JP2018006061A - Battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery module capable of suppressing performance deterioration of a smoke exhaust duct due to gas, while avoiding increase in size of the battery module.SOLUTION: In a battery module including multiple battery cells 18 and a smoke exhaust duct 40 through which the gas discharged from the battery cells 18 flows, the battery cell 18 has a safety valve 24 for discharging the gas collected inside, when the internal pressure goes above a certain level, the smoke exhaust duct 40 has a protrusion 34 protruding from a face facing the safety valve 24 toward the safety valve 24, and becoming wider as it recedes from the safety valve 24, and the external size at the root of the protrusion 34 is equal to or larger than the external size of the safety valve 24.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a battery module including a plurality of battery cells and a smoke exhaust duct through which gas discharged from each battery cell flows.

  Conventionally, battery modules in which a plurality of battery cells, which are chargeable / dischargeable secondary batteries, are combined to form a module are widely known. It is known that a battery cell generates various gases inside the battery cell during charge / discharge or high temperature holding process. The battery cell is provided with a safety valve for releasing such gas to the outside of the battery cell. The battery module is also provided with a smoke exhaust duct that guides the gas released from the safety valve to the outside of the module. The smoke exhaust duct is a passage disposed near the safety valve and opened to the safety valve side. The gas released from the safety valve flows into the smoke exhaust duct through this opening.

JP 2013-098105 A

  Here, the gas released from the safety valve normally hits the surface of the smoke exhaust duct facing the safety valve. Since the gas to be released is high pressure and high temperature, when the gas hits, the facing surface deteriorates and the performance of the smoke exhaust duct may be deteriorated. Therefore, in order to prevent the performance of the smoke exhaust duct from degrading due to the gas, it is conceivable to enlarge the smoke exhaust duct and sufficiently separate the opposite surface of the smoke exhaust duct from the safety valve. With such a configuration, the gas decreases in temperature and flow velocity before hitting the opposing surface of the smoke exhaust duct, so that the deterioration of the opposing surface can be prevented. However, in this case, another problem of increasing the size of the smoke exhaust duct and, consequently, the battery module is caused.

  Patent Document 1 discloses that a rib that protrudes from a smoke exhaust cover (smoke exhaust duct) into a smoke exhaust gas flow path and directly hits a gas discharged from a safety valve is disclosed. With such a configuration, even if the distance between the facing surface of the flue gas and the safety valve is reduced, all or part of the heat (thermal energy) of the gas released from the safety valve can be absorbed by the rib. The deterioration of the facing surface of the smoke exhaust duct can be somewhat suppressed.

  However, in Patent Document 1, the rib is smaller than the safety valve. Therefore, most of the gas released from the safety valve directly collides with the facing surface of the smoke exhaust duct without contacting the rib. At this time, since the gas collides with the opposing surface as a collision jet having high thermal conductivity, the opposing surface of the smoke exhaust duct may be deteriorated by the heat of the gas. That is, even the technique of Patent Document 1 cannot sufficiently suppress the performance deterioration of the smoke exhaust duct caused by the gas.

  Therefore, an object of the present invention is to provide a battery module that can suppress a reduction in performance of a smoke exhaust duct caused by gas while avoiding an increase in size of the battery module.

  The battery module of the present invention includes a plurality of battery cells and a smoke exhaust duct through which the gas discharged from the battery cells flows, and the battery cell accumulates the gas when the internal pressure is a certain level or more. The smoke exhaust duct has a protrusion that protrudes from the surface facing the safety valve toward the safety valve and becomes wider as the distance from the safety valve increases, and the outer size of the base of the protrusion Is larger than the outer size of the safety valve.

  According to the present invention, since the gas released from the safety valve always hits the protrusion and changes into a laminar flow, the smoke exhaust duct, and hence the battery module, can be reduced in size, but the exhaust duct caused by the gas is deteriorated. The accompanying performance degradation can be suppressed.

It is a perspective view of the battery module which is embodiment of this invention. It is a perspective view of a battery cell. It is a front view of a resin frame. FIG. 4 is a schematic AA cross-sectional view of FIG. 3. It is an enlarged view around a duct piece. It is a figure which shows the flow of the gas when not having a protrusion.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of a battery module 10 according to an embodiment of the present invention. FIG. 2 is a perspective view of a battery cell 18 used in the battery module 10, and FIG. 3 is a front view of the resin frame 20. 4 is a schematic AA sectional view of FIG. 3, and FIG. 5 is an enlarged view around the duct piece 32. As shown in FIG.

  The battery module 10 is mounted on an electric vehicle, for example, an electric vehicle or a hybrid vehicle. The battery module 10 includes a battery stack 12, a pair of end plates 14 that sandwich the battery stack 12, and a restraining band 16 that connects the pair of end plates 14. The battery stack 12 is formed by alternately stacking a plurality of battery cells 18 and a plurality of resin frames 20 in the thickness direction.

  The battery cell 18 is a chargeable / dischargeable secondary battery, such as a nickel metal hydride battery or a lithium ion battery, and has a rectangular shape with a substantially rectangular shape when viewed from the front. From the upper end surface of the battery cell 18, a substantially cylindrical positive electrode terminal 22 p and negative electrode terminal 22 n protrude. The positive electrode terminal 22p and the negative electrode terminal 22n are arranged at an interval in the width direction.

  A safety valve 24 is provided in the center in the width direction of the upper end surface of the battery cell 18, that is, between the positive terminal 22p and the negative terminal 22n. The safety valve 24 is a valve that is opened when the internal pressure of the battery cell 18 exceeds a certain level, and discharges the gas accumulated in the battery cell 18 to the outside. That is, as described above, the battery cell 18 is a secondary battery that can be charged and discharged, but such a secondary battery generates various gases during charging and discharging or a high-temperature holding process. If such gas continues to accumulate in the case of the battery cell 18, the internal pressure of the battery cell 18 increases excessively. Therefore, when the internal pressure of the battery cell 18 exceeds a certain level, the safety valve 24 is opened and the gas is released to the outside.

  The safety valve 24 of the present embodiment is configured by partially thinning the case of the battery cell 18. That is, in the present embodiment, a thin-walled portion having a rounded rectangular shape elongated in the width direction and thinner than other portions is provided on the upper end surface of the case, and the thin-walled portion is used as the safety valve 24. When the internal pressure of the battery cell 18 increases, the thin and weak thin part (safety valve 24) is preferentially torn. And the gas in a case is discharge | released outside by the tearing of this thin part (safety valve 24). The configuration illustrated here is an example, and the safety valve 24 may have another configuration as long as the safety valve 24 is opened when the internal pressure becomes a certain level or more.

  The plurality of battery cells 18 are stacked in the thickness direction. At this time, the plurality of battery cells 18 are arranged with their orientations alternately changed so that the positive electrode terminals 22p and the negative electrode terminals 22n are alternately arranged in the stacking direction. That is, when a certain battery cell 18 is arranged so that the positive electrode terminal 22p is located on the right side, the next battery cell 18 is arranged so that the negative electrode terminal 22n is located on the right side. A plurality of battery cells 18 are electrically connected in series by sequentially connecting the positive electrode terminal 22p and the negative electrode terminal 22n adjacent in the stacking direction with a bus bar (not shown).

  A resin frame 20 is disposed between the battery cells 18. In other words, the battery stack 12 is formed by alternately stacking a plurality of battery cells 18 and a plurality of resin frames 20. The resin frame 20 is made of an insulating material, has a substantially flat base portion 26, a frame portion 28 that protrudes in the thickness direction from the periphery of the base portion 26, and a duct piece 32 provided at the upper end of the base portion 26. And a plurality of ribs 30 protruding from one surface of the base portion 26 (see FIG. 3).

  The frame portion 28 has a shape along the peripheral surface of the battery cell 18 and restricts movement of the battery cell 18 in the surface direction. The ribs 30 extend straight in the height direction of the resin frame 20, and a plurality of ribs 30 are provided at intervals in the width direction. When the battery cell 18 and the resin frame 20 are laminated, the front end surface of the rib 30 contacts the surface of the adjacent battery cell 18. Thereby, a passage surrounded by the side surface of the rib 30, the surface of the battery cell 18, and the base portion 26 is formed. This passage serves as a cooling flow path through which cooling air for cooling the battery cells 18 flows. Thick line arrows in FIG. 3 indicate the flow direction of the cooling air. As shown in FIG. 3, the cooling air supplied from the outside of the battery module 10 flows into the cooling channel from the lower side of the battery cell 18. Then, the cooling air flows through the cooling flow path while cooling the battery cell 18, and is finally discharged from the upper side of the battery cell 18 to the outside of the battery module 10.

  A duct piece 32 is provided at the upper end of the resin frame 20 and at the center in the width direction. The duct piece 32 is fixed to the upper end of the base portion 26 and has a substantially U shape that opens toward the upper end surface of the battery cell 18. In other words, the duct piece 32 includes a top surface 32a (opposing surface) facing the upper end surface of the battery cell 18, and a pair of side surfaces 32b extending in the height direction from both widthwise ends of the top surface 32a. (See FIG. 5). Further, the duct piece 32 protrudes in the thickness direction from the base portion 26 of the resin frame 20, and is in close contact with the duct piece 32 of another adjacent resin frame 20 (see FIG. 1). As the plurality of duct pieces 32 are in close contact with each other, a tunnel extending in the stacking direction is formed in the battery stack 12. This tunnel becomes a smoke exhaust duct 40 through which the gas released from the safety valve 24 flows.

  From the position facing the safety valve 24 on the top surface 32a of the duct piece 32, the protrusion 34 projects toward the safety valve 24 side. The protrusion 34 has a substantially elliptical cone shape that becomes wider as the distance from the safety valve 24 increases. However, the protrusion 34 is not a completely solid elliptical cone, but more accurately, the projection 34 has a substantially V-shaped shape in which the central portion in the width direction of the elliptical cone shape is cut off. In other words, the protrusion 34 has a shape in which an opening penetrating in the thickness direction is provided in the elliptical cone. When the protrusion 34 is provided, the flow area of the smoke exhaust duct 40 is reduced by that amount. However, if the protrusion 34 is provided with an opening as in the present embodiment, the opening is also used as a gas flow path. Since it functions, the fall of the flow-path area of the smoke exhaust duct 40 can be suppressed. In addition, by providing the opening, the amount of material of the protrusion 34 and thus the resin frame 20 can be reduced.

  The outer size of the base end (base) of the protrusion 34 is equal to or larger than the outer size of the safety valve 24. That is, as shown in FIG. 4, the width direction length D1 at the base end of the protrusion 34 is larger than the width direction length of the safety valve 24, and the thickness direction length D2 of the protrusion 34 is larger than the thickness direction length of the safety valve 24. It is getting bigger. In other words, the protrusion 34 has such a shape that the gas jetted right above the safety valve 24 always hits the protrusion 34 before reaching the top surface 32a. The protrusion 34 is provided in order to suppress the deterioration of the duct piece 32 while reducing the size of the duct piece 32. This will be described in detail later.

  A battery stack 12 including the battery cells 18 and the resin frame 20 is sandwiched between a pair of end plates 14. The end plate 14 is a plate material made of a metal such as aluminum. The pair of end plates 14 are connected by a restraining band 16. The restraint band 16 is a metal thin plate. The distance between the two end plates 14 is fixed by fastening the end plates 14 near both ends of the restraining band 16. The distance between the two end plates 14 at this time is approximately the same as or slightly smaller than the design length of the battery stack 12. Therefore, the battery stack 12 receives a compressive force from the end plate 14 by fastening the two end plates 14 to the restraining band 16. By receiving this compressive force, the mutual movement of the plurality of battery cells 18 and the resin frame 20 constituting the battery stack 12 is restricted and restrained. The shapes of the end plate 14 and the restraining band 16 shown in FIG. 1 are merely examples, and these configurations may be appropriately changed as long as the battery stack 12 can be compressed and sandwiched in the stacking direction.

  Next, the reason why the protrusion 34 is provided on the duct piece 32 in this embodiment will be described in detail. As described above, in the battery cell 18, gas is generated in the process of charging / discharging and holding at a high temperature, and the gas accumulates inside the case. When the amount of gas increases and the internal pressure of the battery cell 18 exceeds a certain level, the safety valve 24 is opened and the internal gas is released to the outside. The released gas flows through the smoke exhaust duct 40 and is released to the outside of the battery module 10.

  Here, when the duct piece 32 has no protrusion 34, the gas released from the battery cell 18 directly hits the top surface 32a of the duct piece 32 as shown in FIG. The gas immediately after being discharged from the battery cell 18 reaches a very high temperature, for example, around 400 degrees. When such high-temperature and high-pressure gas directly hits the top surface 32a of the duct piece 32, the top surface 32a may be deteriorated by heat or pressure, and the performance of the smoke exhaust duct 40 may be lowered. In particular, the gas discharged from the safety valve 24 and directly hitting the top surface 32a is a collision jet that collides with the top surface 32a substantially perpendicularly. Since the impinging jet has higher heat transfer efficiency than the laminar flow flowing in a direction substantially parallel to the wall surface, in the configuration of FIG. 5, the heat of the high-temperature gas is easily transmitted to the top surface 32a, and the top surface 32a and eventually the duct It was easy to cause deterioration of the piece 32. In order to prevent such deterioration of the duct piece 32, it is conceivable that the top surface 32 a of the duct piece 32 is sufficiently separated from the safety valve 24. That is, it is conceivable to increase the distance H from the top surface 32a to the safety valve 24. By increasing the distance H, the time until the gas moves to the top surface 32a becomes longer, and the pressure and temperature of the gas are reduced accordingly, and the deterioration of the duct piece 32 can be suppressed. However, when the distance H from the top surface 32a of the duct piece 32 to the safety valve 24 is increased, the height of the duct piece 32 and, consequently, the battery module 10 increases accordingly. Since the battery module 10 is mounted on an electric vehicle or the like, the installation space is limited, and it is not desirable to increase the height of the battery module 10.

  Therefore, in the present embodiment, the duct piece 32 is provided with a protrusion 34 that protrudes from the top surface 32a (opposing surface) toward the safety valve 24, and the external size of the base of the protrusion 34 is set to the external size of the safety valve 24. That's it. When such a protrusion 34 is provided, the gas released from the safety valve 24 always hits the protrusion 34. Thick line arrows in FIG. 5 indicate gas flows. As shown in FIG. 5, the gas jetted straight upward from the safety valve 24 is dispersed when it hits the protrusion 34, and flows obliquely upward along the outer surface of the protrusion 34. By colliding with the protrusion 34 in this manner, the gas changes from a collision jet to a laminar flow that flows along the wall surface. Since the laminar flow has a lower heat transfer efficiency than the impinging jet, the heat of the gas is less likely to be transmitted to the top surface 32a. As a result, even if the distance H between the top surface 32a and the safety valve 24 is reduced, deterioration of the top surface 32a, and hence the duct piece 32, is suppressed. Reduction (low profile) is possible. Further, when the protrusion 34 is provided, the protrusion 34 with which the gas first collides preferentially melts and deteriorates. Since heat energy is consumed for melting / deteriorating the projections 34, thermal deterioration of the outer portion forming the smoke exhaust duct 40 such as the top surface 32a and the side surface 32b is effectively prevented. In other words, since the projecting body 34 exhibits a sacrificial anticorrosive action, the performance deterioration of the smoke exhaust duct 40 can be more reliably suppressed, and the battery module 10 can be further downsized.

  In the present embodiment, the outer size of the base of the protrusion 34 is set to be equal to or larger than the outer size of the safety valve 24. As a result, all the gas released from the safety valve 24 collides with the protrusion 34. In other words, according to the present embodiment, no gas that collides with the top surface 32a as a collision jet with high heat transfer efficiency is generated. As a result, the deterioration of the duct piece 32 and consequently the performance reduction of the smoke exhaust duct 40 can be prevented more reliably, and the battery module 10 can be further downsized.

  The configuration described so far is merely an example, and the protrusion 34 becomes wider as it moves away from the safety valve 24. If the outer size of the base of the protrusion 34 is equal to or larger than the outer size of the safety valve 24, the other configurations are as follows. It may be changed as appropriate. For example, in the present embodiment, the protrusion 34 has a substantially elliptical cone shape with an opening in the center. However, the protrusion 34 is wide enough to move away from the safety valve 24, and the colliding gas can be changed into a laminar flow. Any other shape may be used. Therefore, the protrusion 34 may have, for example, a conical shape, a pyramid shape, a hemispherical shape, or the like. Further, the protrusion 34 may have a semi-cylindrical shape extending in the entire thickness direction of each duct piece 32, a triangular prism shape, or the like. Further, the protrusion 34 may have an opening, or may have a completely solid configuration without an opening.

  Moreover, in this embodiment, the duct piece 32 integrally formed with the resin frame 20 is connected to configure the smoke exhaust duct 40. However, the smoke exhaust duct 40 is configured separately from the resin frame 20. Also good. Further, at that time, one smoke exhaust duct 40 may be configured by combining a plurality of duct pieces 32, or one smoke exhaust duct 40 may be configured by a single member. In the present embodiment, the safety valve 24 is provided on the upper surface of the rectangular battery cell 18, but the position, shape, and the like of the safety valve 24 may be changed as appropriate. For example, the safety valve 24 may be provided on the bottom surface of the square battery cell 18. In this case, the smoke exhaust duct 40 is disposed on the lower side of the battery stack 12.

  In any case, by providing a projection 34 at the position facing the safety valve 24 in the smoke exhausting duct 40, the base outer size is equal to or larger than the outer size of the safety valve 24 and becomes wider as the distance from the safety valve 24 increases. While reducing the size of the smoke duct 40, it is possible to effectively prevent the deterioration of the smoke exhaust duct 40, and hence the performance degradation.

DESCRIPTION OF SYMBOLS 10 Battery module, 12 Battery stack, 14 End plate, 16 Restraint band, 18 Battery cell, 20 Resin frame, 22n Negative electrode terminal, 22p Positive electrode terminal, 24 Safety valve, 26 Base part, 28 Frame part, 30 Rib, 32 Duct piece, 32a Top surface, 32b Side surface, 34 Projection body, 40 Smoke exhaust duct.

Claims (1)

A plurality of battery cells;
A smoke exhaust duct through which gas discharged from the battery cell flows;
With
The battery cell has a safety valve that releases the gas accumulated inside when the internal pressure is a certain level or more,
The smoke exhaust duct protrudes from the surface facing the safety valve toward the safety valve, and has a protrusion that becomes wider as the distance from the safety valve increases.
The external size of the base of the protrusion is not less than the external size of the safety valve.
A battery module.

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