Battery pack

Abstract

To provide a battery pack that can be made compact while ensuring strength.SOLUTION: A battery pack 1, which houses a plurality of battery modules 3, each of which has a plurality of stacked battery cells, includes a lower case 10 that covers the lower portions of the plurality of battery modules 3. The lower case 10 is provided with a cross member 16 that stands upward from a bottom plate portion 11 and extends continuously in a left-right direction from a left wall portion 14 to a right wall portion 15 in a battery module housing portion P, and a cover frame 17 that extends in the left-right direction and covers at least a part of an upper portion of the cross member 16. The cross member 16 is made of solid metal and extends in the left-right direction from both left and right ends toward the left-right center such that the position of the upper end becomes lower, and the cover frame 17 is formed of a metal plate and fixed to the cross member 16.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a battery pack to be mounted on a vehicle or the like. [Background technology]

[0002] In recent years, research and development has been conducted on secondary batteries that contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. In particular, with regard to vehicles, the recent rise in awareness of global environmental protection has led to rapid progress in the electrification of drive sources, such as hybrid vehicles and electric vehicles. Battery packs installed in electric vehicles include a battery case that houses a battery module (see, for example, Patent Document 1). To ensure strength, the battery case is provided with a cross member that extends in the left-right direction. The battery case and the cross member are formed, for example, from iron. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-097816 Summary of the Invention [Problem to be solved by the invention]

[0004] To reduce weight, aluminum die-casting is being used instead of steel for battery cases and cross members, but to achieve the same strength as steel with aluminum die-casting, the width of the cross member needs to be increased. However, increasing the width of the cross member consumes space within the battery case, which results in an increase in the overall length of the battery pack.

[0005] The present invention provides a battery pack that can be made smaller while maintaining strength, which in turn contributes to improved energy efficiency. [Means for solving the problem]

[0006] The present invention provides A battery pack containing a plurality of battery modules, each of which has a plurality of stacked battery cells, The battery pack a lower case covering lower portions of the plurality of battery modules; an upper cover that covers an upper portion of the plurality of battery modules; The lower case includes: a bottom plate portion covering lower portions of the plurality of battery modules; a front wall portion that stands upward and extends in the left-right direction at a front portion of the bottom plate portion; a rear wall portion that stands upward and extends in the left-right direction at a rear portion of the bottom plate portion; a left wall portion standing upward and extending in the front-rear direction at a left portion of the bottom plate portion; a right wall portion that stands upward and extends in the front-rear direction at a right portion of the bottom plate portion, the plurality of battery modules are arranged in a battery module housing portion surrounded by the bottom plate portion, the front wall portion, the rear wall portion, the left wall portion, and the right wall portion, The lower case includes: a cross member that stands upward from the bottom plate portion in the battery module accommodating portion and extends continuously in the left-right direction from the left wall portion to the right wall portion; a cover frame extending in the left-right direction and covering at least a portion of the upper portion of the cross member, The cross member is a solid aluminum The upper end of the panel extends laterally from both the left and right ends toward the center in the left-right direction so that the position of the upper end becomes lower. The cover frame is iron and fixed to the cross member. It is a battery pack. The present invention also provides A battery pack containing a plurality of battery modules, each of which has a plurality of stacked battery cells, The battery pack a lower case covering lower portions of the plurality of battery modules; an upper cover that covers an upper portion of the plurality of battery modules; The lower case includes: a bottom plate portion covering lower portions of the plurality of battery modules; a front wall portion that stands upward and extends in the left-right direction at a front portion of the bottom plate portion; a rear wall portion that stands upward and extends in the left-right direction at a rear portion of the bottom plate portion; a left wall portion standing upward and extending in the front-rear direction at a left portion of the bottom plate portion; a right wall portion that stands upward and extends in the front-rear direction at a right portion of the bottom plate portion, the plurality of battery modules are arranged in a battery module housing portion surrounded by the bottom plate portion, the front wall portion, the rear wall portion, the left wall portion, and the right wall portion, The lower case includes: a cross member that stands upward from the bottom plate portion in the battery module accommodating portion and extends continuously in the left-right direction from the left wall portion to the right wall portion; a cover frame extending in the left-right direction and covering at least a portion of the upper portion of the cross member, The cross member is made of a solid first metal and extends in the left-right direction from both left and right ends toward the left-right center such that the position of the upper end becomes lower, The cover frame is formed of a second metal plate and fixed to the cross member, The first metal is lighter than the second metal, and the second metal is stronger than the first metal. It is a battery pack. [Effects of the Invention]

[0007] According to the present invention, the load during a collision can be absorbed by both the solid metal cross member attached to the lower case and the cover frame formed from a metal plate material. This allows the front-to-rear width of the cross member to be reduced, thereby reducing the space required for the cross member in the battery pack and enabling the battery pack to be made more compact. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a battery pack according to an embodiment of the present invention; [Figure 2] 2 is a perspective view of the battery pack of FIG. 1 with the top cover removed. [Figure 3] FIG. 2 is a perspective view of a lower case of the battery pack of FIG. 1. [Figure 4] 2 is an enlarged cross-sectional view of a main portion of a cross member and a cover frame in the battery pack of FIG. 1. FIG. [Figure 5]2 is a perspective view showing the flow of high-temperature gas generated in a battery module in the battery pack of FIG. 1. FIG. [Figure 6] 2 is an enlarged view of a pressure release valve and a temperature sensor in the battery pack of FIG. 1. [Figure 7] FIG. 2 is an enlarged cross-sectional view (reference diagram) of a key part of the battery pack of FIG. 1, showing the flow of high-temperature gas generated in the battery module when the upper end of the cover frame extends in the left-right direction at a height lower than the upper end of the battery module. [Figure 8] This is a perspective view (reference diagram) showing the flow of high-temperature gas generated in the battery module when the upper end of the cover frame extends in the left-right direction at a height lower than the upper end of the battery module in the battery pack of Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a battery pack of the present invention will be described with reference to the accompanying drawings. The drawings should be viewed in the direction indicated by the reference numerals.

[0010] 1 and 2, a battery pack 1 according to one embodiment of the present invention is a flat, rectangular-shaped member having a predetermined thickness when viewed from above. The battery pack 1 is mounted on the floor or the like of an electric vehicle to drive an electrically powered drive source. The electrically powered drive source is, for example, a vehicle drive motor.

[0011] The battery pack 1 houses a plurality of battery modules 3, each of which has a plurality of stacked battery cells. The battery pack 1 includes a lower case 10 that covers the lower portions of the plurality of battery modules 3, and an upper cover 20 that covers the upper portions of the plurality of battery modules 3.

[0012] For the sake of simplicity and clarity of explanation, the direction in which a surface on which a pressure release valve 30 (described later) is provided is defined as the front-rear direction, and the up-down, left-right, and right-left directions are described according to the directions as seen from the battery pack 1. In the drawings, the front of the battery pack 1 is indicated as Fr, the rear as Rr, the left side as L, the right side as R, the top as U, and the bottom as D. Note that the up-down, front-rear, and left-right directions shown in this specification are unrelated to the orientation of a product in which the battery pack 1 is mounted. In other words, when the battery pack 1 is mounted in a vehicle, the up-down, front-rear, and left-right directions shown in this specification may or may not match the up-down, front-rear, and left-right directions as seen from the vehicle.

[0013] As shown in FIG. 3 , the lower case 10 has a bottom plate 11, a front wall 12, a rear wall 13, a left wall 14, and a right wall 15. The bottom plate 11 is a flat plate-shaped portion corresponding to the bottom of the lower case 10 and covers the lower portions of the multiple battery modules 3. The front wall 12 is a wall-shaped portion that stands upward and extends in the left-right direction at the front of the bottom plate 11. The rear wall 13 is a wall-shaped portion that stands upward and extends in the left-right direction at the rear of the bottom plate 11. The left wall 14 is a wall-shaped portion that stands upward and extends in the front-rear direction at the left part of the bottom plate 11. The right wall 15 is a wall-shaped portion that stands upward and extends in the front-rear direction at the right part of the bottom plate 11.

[0014] The battery module accommodating section P is defined by a space surrounded by the bottom plate section 11, the front wall section 12, the rear wall section 13, the left wall section 14, and the right wall section 15. A plurality of battery modules 3 are arranged in the battery module accommodating section P. In this embodiment, the battery modules 3 are arranged in two rows in the left-right direction in the battery module accommodating section P, lined up in the front-rear direction, with seven battery modules in the right row and six battery modules in the left row.

[0015] As shown in Fig. 3, the lower case 10 is provided with a cross member 16 in the battery module housing section P that stands upward from the bottom plate section 11 and extends continuously in the left-right direction from the left wall section 14 to the right wall section 15. Furthermore, the lower case 10 is provided with a cover frame 17 (see Fig. 4) that covers at least a portion of the upper part of the cross member 16 and extends in the left-right direction.

[0016] The cross member 16 is made of solid metal and extends in the left-right direction from both left and right ends so that the position of the upper end becomes lower toward the center in the left-right direction. In this embodiment, the cross member 16 has approximately the same height as the left wall portion 14 and the right wall portion 15 at the portions where the cross member 16 contacts the left wall portion 14 and the right wall portion 15, and the height decreases linearly from each of the left wall portion 14 and the right wall portion 15 toward the center in the left-right direction.

[0017] The cover frame 17 is formed from a metal plate and is fixed to the cross member 16. In this embodiment, the cover frame 17 has a substantially U-shaped cross section when viewed from the left and right, and covers the upper end and side surfaces of the cross member 16.

[0018] According to the battery pack 1 of this embodiment, the load during a collision can be received by both the solid metal cross member 16 provided in the lower case 10 and the cover frame 17 formed from a metal plate. This allows the width of the cross member 16 in the front-to-rear direction to be reduced, thereby reducing the space required for the cross member 16 in the battery pack 1 and enabling the battery pack 1 to be made more compact.

[0019] Furthermore, by having the load during a collision received by both the cross member 16 and the cover frame 17, the load received by the cross member 16 during a collision can be reduced, allowing the height of the central region of the cross member 16 to be lowered. This reduces the weight of the solid cross member 16, thereby enabling the weight of the battery pack 1 to be reduced.

[0020] The bottom plate portion 11, the front wall portion 12, the rear wall portion 13, the left wall portion 14, the right wall portion 15, the cross member 16, and the cover frame 17 may be formed of any metal material. In this embodiment, the bottom plate portion 11, the front wall portion 12, the rear wall portion 13, the left wall portion 14, the right wall portion 15, and the cross member 16 are integrally formed from aluminum, and the cover frame 17 is made of iron.

[0021] The bottom plate 11, front wall 12, rear wall 13, left wall 14, right wall 15, and cross member 16 are all made of aluminum and integrally molded, which allows the load during a collision to be distributed between the cross member 16 and the lower case 10. Furthermore, the cover frame 17 is made of iron, which improves heat resistance and makes it easier to adjust the load received by the cross member 16, lower case 10, and cover frame 17 during a collision.

[0022] Furthermore, the multiple battery modules 3 are arranged side by side at least in the front-to-rear direction in the battery module housing portion P. The cross member 16 extends in the left-to-right direction between the battery modules 3 lined up in the front-to-rear direction, and the cover frame 17 also extends in the left-to-right direction between the battery modules 3 lined up in the front-to-rear direction.

[0023] 4, with regard to the relationship between the cover frame 17 and the battery modules 3, the upper end of the cover frame 17 may extend in the left-right direction at a height equal to or higher than the upper ends of the battery modules 3. In this case, the cross member 16 may have approximately the same height across the left wall portion 14 and the right wall portion 15, and the height may not decrease from each of the left wall portion 14 and the right wall portion 15 toward the center in the left-right direction.

[0024] Because the upper end of the cover frame 17 extends in the left-right direction at a height equal to or higher than the upper ends of the battery modules 3, when high-temperature gas is generated in the battery modules 3, the high-temperature gas is prevented from flowing between the battery modules 3 lined up in the front-to-rear direction, as shown by the arrows in Fig. 4, and is more likely to flow above the battery modules 3. Then, as shown by the arrows in Fig. 5, the high-temperature gas generated in the battery modules 3 flows rearward above the battery modules 3 toward the pressure release valve 30.

[0025] In contrast, as shown in FIGS. 7 and 8 , if the upper end of the cover frame 17 extends laterally at a height lower than the upper ends of the battery modules 3, when high-temperature gas is generated in the battery modules 3, some of the high-temperature gas generated in the battery modules 3 flows above the cover frame 17, i.e., between the battery modules 3 lined up in the front-to-back direction, as indicated by the arrows in FIG. 7 . Furthermore, as indicated by the arrows in FIG. 8 , the high-temperature gas generated in the battery modules 3 not only flows rearward above the battery modules 3 toward the pressure release valve 30, but also partially flows between the battery modules 3 lined up in the front-to-back direction and then flows laterally between the battery modules 3 lined up in the front-to-back direction. Therefore, the front and rear surfaces of the battery modules 3 come into contact with the high-temperature gas, and the battery modules 3 receive heat from the high-temperature gas, causing their temperatures to rise. When the temperature of the battery modules 3 rises, a thermal chain reaction is more likely to occur between the battery modules 3.

[0026] In this embodiment, the upper end of the cover frame 17 extends in the left-right direction at a height equal to or higher than the upper ends of the battery modules 3. This prevents the high-temperature gas from flowing between the battery modules 3 lined up in the front-to-rear direction when high-temperature gas is generated in the battery modules 3, thereby preventing the battery modules 3 from receiving the heat of the high-temperature gas and increasing in temperature, thereby preventing a thermal chain reaction between the battery modules 3.

[0027] 1 and 6, the battery pack 1 is provided with one or more pressure release valves 30 that can release gas from an internal space (substantially equivalent to the battery module accommodating section P) of the battery pack 1 that is surrounded by the lower case 10 and the upper cover 20 to the outside of the battery pack 1. Also, as shown in FIG. 6, the battery pack 1 is provided with a temperature sensor 40 that is provided in the internal space of the battery pack 1 and that detects the temperature of the internal space of the battery pack 1.

[0028] The pressure release valve 30 is concentrated at the front or rear of the battery pack 1, and the temperature sensor 40 is disposed near the pressure release valve 30. In this embodiment, the pressure release valve 30 and the temperature sensor 40 are concentrated at the rear of the battery pack 1, but they may also be concentrated at the front.

[0029] By consolidating the pressure release valves 30 at the front or rear of the battery pack 1, the flow of high-temperature gas generated in the battery modules 3 is simplified when the gas flows above the battery modules 3 toward the pressure release valve 30, which further prevents the high-temperature gas from getting between the battery modules 3. Furthermore, in addition to simplifying the flow of gas when flowing above the battery modules 3, by arranging the temperature sensor 40 near the pressure release valve 30, the temperature in the internal space of the battery pack 1 can be detected more accurately.

[0030] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiment may be combined in any manner without departing from the spirit of the invention.

[0031] This specification describes at least the following: In parentheses, components corresponding to those in the above-described embodiments are shown as examples, but the present invention is not limited to these.

[0032] (1) A battery pack (battery pack 1) that houses a plurality of battery modules (battery modules 3) each having a plurality of stacked battery cells, The battery pack a lower case (lower case 10) that covers the lower portions of the plurality of battery modules; an upper cover (upper cover 20) that covers the upper portions of the plurality of battery modules; The lower case includes: a bottom plate portion (bottom plate portion 11) that covers the lower portions of the plurality of battery modules; a front wall portion (front wall portion 12) standing upward and extending in the left-right direction at the front portion of the bottom plate portion; a rear wall portion (rear wall portion 13) that stands upward and extends in the left-right direction at the rear of the bottom plate portion; a left wall portion (left wall portion 14) standing upward and extending in the front-rear direction at the left portion of the bottom plate portion; a right wall portion (right wall portion 15) standing upward and extending in the front-rear direction at the right portion of the bottom plate portion, the plurality of battery modules are arranged in a battery module accommodating section (battery module accommodating section P) surrounded by the bottom plate section, the front wall section, the rear wall section, the left wall section, and the right wall section; The lower case includes: a cross member (cross member 16) that stands upward from the bottom plate portion in the battery module accommodating portion and extends continuously in the left-right direction from the left wall portion to the right wall portion; a cover frame (cover frame 17) extending in the left-right direction and covering at least a portion of the upper portion of the cross member; The cross member is made of solid metal and extends in the left-right direction from both left and right ends toward the center in the left-right direction so that the position of the upper end becomes lower, The cover frame is formed of a metal plate and fixed to the cross member. Battery pack.

[0033] According to (1), the load during a collision can be absorbed by both the solid metal cross member provided on the lower case and the cover frame formed from a metal plate. This allows the longitudinal width of the cross member to be reduced, thereby reducing the space required for the cross member in the battery pack and enabling the battery pack to be made more compact. Furthermore, by absorbing the load during a collision with both the cross member and the cover frame, the load received by the cross member during a collision can be reduced, allowing the height of the central region of the cross member to be lowered. This allows the weight of the solid cross member to be reduced, thereby enabling the weight of the battery pack to be reduced.

[0034] (2) The battery pack according to (1), the bottom plate portion, the front wall portion, the rear wall portion, the left wall portion, the right wall portion, and the cross member are made of aluminum and integrally formed, The cover frame is made of iron. Battery pack.

[0035] According to (2), the bottom plate, front wall, rear wall, left wall, right wall, and cross member are all made of aluminum and are integrally molded, which allows the load during a collision to be distributed to the cross member and the lower case. Furthermore, the cover frame is made of iron, which improves heat resistance and makes it easier to adjust the load received by the cross member, lower case, and cover frame during a collision.

[0036] (3) The battery pack according to (1) or (2), In the battery module housing, the plurality of battery modules are arranged side by side in a front-rear direction, The cross member extends in the left-right direction between the battery modules arranged in the front-rear direction, the cover frame extends in the left-right direction between the battery modules arranged in the front-rear direction, The upper end of the cover frame extends in the left-right direction at a height equal to or higher than the upper end of the battery module. Battery pack.

[0037] According to (3), the upper end of the cover frame extends in the left-right direction at a height equal to or higher than the upper ends of the battery modules, which prevents high-temperature gas generated in the battery modules from flowing between the battery modules arranged in the front-to-rear direction and makes it easier for the gas to flow above the battery modules. This prevents the battery modules from receiving heat from the high-temperature gas and increasing in temperature, thereby preventing a thermal chain reaction between the battery modules.

[0038] (4) The battery pack according to (3), The battery pack one or more pressure release valves (pressure release valves 30) capable of releasing gas from an internal space of the battery pack surrounded by the lower case and the upper cover to the outside of the battery pack; a temperature sensor (temperature sensor 40) provided in the internal space of the battery pack to detect the temperature of the internal space of the battery pack; the pressure release valves are concentrated at the front or rear of the battery pack, The temperature sensor is disposed near the pressure release valve. Battery pack.

[0039] According to (4), by integrating the pressure release valves at the front or rear of the battery pack, the flow of high-temperature gas generated in the battery modules is simplified as it flows above the battery modules toward the pressure release valve, which makes it possible to more effectively prevent the high-temperature gas from getting between the battery modules. Furthermore, in addition to simplifying the flow of gas as it flows above the battery modules, by arranging the temperature sensor near the pressure release valve, it is possible to more accurately detect the temperature in the internal space of the battery pack. [Explanation of symbols]

[0040] 1 Battery pack 3 Battery Module 10 Lower Case 11 Bottom plate part 12 Front wall 13 Rear wall 14 Left wall 15 Right wall 16 Cross member 17 Cover Frame 20 Upper cover 30 Pressure relief valve 40 Temperature Sensor P Battery module storage area

Claims

1. A battery pack containing a plurality of battery modules, each of which has a plurality of stacked battery cells, The battery pack a lower case covering lower portions of the plurality of battery modules; an upper cover that covers an upper portion of the plurality of battery modules; The lower case includes: a bottom plate portion covering lower portions of the plurality of battery modules; a front wall portion that stands upward and extends in the left-right direction at a front portion of the bottom plate portion; a rear wall portion that stands upward and extends in the left-right direction at a rear portion of the bottom plate portion; a left wall portion standing upward and extending in the front-rear direction at a left portion of the bottom plate portion; a right wall portion that stands upward and extends in the front-rear direction at a right portion of the bottom plate portion, the plurality of battery modules are arranged in a battery module accommodating section surrounded by the bottom plate section, the front wall section, the rear wall section, the left wall section, and the right wall section, The lower case includes: a cross member that stands upward from the bottom plate portion in the battery module accommodating portion and extends continuously in the left-right direction from the left wall portion to the right wall portion; a cover frame extending in the left-right direction and covering at least a portion of the upper portion of the cross member, The cross member is made of solid aluminum and extends in the left-right direction from both left and right ends toward the center in the left-right direction so that the position of the upper end becomes lower, The cover frame is formed of an iron plate and fixed to the cross member. Battery pack.

2. 2. The battery pack according to claim 1, The bottom plate portion, the front wall portion, the rear wall portion, the left wall portion, the right wall portion, and the cross member are made of aluminum and are integrally formed. Battery pack.

3. 3. The battery pack according to claim 1, In the battery module housing, the plurality of battery modules are arranged side by side in a front-rear direction, The cross member extends in the left-right direction between the battery modules arranged in the front-rear direction, the cover frame extends in the left-right direction between the battery modules arranged in the front-rear direction, The upper end of the cover frame extends in the left-right direction at a height equal to or higher than the upper end of the battery module. Battery pack.

4. 4. The battery pack according to claim 3, The battery pack one or more pressure release valves capable of releasing gas from an internal space of the battery pack surrounded by the lower case and the upper cover to the outside of the battery pack; a temperature sensor provided in the internal space of the battery pack to detect a temperature of the internal space of the battery pack, the pressure release valves are concentrated at the front or rear of the battery pack, The temperature sensor is disposed near the pressure release valve. Battery pack.

5. A battery pack containing a plurality of battery modules, each of which has a plurality of stacked battery cells, The battery pack a lower case covering lower portions of the plurality of battery modules; an upper cover that covers an upper portion of the plurality of battery modules; The lower case includes: a bottom plate portion covering lower portions of the plurality of battery modules; a front wall portion that stands upward and extends in the left-right direction at a front portion of the bottom plate portion; a rear wall portion that stands upward and extends in the left-right direction at a rear portion of the bottom plate portion; a left wall portion standing upward and extending in the front-rear direction at a left portion of the bottom plate portion; a right wall portion that stands upward and extends in the front-rear direction at a right portion of the bottom plate portion, the plurality of battery modules are arranged in a battery module accommodating section surrounded by the bottom plate section, the front wall section, the rear wall section, the left wall section, and the right wall section, The lower case includes: a cross member that stands upward from the bottom plate portion in the battery module accommodating portion and extends continuously in the left-right direction from the left wall portion to the right wall portion; a cover frame extending in the left-right direction and covering at least a portion of the upper portion of the cross member, The cross member is made of a solid first metal material and extends in the left-right direction from both left and right ends toward a center in the left-right direction so that the position of the upper end becomes lower, The cover frame is formed of a second metal plate and fixed to the cross member, The first metal is lighter than the second metal, and the second metal is stronger than the first metal. Battery pack.

Images