Battery pack

Abstract

To provide a battery pack capable of achieving space saving.SOLUTION: A battery pack 20 includes a battery module 21, a first junction board 31, a second junction board 32, and a lower case 40 that accommodates these components. The first junction board 31 and the second junction board 32 are disposed at a front end portion and a rear end portion of the lower case 40, respectively, and are electrically connected to each other via bus bars 71 and 72. The bus bars 71 and 72 extend in a space S between battery modules 21 adjacent to each other in a left-right direction and connect the first junction board 31 and the second junction board 32.SELECTED DRAWING: Figure 3

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 battery unit for driving a vehicle mounted on an electric vehicle or the like. The battery unit includes a plurality of battery modules, a first electrical junction box, a second electrical junction box, and a battery unit case that houses these. The first electrical junction box and the second electrical junction box are electrically connected by a center cable equipped with a high-voltage power line. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-040956 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the center cable is routed in the space above the bus bars that connect the battery modules together, thereby making effective use of the space inside the battery unit case. However, there is still room for improvement in terms of space saving.

[0006] The present invention provides a battery pack that can save space. [Means for solving the problem]

[0007] The present invention provides a plurality of electrical devices each including a cell stack in which a plurality of battery cells are stacked, and a junction board electrically connected to the cell stack; a case that houses the plurality of electrical devices, The plurality of electrical devices include: a first electric device and a second electric device that are respectively arranged at one end and the other end of the case in a predetermined first direction among horizontal directions and are electrically connected to each other via a bus bar; a plurality of third electric devices disposed between the first electric device and the second electric device in the first direction, The bus bar extends into a space between adjacent third electric devices or a space between the third electric device and the case, and connects the first electric device and the second electric device. [Effects of the Invention]

[0008] According to the present invention, the first and second electric devices, which are respectively arranged at one end and the other end of the case, are electrically connected using a bus bar, thereby achieving space savings compared to connecting using a cable. Furthermore, the space between adjacent third electric devices or the space between the third electric device and the case is utilized for extending the bus bar, thereby further achieving space savings. [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. [Figure 7] 10 is a perspective view of bus bars 71 and 72 routed along a rib 44 provided on a lower case 40. 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 41 that covers the lower portions of the multiple battery modules 21, left and right side wall portions 42 that rise upward and extend in the front-to-rear direction at both left and right ends of the bottom plate 41, and multiple cross members 43 that rise upward and extend in the left-to-right direction at an intermediate portion of the bottom plate 41. As shown in FIG. 7 , the lower case 40 also includes a rib 44 that rises upward and extends in the front-to-rear direction at the center of the bottom plate 41 in the left-to-right direction. Furthermore, reinforcing plates 45 are provided on the tops of some of the cross members 43 as needed. The reinforcing plates 45 are, for example, plate-shaped members made of high-tensile steel.

[0013] As shown in FIGS. 2 and 3, 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. The cross member 43 described above is provided between adjacent battery modules 21 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] 3 and 4, bus bars 71 and 72, which are high-voltage power lines connecting the first junction board 31 and the second junction board 32, are arranged in the internal space 60. The bus bars 71 and 72 are high-voltage power lines through which power stored in the battery module 21 flows to be supplied to a vehicle drive motor (described later), with one side being a positive side and the other being a negative side.

[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 bus bars 73 that electrically connect the negative terminals 222 and positive terminals 221 of adjacent battery modules 21. In this embodiment, 13 battery modules 21 are connected in series via the plurality of bus bars 73.

[0023] 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.

[0024] In this way, the second junction board 32 is electrically connected to the 13 battery modules 21 connected in series.

[0025] Next, details of the bus bars 71 and 72 will be described with reference to FIGS. 2 to 4, 6 and 7. FIG.

[0026] The bus bars 71, 72 are formed long and extend in the front-rear direction in the internal space 60 of the battery pack 20. Specifically, the bus bars 71, 72 extend into the space S between the battery modules 21 adjacent in the left-right direction, and electrically connect the first junction board 31 and the second junction board 32. In the space S, the bus bars 71, 72 are arranged at a position lower than the top surfaces of the battery modules 21.

[0027] The first junction board 31 and the second junction board 32 are electrically connected using bus bars 71 and 72, which saves space compared to when cables are used for connection. Furthermore, the bus bars 71 and 72 are disposed in the space S between adjacent battery modules 21 and extend from the front end to the rear end of the lower case 40, which allows for effective use of the space within the lower case 40.

[0028] 3 and 6, parts of the bus bars 71, 72 are arranged in the space S between the adjacent battery modules 21 such that the wider surfaces 71a, 72a face the side surfaces (outer surfaces) of the adjacent battery modules 21. In this way, the space S between the adjacent battery modules 21 can be narrowed.

[0029] The bus bars 71, 72 also have twisted portions 71b, 72b that are twisted along the direction in which they extend in the space S between adjacent battery modules 21. In this embodiment, the twisted portions 71b, 72b are twisted 90 degrees along the direction in which they extend. The twisted portions 71b, 72b allow the wide surfaces 71a, 72a of the bus bars 71, 72 to be positioned so as to face the side surfaces of the adjacent battery modules 21.

[0030] 3 and 7, portions of bus bars 71, 72 extend along ribs 44 provided on bottom plate portion 41 of lower case 40. In this way, when a load due to a collision in the front-rear direction is input to battery pack 20, the input to bus bars 71, 72 can be reduced.

[0031] Furthermore, the bus bars 71, 72 extend in the front-rear direction through a gap formed between the cross member 43 and the reinforcing plate 45 in the space S between adjacent battery modules 21. This prevents the bus bars 71, 72 from protruding upward, thereby preventing the battery pack 20 from becoming larger in the vertical direction.

[0032] The bus bars 71, 72 as described above are configured, for example, in a shape as shown in Fig. 6. The bus bars 71, 72 each include first fastening portions 71c, 72c fastened to terminals of the first junction board 31, first vertical extending portions 71d, 72d extending downward from the first fastening portions 71c, 72c, first front-rear extending portions 71e, 72e extending rearward from the lower ends of the first vertical extending portions 71d, 72d, the twisted portions 71b, 72b formed at the rear ends of the first front-rear extending portions 71e, 72e, and the twisted portions 71b, 72b. 2b, second front-to-rear extending portions 71f, 72f extending rearward, second vertical extending portions 71g, 72g extending upward from the rear ends of the second front-to-rear extending portions 71f, 72f, left-to-right extending portions 71h, 72h extending rightward from the upper ends of the second vertical extending portions 71g, 72g, and second fastening portions 71i, 72i provided at the right ends of the left-to-right extending portions 71h, 72h and fastened to terminals of the second junction board 32.

[0033] In such busbars 71, 72, the first front-to-rear extending portions 71e, 72e, the twisted portions 71b, 72b, and the second front-to-rear extending portions 71f, 72f are arranged in the space S, and the wide surfaces 71a, 72a of the second front-to-rear extending portions 71f, 72f face the side surfaces of the adjacent battery modules 21.

[0034] It is preferable that bus bars 71, 72 do not include any welded portions. Specifically, it is preferable that bus bars 71, 72 are formed from a single member. Since they do not include any welded portions, it is possible to suppress a decrease in conductivity due to welding, and it is also possible to form bus bars 71, 72 with high strength.

[0035] Furthermore, bus bars 71, 72 can be made of aluminum, copper, or an alloy thereof. In particular, when bus bars 71, 72 are made of aluminum, the weight of battery pack 20 can be reduced.

[0036] Since aluminum has a relatively low conductivity compared to copper, when bus bars 71, 72 are made of aluminum, they need to be structured to ensure a sufficient allowable current for bus bars 71, 72. Specifically, aluminum bus bars 71, 72 need to have a larger cross-sectional area (specifically, width and thickness of the bus bars) than copper bus bars.

[0037] Therefore, it is desirable to design the cross-sectional areas of the aluminum busbars 71, 72 based on the allowable current value if the busbars were made of copper. Specifically, the cross-sectional areas of the aluminum busbars 71, 72 are set so that the allowable current value for the aluminum busbars 71, 72 is approximately equal to (or exceeds) the allowable current value for the copper busbars. In this way, it is possible to design the cross-sectional areas of the busbars 71, 72 so that the current value allowable for the copper busbars can also flow through the aluminum busbars 71, 72.

[0038] As described above, in the electrical path from the plurality of battery modules 21 (upstream side) to the front-wheel drive unit 11 (downstream side), the bus bars 71, 72 are provided downstream of the second junction board 32, which includes a circuit breaker. Therefore, even if a thermal chain reaction occurs in the plurality of battery modules 21 and the bus bars 71, 72 are affected by heat, the safety of the electrical path is ensured by activating the circuit breaker. Therefore, the bus bars 71, 72 may be made of aluminum, which has lower heat resistance than copper.

[0039] 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.

[0040] For example, in the above-described embodiment, the bus bars 71, 72 are arranged in the space S between adjacent battery modules 21, but they may also be arranged in the space between the battery module 21 and the lower case 40 (side wall portion 42).

[0041] Furthermore, in the above-described embodiment, the bus bars 71, 72 electrically connect the first junction board 31 arranged near the front end of the battery pack 20 and the second junction board 32 arranged near the rear end of the battery pack 20, but may also be configured to connect electrical equipment other than junction boards (e.g., battery module 21).

[0042] Furthermore, 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 a plurality of battery cells stacked without being modularized.

[0043] 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.

[0044] 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.

[0045] (1) A plurality of electrical devices (battery modules 21, first junction board 31, second junction board 32) including a cell stack (battery module 21) in which a plurality of battery cells are stacked, and junction boards (first junction board 31, second junction board 32) electrically connected to the cell stack; a case (lower case 40) that houses the plurality of electrical devices, The plurality of electrical devices include: a first electric device (first junction board 31) and a second electric device (second junction board 32) that are respectively arranged at one end and the other end of the case in a predetermined first direction among horizontal directions and are electrically connected to each other via bus bars (bus bars 71, 72); a plurality of third electric devices (battery modules 21) disposed between the first electric device and the second electric device in the first direction, The bus bar extends into a space (space S) between adjacent third electric devices or a space between the third electric device and the case, and connects the first electric device and the second electric device. Battery pack.

[0046] According to (1), the first electric device and the second electric device are electrically connected using a bus bar, which saves space compared to connecting them using a cable. Also, the bus bar is disposed in the space between adjacent third electric devices or the space between the third electric device and the case, and extends from one end of the case to the other end, which makes it possible to effectively utilize the space within the case.

[0047] (2) The battery pack according to (1), At least a portion of the bus bar is In the space between the adjacent third electric devices, the wider surface (surfaces 71a, 72a) is arranged to face the outer surface of the adjacent third electric device, or In the space between the third electric device and the case, the wider surfaces (surfaces 71a, 72a) are arranged to face the outer surfaces of the third electric device and the case. Battery pack.

[0048] According to (2), the space between adjacent third electric devices can be narrowed.

[0049] (3) The battery pack according to (2), The bus bar has twisted portions (twisted portions 71b, 72b) twisted along the extending direction in the space between the adjacent third electric devices or the space between the third electric device and the case. Battery pack.

[0050] According to (3), since the bus bar has a twisted portion, the wider side of the bus bar can be arranged to face the adjacent third electric device, or to face the third electric device and the case.

[0051] (4) A battery pack according to any one of (1) to (3), the first electric device and the second electric device are the junction boards that electrically connect the cell stack and drive motors (front wheel drive unit 11, rear wheel drive unit 13) mounted on a vehicle, The bus bar is a high-voltage power line through which power stored in the cell stack and supplied to the drive motor flows. Battery pack.

[0052] According to (4), by configuring the high-voltage power line with a bus bar, it is possible to reduce the space required for the battery pack compared to when the high-voltage power line is configured with a cable.

[0053] (5) A battery pack according to any one of (1) to (4), the third electric device includes a plurality of the cell stacks arranged in a second direction of the horizontal direction that is orthogonal to the first direction, the bus bar extends into a space between the cell stacks adjacent to each other in the second direction and connects the first electric device and the second electric device. Battery pack.

[0054] According to (5), the space between adjacent cell stacks can be effectively used as a space for routing the bus bars.

[0055] (6) A battery pack according to any one of (1) to (5), a rib (rib 44) extending along the first direction is provided on a bottom plate portion (bottom plate portion 41) of the case, At least a portion of the bus bar extends along the rib. Battery pack.

[0056] According to (6), at least a portion of the bus bar extends along the rib, so that when a load is input to the battery pack in the first direction, the input to the bus bar can be reduced.

[0057] (7) A battery pack according to any one of (1) to (6), The bus bar does not include any welded portions. Battery pack.

[0058] According to (7), the decrease in electrical conductivity due to welding can be suppressed.

[0059] (8) A battery pack according to any one of (1) to (7), The bus bar is formed of aluminum, copper, or an alloy thereof. Battery pack.

[0060] According to (8), the busbar can be made of aluminum, copper, or an alloy thereof.

[0061] (9) The battery pack according to (8), The bus bar is formed of aluminum. Battery pack.

[0062] According to (9), the weight of the battery pack can be reduced.

[0063] (10) The battery pack according to (9), The cross-sectional area of ​​the bus bar is designed based on an allowable current value assuming that the bus bar is made of copper. Battery pack.

[0064] According to (10), it is possible to design the cross-sectional area of ​​the busbar so that the current value allowed in the copper busbar can also be passed through the aluminum busbar. [Explanation of symbols]

[0065] 11 Front wheel drive unit (drive motor) 13 Rear wheel drive unit (drive motor) 20 Battery pack 21 Battery module (cell stack, third electrical device) 31 First junction board (first electrical equipment) 32 Second junction board (second electrical equipment) 40 Lower case (case) 41 Bottom plate part 44 Ribs 71, 72 Busbars 71a, 72a wide surface 71b, 72b twisted part

Claims

1. a plurality of electrical devices each including a cell stack in which a plurality of battery cells are stacked, and a junction board electrically connected to the cell stack; a case that houses the plurality of electrical devices, The plurality of electrical devices include: a first electric device and a second electric device, which are respectively arranged at one end and the other end of the case in a predetermined first direction among horizontal directions and are electrically connected to each other via a bus bar; a plurality of third electric devices disposed between the first electric device and the second electric device in the first direction, the bus bar extends into a space between adjacent third electric devices or a space between the third electric device and the case, and connects the first electric device and the second electric device. Battery pack.

2. 2. The battery pack according to claim 1, At least a portion of the bus bar is In the space between the adjacent third electric devices, the wider surface is arranged to face the outer surface of the adjacent third electric device, or In the space between the third electric device and the case, the wider surface is disposed so as to face the outer surfaces of the third electric device and the case. Battery pack.

3. 3. The battery pack according to claim 2, the bus bar has a twisted portion twisted along the extending direction in a space between adjacent ones of the third electric devices or in a space between the third electric device and the case; Battery pack.

4. 4. The battery pack according to claim 1, the first electrical device and the second electrical device are the junction boards that electrically connect the cell stack and a drive motor mounted on a vehicle, The bus bar is a high-voltage power line through which power stored in the cell stack and supplied to the drive motor flows. Battery pack.

5. 4. The battery pack according to claim 1, the third electric device includes a plurality of the cell stacks arranged in a second direction of the horizontal direction that is orthogonal to the first direction, the bus bar extends into a space between the cell stacks adjacent to each other in the second direction and connects the first electric device and the second electric device. Battery pack.

6. 4. The battery pack according to claim 1, a rib extending along the first direction is provided on the bottom plate portion of the case, At least a portion of the bus bar extends along the rib. Battery pack.

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

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

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

10. 10. The battery pack according to claim 9, The cross-sectional area of ​​the bus bar is designed based on an allowable current value assuming that the bus bar is made of copper. Battery pack.

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