, the center of the flow path (22F)).

[0055] Furthermore, in the above embodiment, the battery pack 10 (see FIG. 1) has been described as being mounted on an autonomous vehicle (not shown) as an example, but the battery pack 10 can also be mounted on, for example, an electric vehicle that can be driven manually.

[0056] The above-described embodiment and the above-described modifications can be implemented in appropriate combinations.

[0057] The above describes one example of the present invention, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modified forms within the scope of the gist of the present invention. [Explanation of symbols]

[0058] 10 Battery pack 12 Battery stack (battery) 14. Case 20 Vent valve 22 Base material 22A Gas flow path forming part 22F flow channel 26D tapered section 26E opening 28 Bridge section 28A Intersection 30 Protrusion 30A tip 34 Breathable membrane 40 Smoke exhaust path 50 Protrusion 50A tip 52 Protrusion 52A tip 60 Vent valve 62 Base material 62E opening 64 Breathable membrane

Claims

1. A smoke exhaust structure for a battery pack having a battery housed in a housing, a vent valve that covers an opening communicating with the inside of the housing with a flexible ventilation membrane to allow ventilation and discharges gas discharged from the battery to the outside of the housing; a flue for guiding the gas discharged from the vent valve to a predetermined discharge location; a protrusion provided on the opposite side of the housing from the inside of the ventilation membrane, the protrusion configured to break through the ventilation membrane when the ventilation membrane expands by a predetermined amount due to an increase in internal pressure of the housing; and a base member having the opening formed therein and the ventilation membrane attached thereto, the base member being connected to the outer peripheral side of the ventilation membrane and having a tapered portion that is positioned downstream of the ventilation membrane in the gas discharge direction and that gradually reduces in diameter toward the downstream side in the gas discharge direction.

2. A smoke exhaust structure for a battery pack having a battery housed in a housing, a vent valve that covers an opening communicating with the inside of the housing with a flexible ventilation membrane to allow ventilation and discharges gas discharged from the battery to the outside of the housing; a flue for guiding the gas discharged from the vent valve to a predetermined discharge location; A protrusion provided on the opposite side of the housing from the inside of the breathable membrane with a gap therebetween, and arranged with a sharp tip facing the breathable membrane side; and a base member having the opening formed therein and the ventilation membrane attached thereto, the base member being connected to the outer peripheral side of the ventilation membrane and having a tapered portion that is positioned downstream of the ventilation membrane in the gas discharge direction and that gradually reduces in diameter toward the downstream side in the gas discharge direction.

3. A smoke exhaust structure for a battery pack having a battery housed in a housing, a vent valve that covers an opening communicating with the inside of the housing with a flexible ventilation membrane to allow ventilation and discharges gas discharged from the battery to the outside of the housing; a flue for guiding the gas discharged from the vent valve to a predetermined discharge location; a protrusion provided on the opposite side of the housing from the inside of the ventilation membrane, the protrusion configured to break through the ventilation membrane when the ventilation membrane expands by a predetermined amount due to an increase in internal pressure of the housing; and the ventilation valve includes a base member having the opening formed therein and having the ventilation membrane attached thereto; The base member is a gas flow path forming portion that forms a flow path of the gas; A bridge portion that is bridged inside the gas flow path forming portion and is arranged opposite to a part of the gas permeable membrane without blocking the gas flow path; and The protrusion is provided on the bridge portion, and is a smoke exhaust structure for a battery pack.

4. A smoke exhaust structure for a battery pack having a battery housed in a housing, comprising: a vent valve that covers an opening communicating with the inside of the housing with a flexible ventilation membrane to allow ventilation and discharges gas discharged from the battery to the outside of the housing; a flue for guiding the gas discharged from the vent valve to a predetermined discharge location; A protrusion provided on the opposite side of the housing from the inside of the breathable membrane with a gap therebetween, and arranged with a sharp tip facing the breathable membrane side; and the ventilation valve includes a base member having the opening formed therein and having the ventilation membrane attached thereto; The base member is a gas flow path forming portion that forms a flow path of the gas; A bridge portion that is bridged inside the gas flow path forming portion and is arranged opposite to a part of the gas permeable membrane without blocking the gas flow path; and The protrusion is provided on the bridge portion, and is a smoke exhaust structure for a battery pack.

5. The bridge portion has a cross shape that intersects at the center of the flow path when the inside of the gas flow path forming portion is viewed in the gas discharge direction, The smoke exhaust structure for a battery pack according to claim 3 or 4, wherein the protrusion is provided at an intersection of the bridge portion.

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