Pressure relief valve for battery pack

Abstract

Provided is a pressure relief valve for a battery pack configured to be fitted to an opening portion formed in a battery pack case of a battery pack. The pressure relief valve for the battery pack includes a housing having a discharge hole and a valve mechanism that opens and closes the discharge hole, the discharge hole being in communication with the opening portion when the pressure relief valve for the battery pack is fitted to the opening portion; and a cover fitted to the housing, a passage for discharging gas discharged from the discharge hole being formed between the cover and the housing. The valve mechanism includes a valve member configured to close the discharge hole, and a force application portion configured to apply a force to the valve member at a closed position that is a position at which the valve member closes the discharge hole.

Description

This application is a divisional application of application No. 202080037971.7. Technical Field

[0001] This disclosure relates to pressure relief valves for battery packs. Background Technology

[0002] For example, battery packs used in electric vehicles, hybrid vehicles, etc., house multiple batteries within a battery pack casing. Each battery is equipped with a pressure adjustment mechanism to release gas and maintain the internal pressure within a predetermined range. Furthermore, to prevent excessive pressure rise due to gas release from each battery, an opening is provided in the battery pack casing, and a pressure relief valve is provided in this opening that opens when the pressure difference between the inside and outside of the battery pack casing reaches a predetermined pressure difference (see, for example, Patent Document 1).

[0003] The pressure relief valve described in the aforementioned literature has a diaphragm-like sheet member and a reinforcing plate with multiple small holes forming through it. The sheet member and the reinforcing plate overlap to cover the opening of the battery pack casing. Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2017-73195 Summary of the Invention The problem that the invention aims to solve

[0005] Assuming that the amount of gas discharged from the battery pack casing increases with the increase in the number of batteries inside the battery pack casing, it is desirable to increase the inner diameter of the opening formed in the battery pack casing. However, in the pressure relief valve described above, when the plate member is enlarged according to the enlarged inner diameter opening, the sealing performance may decrease due to the increased deflection of the plate member.

[0006] The purpose of this disclosure is to provide a pressure relief valve for a battery pack that ensures high sealing performance regardless of the inner diameter of the opening formed in the battery pack. Solution for solving the problem

[0007] According to one aspect of this disclosure, a pressure relief valve for a battery pack is provided, configured to be fitted onto an opening formed in the battery pack casing of a battery pack. The pressure relief valve includes: a housing having a discharge port and a valve mechanism configured to open and close the discharge port, wherein the discharge port communicates with the opening when the pressure relief valve is fitted onto the opening; and a cover fitted onto the housing, forming a passage between the cover and the housing for discharging gas from the discharge port. The valve mechanism includes: a valve member configured to close the discharge port; and a force-applying portion that applies force to the valve member in a closed position, where the valve member closes the discharge port. Attached Figure Description

[0008] Figure 1 This is a perspective view showing the overall structure of a pressure relief valve for a battery pack, which is mounted on the battery pack housing according to one embodiment. Figure 2 yes Figure 1 An exploded perspective view of the pressure relief valve in the embodiment. Figure 3 yes Figure 1 A cross-sectional view of the pressure relief valve in the embodiment. Figure 4 yes Figure 1 A cross-sectional view of the valve component of the pressure relief valve according to the embodiment. Figure 5 yes Figure 1 A top view of the pressure relief valve in the open state in the embodiment. Figure 6 yes Figure 1 A cross-sectional view of the pressure relief valve in the open state in the embodiment. Detailed Implementation

[0009] The following describes a pressure relief valve for a battery pack according to one embodiment. like Figure 1 As shown, a pressure relief valve (hereinafter referred to as pressure relief valve 10) is mounted on the battery pack housing 12 of the battery pack 11. The battery pack 11 contains multiple batteries (not shown) within the battery pack housing 12. Each battery contains battery components such as a positive electrode, a negative electrode, and an electrolyte. The battery housing is equipped with a pressure regulating mechanism, such as a valve device, to release internal gas in case of excessive pressure rise. The gas released from the battery housing through the pressure regulating mechanism fills the battery pack housing 12. Furthermore, an opening 13 is formed in the battery pack housing 12 for releasing gas from within the battery pack housing 12.

[0010] The pressure relief valve 10 opens and closes the opening 13 of the battery pack housing 12. The pressure relief valve 10 releases gas from the battery pack housing 12 by opening when the pressure inside the battery pack housing 12 at atmospheric pressure reaches a set upper limit pressure. The pressure relief valve 10 is fastened to the battery pack housing 12 by bolts or other fastening components 14.

[0011] like Figure 2 As shown, the pressure relief valve 10 includes a housing 20 and a cover 21. The housing 20 has a housing body 22 that is circular when viewed from the cover 21. A discharge port 23 communicating with an opening 13 of the battery pack housing 12 is formed in the housing body 22 (see reference). Figure 3 ).

[0012] Additionally, a valve mechanism 25 for opening and closing the discharge port 23 is provided in the housing 20. The valve mechanism 25 has a valve seat 26 surrounding the discharge port 23 and a flap-type valve member 27. The valve member 27 has a disc-shaped shape. Furthermore, a pair of arms 28 extending radially outward from the center of the valve member 27 are formed on the surface of the valve member 27. A shaft hole (not shown) is formed through the base end of the arm 28, and the two ends of a rotating shaft 29 are respectively inserted into the shaft hole. The two ends of the rotating shaft 29 are rotatably supported by shaft support portions 30 formed in the housing 20.

[0013] Additionally, a force-applying part 31 is supported on the housing body 22. The force-applying part 31 is a double torsion spring connected by a pair of torsion coil springs. The force-applying part 31 has a protrusion 32 protruding from between the pair of torsion coil springs. The top end of the protrusion 32 is fixed to the center of the valve member 27, thereby applying the force of the force-applying part 31 to the valve member 27.

[0014] When the pressure inside the battery pack casing 12 reaches the set upper limit pressure, the valve member 27 rotates around the base end of the arm 28 supported on the shaft support 30, resisting the force applied by the force application part 31. As a result, a part of the valve member 27 leaves the valve seat 26, and the gas inside the battery pack casing 12 is discharged from the discharge port 23.

[0015] Additionally, a pair of fastening portions 34 are provided on the housing 20. The housing 20 has a housing body 22 and a pair of fastening portions 34, which are connected to the housing body 22 and located on the outside of the housing body 22. The pair of fastening portions 34 are positioned symmetrically about the radial center of the housing body 22. A fastening hole 35 for inserting a fastening member 14 and a connecting hole 36 serving as a discharge channel are formed through the fastening portions 34. The fastening hole 35 accommodates the fastening member 14 that fixes the housing 20 to the battery pack housing 12. The connecting hole 36 is closer to the housing body 22 than the fastening hole 35. That is, the connecting hole 36 is located between the housing body 22 and the fastening hole 35. In addition, the cover 21 covers the connecting hole 36. Furthermore, a peripheral wall portion 49 surrounding the valve mechanism 25 is provided on the housing body 22, and a notch portion 49A is provided in the peripheral wall portion 49 at a position corresponding to the fastening portion 34.

[0016] Additionally, the housing body 22 has a locking portion 37 that is pressed into a hole 21B formed in the cover 21. By pressing the locking portion 37 into the hole 21B of the cover 21, the cover 21 is positioned relative to the housing 20 in its circumferential direction.

[0017] like Figure 3 As shown, the cover 21 has a storage space 21A, which stores the portion of the housing 20 excluding the fastening part 34. Figure 3 As shown, the cover 21 has a lower end that opens in the direction opposite to the Z direction. Furthermore, the outer diameter of the housing body 22, excluding the fastening part 34, is smaller than the inner diameter of the cover 21. Therefore, a gap is provided between the cover 21 and the housing 20, which forms a gas passage 40. The cover 21 has a lower end 21C that inserts into the connecting hole 36. Additionally, a gap 41 is provided between the lower end 21C of the cover 21 and the surface of the battery pack housing 12, through which gas that has passed through the passage 40 is discharged to the outside of the pressure relief valve 10. Alternatively, it can be said that the gap 41 is located between the fastening part 34 and the battery pack housing 12.

[0018] Additionally, the housing 20 has a connecting portion 38, which is inserted into the opening 13 of the battery pack housing 12. The connecting portion 38 has a cylindrical shape and a discharge hole 23 on its inner side. A first sealing member 42 and a second sealing member 43 are provided on the outer peripheral surface of the connecting portion 38. The first sealing member 42 has a circular cross-section and is sandwiched between the inner peripheral surface of the opening 13 of the battery pack housing 12 and the housing 20. The second sealing member 43 abuts against the surface of the battery pack housing 12 when the pressure relief valve 10 is assembled with the battery pack housing 12.

[0019] The valve component 27 is formed by assembling a first valve core 44 and a second valve core 45. The first valve core 44 and the second valve core 45 are connected by engaging the fitting portion 46 of the first valve core 44 with the fitted portion 47 of the second valve core 45. An annular third sealing member 50 is sandwiched between the first valve core 44 and the second valve core 45.

[0020] Reference Figure 4 The third sealing member 50 is described in detail. The inner circumferential end 51 of the third sealing member 50 is received within the groove 48 of the second valve core 45. A pair of lips 52 are provided at the end 51. The lips 52 are pressed against the second valve core 45. The outer circumferential end 53 of the third sealing member 50 is sandwiched between the protrusion 26A of the valve seat 26 and the second valve core 45 when the pressure relief valve 10 is closed. Additionally, an auxiliary lip 54 is provided at the end 53 of the third sealing member 50. The auxiliary lip 54 extends outward beyond the second valve core 45, sealing the space between the valve member 27 and the housing 20, thereby preventing dust from entering the valve member 27.

[0021] Furthermore, an annular rib 55, serving as a protrusion, is formed on the edge of the second valve core 45. The annular rib 55 is positioned radially outward from the protrusion 26A in the discharge port 23. Additionally, as... Figure 4 As shown, the annular rib 55 protrudes in the direction opposite to the Z direction. Figure 4 As shown, the annular rib 55 abuts against the third sealing member 50 from the side opposite to the protrusion 26A projecting in the Z direction, pressing the third sealing member 50. Therefore, when the valve member 27 is in the closed position, the third sealing member 50 is subjected to pressing pressure at two locations between the valve seat 26 and the second valve core 45. Consequently, the pressing pressure on the third sealing member 50 is distributed, thereby reducing the surface pressure caused by the abutment between the third sealing member 50 and the valve seat 26.

[0022] Reference Figure 5 and Figure 6 The function of pressure relief valve 10 is explained. Figure 5 The cover 21 is shown in dashed lines. A channel 40 is formed between the outer peripheral surface of the housing 20 (excluding the fastener 34) and the inner peripheral surface of the cover 21. Therefore, when the internal pressure of the battery pack housing 12 reaches a predetermined upper limit pressure, causing the valve member 27 to open, the gas inside the battery pack housing 12... Figure 5 As indicated by the middle arrow, the gas diffuses radially from the discharge hole 23 and is discharged to the outside through the channel 40. Additionally, gas flowing toward the fastening part 34 flows into the connecting hole 36 through the notch 49A.

[0023] like Figure 6As shown, the gas that has passed through the connecting hole 36 passes through the gap 41 between the fastening part 34 and the battery pack housing 12 and is discharged to the outside of the pressure relief valve 10. The valve mechanism 25 opens the valve, thereby reducing the internal pressure of the battery pack housing 12. When the pressure is lower than the specified upper limit pressure, the force of the force application part 31 causes the valve member 27 to abut against the valve seat 26.

[0024] As described above, the following effects are obtained according to the above embodiments. (1) In the above embodiment, the pressure relief valve 10 applies force to the valve member 27 towards the closed position using the force-applying part 31. Therefore, in the above embodiment, compared with the valve device that uses a diaphragm valve member to close the opening 13, the sealing performance of the valve member 27 when it is in the closed position can be improved. In addition, since the cover 21 is provided on the housing 20, it is possible to prevent dust from entering the battery pack housing 12 when the valve mechanism 25 is open. Furthermore, in the pressure relief valve 10 with the cover 21 provided on the housing 20, a gas discharge channel 40 is formed between the inner peripheral surface of the cover 21 and the outer peripheral surface of the housing body 22. Therefore, the ventilation resistance in the channel 40 from the opening 13 of the battery pack housing 12 to the outside of the pressure relief valve 10 can be reduced. Therefore, by increasing the inner diameter of the opening 13 of the battery pack housing 12, even if the maximum flow rate of the gas discharged from the opening 13 increases, the gas can be smoothly discharged to the outside.

[0025] (2) In the above embodiment, in addition to the channel 40 provided between the housing 20 and the cover 21, a gas discharge port 36 is also provided in the fastening part 34. Therefore, in the above embodiment, the increase in ventilation resistance caused by the fastening part 34 can be suppressed.

[0026] (3) In the above embodiment, the gas that has passed through the connecting hole 36 further passes through the gap 41 between the fastening part 34 and the battery pack casing 12 and is discharged to the outside. Therefore, the ventilation resistance of the gas discharged from the discharge hole 23 can be reduced.

[0027] (4) In the above embodiment, when the valve member 27 is in the closed position, the third sealing member 50 abuts against both the valve seat 26 and the annular rib 55, the annular rib 55 being positioned further away from the discharge hole 23 than the valve seat 26. Therefore, the surface pressure generated by the abutment of the third sealing member 50 and the valve seat 26 can be reduced. Therefore, even if the valve member 27 is in the closed position for a long time, the adhesion of the third sealing member 50 to the valve seat 26 and the like can be suppressed.

[0028] (5) In the above embodiment, a gas passage 40 is formed throughout the entire circumference of the housing body 22 except for the fastening part 34, so that the ventilation resistance when the gas passes through the passage 40 can be reduced.

[0029] (Other implementation methods) This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined and implemented within the scope of technical inconsistency.

[0030] In the above embodiment, the channel 40 is formed by the outer periphery of the housing body 22 (excluding the fastening part 34) and the cover 21. However, the channel 40 may also correspond to a region smaller than the outer periphery of the housing body 22 (excluding the fastening part 34). Alternatively, if the fastening part 34 is provided on a portion other than the outer periphery of the housing body 22, the channel 40 may also be formed by the outer periphery of the housing body 22 and the cover 21.

[0031] In the above embodiment, the valve member 27 includes an annular rib 55 that presses against the end 53 of the third sealing member 50. Alternatively, the annular rib 55 may be omitted if the adhesion of the third sealing member 50 to the valve seat 26 or the like can be suppressed by adjusting the force of the force-applying part 31. Alternatively, the annular rib 55 may be replaced, or at least one of the third sealing member 50, the valve member 27, or the valve seat 26 may be subjected to a non-adhesive treatment to suppress the adhesion of the third sealing member 50 to the valve seat 26 or the like.

[0032] In the above embodiment, the lower end of the cover 21 assembled on the housing 20 is moved away from the battery pack housing 12, allowing the gas that has passed through the connecting hole 36 to be discharged from the lower end of the cover 21. Alternatively, or based on this, a gas passage hole may be formed in the housing 20 or the cover 21.

[0033] In the above embodiment, the discharge channel formed in the fastening part 34 corresponds to the communication hole 36 penetrating the fastening part 34. Alternatively, the discharge channel can be formed using the gap formed between the fastening part 34 and the cover 21.

[0034] In the above embodiment, a connecting hole 36 is provided in the fastening part 34. Alternatively, the connecting hole 36 can be omitted from the fastening part 34. Even in this case, since the passage is formed by the channel 40 provided in the part other than the fastening part 34, the ventilation resistance when gas discharged from the battery pack casing 12 passes through can be reduced.

[0035] In the above embodiment, the valve component 27 is composed of the first valve core 44 and the second valve core 45, but it can also be composed of a single component, and the third sealing component 50 is assembled on the valve component 27.

Claims

1. A pressure relief valve for a battery pack, configured to be fitted into an opening formed in the battery pack casing, characterized in that, The pressure relief valve for the battery pack includes: A housing having a discharge port and a valve mechanism configured to open and close the discharge port, wherein the discharge port communicates with the opening when the battery pack pressure relief valve is assembled to the opening; and A cover, which is fitted onto the housing, and forms a channel between the cover and the housing for the discharge of gas from the discharge port. The valve mechanism includes: a cap-type valve member configured to close the discharge port; and a force-applying part that applies force to the valve member in a closed position, which is the position where the valve member closes the discharge port. The housing has: Shell body; A fastening part protrudes to the outer periphery of the housing body, and a fastening member is provided in the fastening part to fix the housing to the battery pack outer shell; and A peripheral wall portion, which is disposed on the housing body, surrounds the valve mechanism, and a notch portion is provided in the peripheral wall portion at a location corresponding to the fastening portion. The fastening part has a fastening hole configured to accommodate the fastening member that secures the housing to the battery pack housing; And a connecting hole serving as a discharge channel for the gas discharged from the discharge port, the connecting hole being located between the housing body and the fastening hole. When the pressure inside the battery pack casing reaches the set upper limit pressure, the valve member counteracts the force of the force-applying part and rotates around the rotation axis of the shaft support portion formed on the casing, and the gas discharged from the discharge hole and flowing toward the fastening part flows into the communication hole through the notch portion.

2. The pressure relief valve for a battery pack according to claim 1, wherein, When the pressure relief valve of the battery pack is assembled to the opening, a gap is formed between the fastener and the battery pack housing, thereby allowing gas that has passed through the connecting hole to be discharged to the outside through the gap.

3. The pressure relief valve for a battery pack according to claim 1, wherein, The pressure relief valve for the battery pack also includes a sealing member that abuts against a valve seat disposed around the discharge port when the valve member is in the closed position. The valve member has a protrusion that presses against the top end of the sealing member, the protrusion being positioned further away from the discharge port than the valve seat.

4. The pressure relief valve for a battery pack according to claim 1, wherein, The cover covers the connecting hole.

5. The pressure relief valve for a battery pack according to claim 1, wherein, The cover has a lower end that inserts into the communicating hole. When the pressure relief valve of the battery pack is assembled to the opening, a gap is formed between the lower end of the cover and the battery pack housing, thereby allowing gas that has passed through the connecting hole to be discharged to the outside through the gap.

6. The pressure relief valve for a battery pack according to any one of claims 1 to 5, wherein, The connecting hole is located in the direction in which the rotation axis extends, with the radial center of the housing body as a reference.

7. The pressure relief valve for a battery pack according to any one of claims 1 to 5, wherein, The force-applying part is located radially outward, with the radial center of the housing body as the reference.

8. The pressure relief valve for a battery pack according to any one of claims 1 to 5, wherein, The rotation axis is located radially outward with respect to the radial center of the housing body.

9. The pressure relief valve for a battery pack according to any one of claims 1 to 5, wherein, The valve member has a pair of arms extending radially outward from the central portion of the valve member. A shaft hole is formed at the base end of the pair of arms. Both ends of the rotating shaft are inserted into the shaft hole.

10. The pressure relief valve for a battery pack according to any one of claims 1 to 5, wherein, The force-applying part is a double torsion spring formed by a pair of torsion coil springs connected together. The force-applying part has a protrusion extending from between the pair of torsion coil springs. The top end of the protrusion is fixed to the center of the valve component.

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