Battery pack

Abstract

To sufficiently ensure an allowable current of a bus bar regardless of material, while achieving space saving.SOLUTION: A battery pack 20 includes: a plurality of battery modules 21; first to third bus bars 73, 74, and 75 for electrically connecting the plurality of battery modules 21; and a lower case 40 and an upper cover 50 that accommodate the plurality of battery modules 21 and the first to third bus bars 73, 74, and 75. The first to third bus bars 73, 74, and 75 each have fastening portions 731, 741, and 751 provided at both end portions and fastened to terminals 221 and 222 of adjacent battery modules 21, and wide portions 732, 742, and 752 provided between the fastening portions 731, 741, and 751 and configured to have widths W12, W22, and W32 greater than those of the fastening portions 731, 741, and 751, and the wide portions 732, 742, and 752 are disposed between adjacent battery modules 21.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a battery pack. [Background technology]

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been conducted to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] For example, Patent Document 1 describes a plurality of battery cells / modules that are mounted on a vehicle such as an electric car and are electrically coupled by bus bars. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-514926 Summary of the Invention [Problem to be solved by the invention]

[0005] The allowable current of a bus bar such as that described in Patent Document 1 varies depending on the material and size. There is a demand for a technology that can ensure a sufficient allowable current of a bus bar regardless of the material while avoiding an increase in the size of the battery pack.

[0006] The present invention provides a battery pack that can ensure a sufficient bus bar allowable current regardless of the material and can also save space. [Means for solving the problem]

[0007] The present invention provides a plurality of electrical devices including at least a cell stack in which a plurality of battery cells are stacked; a bus bar that electrically connects the plurality of electrical devices; a case that accommodates the plurality of electrical devices and the bus bar, The bus bar is fastening portions provided at both ends and fastened to terminals of the plurality of electrical devices; a wide portion provided between the fastening portions and configured to be wider than the fastening portions; At least a portion of the wide portion of the bus bar is disposed between adjacent pieces of electrical equipment. [Effects of the Invention]

[0008] According to the present invention, the widened portions increase the cross-sectional area of ​​the busbar, thereby increasing the conductivity of the busbar and ensuring a sufficient allowable current for the busbar regardless of the busbar material. Furthermore, the space between adjacent electrical devices can be utilized for arranging the widened portions, thereby saving space in the battery pack. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a battery pack 20 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the battery pack 20 with the upper cover 50 removed. [Figure 3] FIG. 2 is a top view of the battery pack 20 with the upper cover 50 removed. [Figure 4] FIG. 10 is a schematic diagram showing wiring between a first junction board 31 arranged on the front side and a second junction board 32 arranged on the rear side. [Figure 5] 10 is a schematic diagram showing wiring between a plurality of battery modules 21 and a second junction board 32 (dotted chain lines). [Figure 6] FIG. 2 is an enlarged perspective view of a first bus bar 73. [Figure 7] 10 is an enlarged perspective view of a first bus bar 73 in a state in which adjacent battery modules 21 are electrically connected. FIG. [Figure 8] FIG. 2 is an enlarged perspective view of a second bus bar 74. [Figure 9] 10 is an enlarged perspective view of a second bus bar 74 in a state in which adjacent battery modules 21 are electrically connected. FIG. [Figure 10] FIG. 2 is an enlarged perspective view of a third bus bar 75. [Figure 11] 10 is an enlarged perspective view of a third bus bar 75 in a state in which adjacent battery modules 21 are electrically connected. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of a battery pack of the present invention will be described below with reference to the accompanying drawings. The drawings are to be viewed in accordance with the directions indicated by the reference numerals. For simplicity and clarity, the front, rear, left, right, and up and down directions are described in accordance with the directions as seen by the driver of a vehicle equipped with the battery pack. In the drawings, the front of the vehicle is indicated as Fr, the rear as Rr, the left as L, the right as R, the top as U, and the bottom as D.

[0011] 1 to 3 is mounted, for example, under the floor of a vehicle such as an electric vehicle. The battery pack 20 includes a lower case 40 with an open top and an upper cover 50 that covers the top of the lower case 40. An internal space 60 surrounded by the lower case 40 and the upper cover 50 is formed in the battery pack 20.

[0012] The lower case 40 includes a bottom plate portion 41 that covers the lower portions of the plurality of battery modules 21, and left and right side wall portions 42 that stand upward and extend in the front-to-rear direction at both left and right ends of the bottom plate portion 41.

[0013] The battery pack 20 includes a plurality of battery modules 21, a first junction board 31, and a second junction board 32, which are housed in an internal space 60.

[0014] Each battery module 21 has a substantially rectangular parallelepiped shape. In each battery module 21, a plurality of battery cells are stacked. The plurality of battery cells in each battery module 21 are electrically connected by a bus bar plate (not shown) or the like. The battery module 21 is an example of a "cell stack" of the present invention. A positive terminal 221 and a negative terminal 222, which are input / output terminals, are provided on the upper part of each battery module 21. In this embodiment, the positive terminal 221 and the negative terminal 222 are arranged side by side in the short direction at the upper part of each battery module 21, at one end on one side in the longitudinal direction when viewed from the top-bottom direction.

[0015] Each battery module 21 is arranged in the internal space 60 so that its longitudinal direction, as viewed from the top-bottom direction, extends in the vehicle width direction and its short side extends in the front-to-rear direction. Furthermore, each battery module 21 is arranged in the internal space 60 so that the side on which the positive terminal 221 and the negative terminal 222 are provided in the longitudinal direction is the center of the vehicle width direction.

[0016] The battery modules 21 are arranged in two rows in the left-right direction, side by side in the front-rear direction, for a total of 13. Specifically, seven battery modules 21 are arranged in the right row, side by side in the front-rear direction, and six battery modules 21 are arranged in the left row, side by side in the front-rear direction.

[0017] The first junction board 31 is housed in the internal space 60 and is disposed near the front end of the battery pack 20. More specifically, the first junction board 31 is disposed in the internal space 60 above the frontmost battery modules 21 arranged in the left-right direction, straddling the frontmost battery modules 21 arranged in the left-right direction.

[0018] The second junction board 32 is housed in the internal space 60 and is disposed near the rear end of the battery pack 20. More specifically, the second junction board 32 is disposed in the internal space 60 above the battery module 21 that is disposed at the rearmost position in the right-hand row.

[0019] As shown in FIG. 4, high-voltage power lines 71 and 72 that connect the first junction board 31 and the second junction board 32 are laid in the internal space 60.

[0020] The first junction board 31 is electrically connected to the front-wheel drive unit 11, which includes a motor that drives the front wheels, and the charger 12, which receives power supplied from an external charger. The first junction board 31 is also electrically connected to auxiliary equipment (not shown) (such as an air-conditioning heater and an air-conditioning compressor). The first junction board 31 includes a power input / output circuit for the front-wheel drive unit 11, a power input / output circuit for the charger 12, and a power input / output circuit for the auxiliary equipment.

[0021] The second junction board 32 is electrically connected to the first junction board 31 as well as to the battery module 21 and the rear-wheel drive unit 13, which includes a motor that drives the rear wheels. The second junction board 32 includes a power input / output circuit for the battery module 21 and a power input / output circuit for the rear-wheel drive unit 13. The second junction board 32 also includes a circuit breaker, which is an electrical component that cuts off the flow of electricity to the battery pack 20 in the event of an abnormality.

[0022] 3 and 5, the battery pack 20 includes a plurality of first bus bars 73 and second bus bars 74 that electrically connect the negative terminals 222 of a battery module 21 to the positive terminals 221 of adjacent battery modules 21 in the front-rear direction. Adjacent battery modules 21 in the front-rear direction may be adjacent to each other across a distance K1 or across a distance K2 that is narrower than the distance K1. Adjacent battery modules 21 across the distance K1 are electrically connected to each other via the first bus bars 73, and adjacent battery modules 21 across the distance K2 are electrically connected to each other via the second bus bars 74. Note that, in the spaces K1 and K2, a plurality of cross members are provided that rise upward from the bottom plate portion 41 of the lower case 40 and extend in the left-right direction.

[0023] The battery pack 20 further includes a third bus bar 75 that electrically connects the negative terminal 222 of one of the left and right battery modules 21 located at the forefront to the positive terminal 221 of the other of the left and right battery modules 21 located at the forefront. The two forefront battery modules 21 are adjacent to each other in the left-right direction with a gap K3 (narrower than the gap K1). The battery modules 21 adjacent to each other with the gap K3 between them are electrically connected via the third bus bar 75. In this way, in this embodiment, 13 battery modules 21 are connected in series.

[0024] The battery pack 20 further includes, in the internal space 60, a positive side bus bar 76 that electrically connects the second junction board 32 to the positive terminal 221 of the battery module 21 located at the rear end of the left column, and a negative side bus bar 77 that electrically connects the second junction board 32 to the negative terminal 222 of the battery module 21 located at the rear end of the right column.

[0025] In this way, the second junction board 32 is electrically connected to the 13 battery modules 21 connected in series.

[0026] Next, the first to third bus bars 73, 74, 75 will be described in detail with reference to Figures 6 to 11. First, the configuration common to the first to third bus bars 73, 74, 75 will be described.

[0027] The first to third bus bars 73, 74, 75 have a pair of fastening portions 731, 741, 751 provided at both ends and fastened to the terminals 221, 222 of adjacent battery modules 21, and wide portions 732, 742, 752 provided between the pair of fastening portions 731, 741, 751 and configured with widths W12, W22, W32 wider than widths W11, W21, W31 of the fastening portions 731, 741, 751. The fastening portions 731, 741, 751 are fastened to the terminals 221, 222 of the battery modules 21 by, for example, bolts. Here, "width" refers to the length in a direction perpendicular to the direction in which the fastening portions 731, 741, 751 extend. The thickness of the first to third bus bars 73, 74, 75 is uniform at the fastening portions 731, 741, 751 and the wide portions 732, 742, 752.

[0028] At least a portion of the wide portions 732, 742, 752 of the first to third bus bars 73, 74, 75 is disposed between adjacent battery modules 21. In the example shown in FIGS. 6 to 11, the entire wide portions 732, 742, 752 are disposed between adjacent battery modules 21.

[0029] With such first to third bus bars 73, 74, 75, the cross-sectional area is increased by the wide portions 732, 742, 752, which increases the conductivity of the first to third bus bars 73, 74, 75, and ensures a sufficient allowable current for the first to third bus bars 73, 74, 75 regardless of the material of the first to third bus bars 73, 74, 75. Furthermore, the space between adjacent battery modules 21 can be utilized for arranging the wide portions 732, 742, 752, so that the battery pack 20 can be made more compact even if the wide portions 732, 742, 752 are provided. Furthermore, because the cross-sectional area of ​​the first to third bus bars 73, 74, 75 is increased, the wide portions 732, 742, 752 can fully withstand fastening stress generated by bolt fastening at the fastening portions 731, 741, 751, for example.

[0030] Furthermore, heat dissipation is improved because the surface area of ​​first to third bus bars 73, 74, 75 is increased by wide portions 732, 742, 752. Also, the presence of wide portions 732, 742, 752 gives the first to third bus bars 73, 74, 75 a distinctive shape, which helps prevent incorrect assembly of first to third bus bars 73, 74, 75.

[0031] It is preferable that the first to third bus bars 73, 74, 75 do not include any welded portions. For example, the first to third bus bars 73, 74, 75 are integrally formed by press-bending a single metal plate material. Because they do not include any welded portions, it is possible to prevent a decrease in conductivity of the first to third bus bars 73, 74, 75 due to welding, and the first to third bus bars 73, 74, 75 can be formed with high strength.

[0032] The first to third bus bars 73, 74, 75 are formed from a metal plate material made of aluminum, copper, or an alloy thereof. In particular, in order to reduce weight, the first to third bus bars 73, 74, 75 of this embodiment are formed from aluminum. Although aluminum has a relatively low conductivity compared to copper, the first to third bus bars 73, 74, 75 are provided with wide portions 732, 742, 752, so that the allowable current of the first to third bus bars 73, 74, 75 can be sufficiently ensured.

[0033] The widths W12, W22, and W32 of the wide portions 732, 742, and 752 of the first to third bus bars 73, 74, and 75, which are made of aluminum, are designed based on the allowable current value when the bus bars electrically connecting the multiple battery modules 21 are assumed to be made of copper. Specifically, the widths W12, W22, and W32 of the wide portions 732, 742, and 752 are set so that the allowable current value of the first to third bus bars 73, 742, and 75, which have the wide portions 732, 742, and 752 and are made of aluminum, is approximately equal to (or exceeds) the allowable current value of a copper bus bar that does not have a wide portion. In this case, it is assumed that the thicknesses of the aluminum first to third bus bars 73, 74, and 75 and the copper bus bars are the same. This allows the widths W12, W22, and W32 to be appropriately designed.

[0034] The material forming the first to third bus bars 73, 74, and 75 desirably has a material yield strength of 195 MPa or more and a fatigue limit of 70 MPa or more. The material yield strength is, for example, 0.2% yield strength, which is the stress value that causes 0.2% plastic strain when unloaded in a tensile test of a metal material that does not have a clear yield point. The fatigue limit is the stress value at which a material does not suffer fatigue failure even when subjected to a certain amount of repeated stress. In this way, the first to third bus bars 73, 74, and 75 can be provided with sufficient yield strength and fatigue limit.

[0035] Furthermore, it is preferable that the widths W12, W22, and W32 of the wide portions 732, 742, and 752 are set to widths that do not cause the first to third bus bars 73, 74, and 75 to resonate in response to vehicle vibrations, thereby preventing loosening of the fastening portions 731, 741, and 751 (specifically, loosening of the bolt fastening) due to resonance.

[0036] Next, the second and third bus bars 74, 75 will be described with reference to FIGS.

[0037] The second and third bus bars 74, 75 are provided between a pair of fastening portions 741, 751, and further have bent portions 743, 753 that bend toward the space S sandwiched between the outer surfaces (specifically, side surfaces) of adjacent battery modules 21. The space S is a space corresponding to the interval K2 or the interval K3 between the adjacent battery modules 21 described above. Furthermore, at least a portion of the wide portions 742, 752 of the second and third bus bars 74, 75 are disposed in the space S. In the example shown in FIGS. 8 to 11, the wide portions 742, 752 are entirely disposed in the space S.

[0038] The second and third bus bars 74, 75 are bent so that at least a portion of the wide portions 742, 752 is disposed in the space S sandwiched between the outer surfaces of the adjacent battery modules 21, thereby enabling the battery pack 20 to be made more compact.

[0039] Further, the second and third bus bars 74, 75 have folded portions 744, 754 that are folded back in a substantially U-shape in the space S. Such folded portions 744, 754 allow the wide portions 742, 752 to be housed compactly within the space S, thereby achieving further space saving of the battery pack 20. Furthermore, the folded portions 744, 754 can fully withstand the fastening stress generated in the fastening portions 731, 741, 751 due to elastic deformation.

[0040] Folded portion 744 of second bus bar 74 is formed in wide portion 742. Specifically, folded portion 744 is formed by folding back a middle portion of wide portion 742. In this way, the strength of folded portion 744 can be improved.

[0041] On the other hand, folded portion 754 of third bus bar 75 is formed at a position different from wide portion 752. For example, folded portion 754 of third bus bar 75 is narrower than wide portion 752, and is formed at one end of wide portion 752 in the width direction. In this way, folded portion 754 is formed at a position different from wide portion 752, so the width of folded portion 754 can be set arbitrarily, making it easier to process folded portion 754.

[0042] The bent portions 743, 753 and the folded portions 744, 754 of the second and third bus bars 74, 75 are formed by bending a metal plate material, which makes it possible to easily process the bent portions 743, 753 and the folded portions 744, 754.

[0043] 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.

[0044] For example, in the above-described embodiment, a battery module 21 was shown as an example of a "cell stack," but the "cell stack" is not limited to this and may also be multiple battery cells stacked without being modularized.

[0045] In the above-described embodiment, the battery modules 21 are arranged in two rows in the left-right direction and in the front-rear direction in the internal space 60 of the battery pack 20, but the arrangement can be set arbitrarily. Furthermore, the number of battery modules 21 housed in the internal space 60 is not limited to 13 and can be set arbitrarily.

[0046] Furthermore, in the above-described embodiment, the first to third bus bars 73, 74, 75 electrically connect adjacent battery modules 21 in the front-to-rear or left-to-right direction, but they may also be configured to connect electrical devices other than the battery modules 21 (for example, the first junction board 31 or the second junction board 32).

[0047] This specification describes at least the following items. Note that the components in parentheses correspond to those in the above-described embodiment, but are not limited to these.

[0048] (1) A plurality of electrical devices (battery modules 21, a first junction board 31, a second junction board 32) including at least a cell stack (battery module 21) in which a plurality of battery cells are stacked; bus bars (first bus bar 73, second bus bar 74, third bus bar 75) that electrically connect the plurality of electrical devices; a case (a lower case 40, an upper cover 50) that houses the plurality of electrical devices and the bus bar; The bus bar is fastening portions (fastening portions 731, 741, 751) provided at both ends and fastened to terminals (positive terminal 221, negative terminal 222) of the plurality of electrical devices; and wide portions (wide portions 732, 742, 752) provided between the fastening portions and configured to be wider than the fastening portions, At least a part of the wide portion of the bus bar is disposed between adjacent ones of the electric devices. Battery pack.

[0049] According to (1), the widened portion increases the cross-sectional area of ​​the busbar, which increases the conductivity of the busbar and ensures a sufficient allowable current for the busbar regardless of the busbar material. Furthermore, the space between adjacent electrical devices can be utilized for arranging the widened portion, thereby enabling the battery pack to be space-saving even when the widened portion is provided. Furthermore, the increased cross-sectional area of ​​the busbar allows the widened portion to fully absorb stress generated at, for example, the fastening portion.

[0050] In (1), the electrical device fastened to the bus bar at the fastening portion is not limited to the cell stack, and may be a device other than the cell stack.

[0051] (2) The battery pack according to (1), the bus bars (second bus bar 74, third bus bar 75) further have bent portions (bent portions 743, 753) that are provided between the fastening portions and bend toward a space (space S) sandwiched between outer surfaces of the adjacent electrical devices, At least a portion of the wide portion of the bus bar is disposed in the space. Battery pack.

[0052] According to (2), the bus bar is bent and at least a part of the wide portion is disposed in the space between the outer surfaces of the adjacent electrical devices, thereby making it possible to reduce the space required for the battery pack.

[0053] (3) The battery pack according to (2), The bus bar (second bus bar 74) has a folded portion (folded portion 744) that is folded back in a substantially U-shape in the space, The folded portion is formed in the wide portion. Battery pack.

[0054] According to (3), since the folded portion is formed in the wide portion, the strength of the folded portion can be improved.

[0055] (4) The battery pack according to (2), The bus bar (third bus bar 75) has a folded portion (folded portion 754) that is folded back in a substantially U-shape in the space, The folded portion is formed at a position different from the wide portion. Battery pack.

[0056] According to (4), the folded portion is formed at a position different from the wide portion, so that the folded portion is easy to process.

[0057] (5) A battery pack according to any one of (2) to (4), the bent portion of the bus bar is formed by bending. Battery pack.

[0058] According to (5), the bent portion can be easily processed.

[0059] (6) A battery pack according to any one of (1) to (5), The bus bar does not include any welded portions. Battery pack.

[0060] According to (6), the decrease in electrical conductivity due to welding can be suppressed.

[0061] (7) A battery pack according to any one of (1) to (6), The bus bar is formed of aluminum, copper, or an alloy thereof. Battery pack.

[0062] According to (7), the busbar can be made of aluminum, copper, or an alloy thereof.

[0063] (8) The battery pack according to (7), The bus bar is formed of aluminum. Battery pack.

[0064] According to (8), even when aluminum, which has a relatively low conductivity, is used as the material for the bus bar, the wide portion can ensure a sufficient allowable current for the bus bar.

[0065] (9) The battery pack according to (8), a width of the wide portion of the bus bar is designed based on an allowable current value on the assumption that the bus bar electrically connecting the plurality of electrical devices is made of copper; Battery pack.

[0066] According to (9), it is possible to design an appropriate width of the busbar.

[0067] (10) A battery pack according to any one of (1) to (9), The material forming the bus bar has a material yield strength of 195 MPa or more and a fatigue limit of 70 MPa or more. Battery pack.

[0068] According to (10), the busbar can have sufficient strength and fatigue limit. [Explanation of symbols]

[0069] 20 Battery pack 21 Battery module (cell stack, electrical equipment) 221 positive terminal (terminal) 222 negative terminal (terminal) 31 First junction board (electrical equipment) 32 Second junction board (electrical equipment) 40 Lower case (case) 50 Upper cover (case) 73 First bus bar (bus bar) 731 Fastening part 732 Wide section 74 Second bus bar (bus bar) 741 Fastening part 742 Wide section 743 Bend 744 Turning section 75 3rd bus bar (bus bar) 751 Fastening part 752 Wide section 753 Bend 754 Turning section

Claims

1. a plurality of electrical devices including at least a cell stack in which a plurality of battery cells are stacked; a bus bar that electrically connects the plurality of electrical devices; a case that accommodates the plurality of electrical devices and the bus bar, The bus bar is fastening portions provided at both ends and fastened to terminals of the plurality of electrical devices; a wide portion provided between the fastening portions and configured to be wider than the fastening portions; At least a part of the wide portion of the bus bar is disposed between adjacent ones of the electric devices. Battery pack.

2. 2. The battery pack according to claim 1, the bus bar further includes a bent portion provided between the fastening portions and bent toward a space sandwiched between outer surfaces of the adjacent electrical devices, At least a portion of the wide portion of the bus bar is disposed in the space. Battery pack.

3. 3. The battery pack according to claim 2, the bus bar has a folded portion folded back in a substantially U-shape in the space, The folded portion is formed in the wide portion. Battery pack.

4. 3. The battery pack according to claim 2, the bus bar has a folded portion folded back in a substantially U-shape in the space, The folded portion is formed at a position different from the wide portion. Battery pack.

5. 3. The battery pack according to claim 2, the bent portion of the bus bar is formed by bending. Battery pack.

6. 6. The battery pack according to claim 1, The bus bar does not include any welded portions. Battery pack.

7. 6. The battery pack according to claim 1, The bus bar is formed of aluminum, copper, or an alloy thereof. Battery pack.

8. 8. The battery pack according to claim 7, The bus bar is formed of aluminum. Battery pack.

9. 9. The battery pack according to claim 8, a width of the wide portion of the bus bar is designed based on an allowable current value on the assumption that the bus bar electrically connecting the plurality of electrical devices is made of copper; Battery pack.

10. 6. The battery pack according to claim 1, The material forming the bus bar has a material yield strength of 195 MPa or more and a fatigue limit of 70 MPa or more. Battery pack.

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