Terminal and busbar fixing structure and battery pack

Abstract

Securely and efficiently mount the terminals and busbars in a space-saving manner. [Solution] The terminal and busbar fixing structure comprises a pair of external terminals 22, each having a flat plate portion 22C, and a clip-shaped busbar 24 that clamps each flat plate portion 22C and is welded to each flat plate portion 22C.

Description

Technical Field

[0001] The present invention relates to a fixing structure for a terminal and a bus bar, and a battery pack.

Background Art

[0002] The terminal joining structure of the bus bar disclosed in Patent Document 1 below has a welded portion where a joining surface to be joined by welding is arranged with respect to the tip of a rod-shaped terminal, and is provided at a position separated from the welded portion. It has a terminal holding portion that restricts the movement of the terminal in the welded portion when the base end portion of the terminal is inserted. Thereby, when joining the bus bar and the electronic device terminal by welding, the positional relationship between the joining portion of the bus bar and the terminal is stably maintained to obtain a good joining state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in in-vehicle batteries, a cell-to-pack method may be adopted in which the battery module is abolished and the combination of battery cells is directly mounted on the vehicle as a battery pack. When manufacturing a battery pack using the cell-to-pack method, the terminals of a plurality of battery cells are fixed to each other using a bus bar. However, if the terminal and the bus bar are fixed only by caulking, there is a problem that the resistance value increases due to oxidation of the interface due to aging deterioration. On the other hand, when the terminal and the bus bar are fixed by welding, a pressing jig for pressing the bus bar from above is used to measure the gap between the bus bar and the terminal, so space is required in the height direction of the battery pack. As a result, it becomes difficult to miniaturize the battery pack in the height direction and to improve the stacking efficiency of battery cells in the battery pack.

[0005] In consideration of the above facts, the present invention aims to provide a terminal and busbar fixing structure and a battery pack that can appropriately fix the terminal and busbar in a space-saving manner. [Means for solving the problem]

[0006] The terminal and busbar fixing structure of the first embodiment comprises a pair of terminals, each having a plate-shaped flat portion, and a clip-shaped busbar that clamps each of the flat portions and is welded to each of the flat portions.

[0007] In the first embodiment, the flat plate portions of a pair of terminals are clamped by a clip-shaped busbar and welded to the busbar. By clamping the flat plate portion of each terminal by the busbar in this way, welding can be performed while maintaining a constant gap between each flat plate portion and the busbar, and welding can be performed in confined spaces. Therefore, the terminals and busbars can be properly fixed in a space-saving manner.

[0008] In the second embodiment, the terminal and busbar fixing structure is held between the busbar with the flat plate portions abutting against each other, as in the first embodiment.

[0009] In the second embodiment, the flat plate portions of a pair of terminals are abutted against each other and then clamped and welded to the busbar, making it easy to weld each flat plate portion equally to the busbar.

[0010] In the third embodiment, the terminal and busbar fixing structure is such that, in the first embodiment, the flat plate portions are overlapped and sandwiched between the busbar.

[0011] In the third embodiment, the flat plates of the pair of terminals are overlapped and sandwiched between the busbar and welded, making it easier to reduce the space required for arranging the pair of terminals compared to the second embodiment.

[0012] The fourth embodiment of the battery pack comprises a battery case, a plurality of battery cells housed side by side within the battery case, each having a plate-shaped flat portion for its terminals, and a plurality of clip-shaped busbars that clamp each of the flat portions of adjacent battery cells and are welded to each of the flat portions.

[0013] In the fourth embodiment, multiple battery cells housed side by side in a battery case are each provided with terminals having a plate-shaped flat portion. Each flat portion of adjacent battery cells is clamped by a clip-shaped busbar and welded to the busbar. By clamping the flat portion of each terminal with the busbar in this way, welding can be performed while maintaining a constant gap between each flat portion and the busbar, and welding can be performed in confined spaces. Therefore, the terminals and busbars can be properly fixed in a space-saving manner. [Effects of the Invention]

[0014] As described above, the terminal and busbar fixing structure and battery pack according to the present invention allow for proper and space-saving fixing of the terminal and busbar. [Brief explanation of the drawing]

[0015] [Figure 1] This is a plan view showing the main part of the battery pack according to the embodiment. [Figure 2] This is a perspective view showing a portion of the battery pack. [Figure 3] This is a perspective view showing the state of adjacent battery cells before busbars are attached to each terminal. [Figure 4] This is a perspective view showing the busbar. [Figure 5] This perspective view shows a modified example in which the terminals of adjacent battery cells are superimposed in the height direction of the battery pack. [Figure 6] This is a perspective view showing a modified example where the terminals of adjacent battery cells are butted together. [Figure 7] This is a perspective view showing the main part of the battery pack related to the comparative example. [Figure 8]In the comparative example, it is a perspective view showing a state in which a bus bar is pressed against a terminal of a battery cell by a pressing jig.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the battery pack 10 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6. Note that in each figure, some reference numerals may be omitted for the sake of clarity of the drawing.

[0017] (Configuration) As shown in FIG. 1, the battery pack 10 according to the present embodiment is mounted on vehicles such as electric vehicles, hybrid vehicles, fuel cell vehicles, and solar cars, and includes a battery case 12 and a plurality (here, a large number) of battery cells 16 housed in the battery case 12. The battery case 12 has a flat box-shaped case body 14 that is open on the upper side and a cover (not shown) that closes the opening of the case body 14. The case body 14 and the cover are rectangular in plan view. The arrows X, Y, and Z appropriately shown in each figure indicate the longitudinal direction, width direction, and height direction (vertical direction) of the battery pack 10 and the battery case 12, respectively.

[0018] As shown in FIGS. 1 to 3, the battery cell 16 is, for example, a lithium-ion secondary battery cell and has a rectangular parallelepiped cell body 18. Inside the battery case 12, a large number of battery cells 16 are housed side by side in the longitudinal direction and width direction of the battery case 12. Each battery cell 16 is arranged in the battery case 12 with the longitudinal direction of the battery case 12 as the longitudinal direction, the height direction of the battery case 12 as the width direction, and the width direction of the battery case 12 as the thickness direction.

[0019] A positive electrode terminal 20 (not shown in FIG. 1) is provided on one end face in the longitudinal direction of the cell body 18, and a negative electrode terminal 20 (not shown in FIG. 1) is provided on the other end face in the longitudinal direction of the cell body 18. External terminals 22 are fixed to the positive and negative electrode terminals 20, respectively. The external terminal 22 corresponds to the "terminal" in the present invention.

[0020] The electrode terminal 20 is manufactured by press-forming, for example, a plate material made of an aluminum alloy, and has a long plate shape. The electrode terminal 20 is arranged in a posture such that the longitudinal direction of the cell body 18 is the plate thickness direction and the width direction of the cell body 18 (the height direction of the battery case 12) is the longitudinal direction.

[0021] The external terminal 22 is manufactured by press-forming, for example, a plate material made of an aluminum alloy, and has a plate shape with a substantially Z-shaped cross-section (substantially crank-shaped cross-section). The external terminal 22 includes a fixing portion 22A that is overlapped with the upper portion of the electrode terminal 20 in the plate thickness direction, a curved portion 22B that extends from the upper end portion of the fixing portion 22A on the side opposite to the cell body 18 and upward in the height direction of the battery case 12, and a flat plate portion 22C that extends upward in the height direction of the battery case 12 from the tip portion of the curved portion 22B.

[0022] The fixing portion 22A and the flat plate portion 22C have a flat plate shape with the longitudinal direction of the battery case 12 as the plate thickness direction. The curved portion 22B is curved in an arc shape when viewed from the width direction of the battery case 12. The fixing portion 22A is fixed to the electrode terminal 20, for example, by welding. Note that each electrode terminal 20 and each external terminal 22 may be integrally manufactured.

[0023] The battery cells 16 adjacent to each other in the longitudinal direction of the battery case 12 are arranged in a state where the flat plate portions 22C of the external terminals 22 overlap each other in the longitudinal direction of the battery case 12. The dimensional error between adjacent battery cells 16 as described above is configured to be absorbed by the elastic deformation of the curved portion 22B of the external terminal 22. As shown in FIG. 2, the flat plate portions 22C overlapped as described above are sandwiched by clip-shaped bus bars 24 (not shown in FIG. 1). Note that in FIG. 2, only one set of external terminals 22 and only one bus bar 24 are shown for the sake of easy viewing of the drawing.

[0024] The busbar 24 is manufactured, for example, by bending a sheet of aluminum alloy. As shown in Figure 4, the busbar 24 integrally has a pair of elongated plate-shaped clamping portions 24A that face each other in the thickness direction, and a connecting portion 24B that connects one end of the pair of clamping portions 24A in the longitudinal direction, and has a substantially U-shaped cross-section.

[0025] The distance between the pair of clamping portions 24A is set to be equivalent to the thickness of the pair of flat plate portions 22C that are stacked as described above. These pairs of flat plate portions 22C are positioned between the pair of clamping portions 24A and are clamped in the thickness direction by the pair of clamping portions 24A. The pair of clamping portions 24A and the pair of flat plate portions 22C are welded (joined; fixed) at the welded portion W shown in Figure 2. The welding method for this welded portion W is, for example, laser welding. As a result, the positive electrode terminal 20 provided on one of the adjacent battery cells 16 and the negative electrode terminal 20 provided on the other are electrically connected via a pair of external terminals 22.

[0026] As shown in Figure 1, on both sides in the longitudinal direction of the battery case 12, a positive electrode terminal 20 (not shown in Figure 1) provided on one of the battery cells 16 adjacent in the width direction of the battery case 12 and a negative electrode terminal 20 (not shown in Figure 1) provided on the other are electrically connected via external terminals 22 and busbars 26.

[0027] It should be noted that the configuration is not limited to the one described above, in which a pair of flat plates 22C are superimposed in the longitudinal direction of the battery case 12. For example, as shown in the first modified example in Figure 5, a pair of flat plates 28B may be superimposed in the height direction of the battery case 12, or a pair of flat plates 30B may be abutted together in the longitudinal direction of the battery case 12, as shown in the second modified example in Figure 6.

[0028] In the first modified example shown in Figure 5, the external terminal 28 is composed of a fixed portion 28A superimposed on the upper part of the electrode terminal 20 in the thickness direction, and a flat plate portion 28B extending from the upper end of the fixed portion 28A in the direction opposite to the cell body 18, and has a roughly L-shaped cross-section. Battery cells 16 adjacent to each other in the longitudinal direction of the battery case 12 are sandwiched between busbars 24 with the flat plate portions 28B of the external terminals 28 superimposed on each other in the height direction of the battery case 12, and are welded to the busbars 24 at the welded portion W. Note that in Figure 5, for the sake of clarity, only one set of external terminals 28 and only one busbar 24 are shown.

[0029] In the second modified example shown in Figure 6, the external terminal 30 has a roughly L-shaped cross-section, similar to the first modified example, and is composed of a fixed portion 30A and a flat plate portion 30B. Battery cells 16 adjacent to each other in the longitudinal direction of the battery case 12 are sandwiched between busbars 24 with the flat plate portions 30B of the external terminals 30 abutting against each other in the longitudinal direction of the battery case 12, and are welded to the busbars 24 at two welded joints W aligned in the longitudinal direction of the battery case 12. Note that in Figure 6, for the sake of clarity, only one set of external terminals 30 and only one busbar 24 are shown.

[0030] Next, the operation and effects of this embodiment will be described. In the battery pack 10 with the above configuration, each of the multiple battery cells 16 housed side by side in the battery case 12 is provided with an external terminal 22 having a flat plate portion 22C. The flat plate portions 22C of adjacent battery cells 16 in the longitudinal direction of the battery case 12 are clamped by a clip-shaped busbar 24 and welded to the busbar 24. In this way, by clamping the flat plate portion 22C of each external terminal 22 by the busbar 24, welding can be performed while maintaining a constant gap between each flat plate portion 22C and the busbar 24, and welding can be performed in confined spaces. Therefore, the external terminal 22 and the busbar 24 can be properly fixed in a space-saving manner.

[0031] The effects described above will be further explained using comparative examples shown in Figures 7 and 8. In the battery pack 40 according to this comparative example, as shown in Figure 7, a large number of battery cells 44 are housed in a battery case 42. An electrode terminal (not shown) is provided at the upper end of each battery cell 44, and the electrode terminals of adjacent battery cells 44 are connected by a busbar 46. As shown in Figure 8, the busbar 46 is pressed against the electrode terminal using a pressing jig 48, and the gap between the electrode terminal and the busbar 46 is measured. If this gap is within the acceptable range, the electrode terminal and the busbar 46 are welded together.

[0032] In a configuration like the one in this comparative example, space is required in the height direction of the battery pack 40. As a result, it becomes difficult to miniaturize the battery pack 40 in the height direction or to improve the stacking efficiency of the battery cells 44 within the battery pack 40. However, in this embodiment, the pressing jig 48 and gap measurement described above are unnecessary, making it possible to miniaturize the battery pack 10 and improve the stacking efficiency of the battery cells 16. Moreover, since the terminals and busbars are not fixed by crimping alone, it is possible to prevent the resistance value from increasing due to oxidation of the interface due to aging.

[0033] Furthermore, in a configuration where the flat plate portions 22C and 28B of adjacent battery cells 16 are overlapped and sandwiched between the busbar 24 and welded, as in this embodiment and the first modified example shown in Figure 5, it is easier to reduce the space required for arranging the external terminals 22 in the longitudinal direction of the battery case 12 compared to the second modified example shown in Figure 6. On the other hand, in a configuration where the flat plate portions 30B of the external terminals 30 are abutted against each other and sandwiched between the busbar 24 and welded, each flat plate portion 30B is welded to the busbar 24 at two welds W, so each flat plate portion 30B can be welded equally to the busbar 24.

[0034] Although the present invention has been described above with reference to embodiments, the present invention can be implemented with various modifications without departing from its spirit. Furthermore, it goes without saying that the scope of the present invention is not limited to the above embodiments. [Explanation of Symbols]

[0035] 10 battery packs 12 Battery Case 16 battery cells 22 External terminals (terminals) 22C Flat plate part 24 Bus Bar 28 External terminals (terminals) 28B Flat plate part 30 External terminals (terminals) 30B Flat plate part

Claims

1. A pair of terminals, each having a flat plate-shaped portion, A clip-shaped busbar that clamps each of the aforementioned flat plate portions and is welded to each of the aforementioned flat plate portions, A fixing structure for terminals and busbars equipped with [specific features / features].

2. The terminal and busbar fixing structure according to claim 1, wherein the flat plate portions are abutted against each other and sandwiched between the busbar.

3. The terminal and busbar fixing structure according to claim 1, wherein the flat plate portions are overlapped and sandwiched between the busbar.

4. Battery case and A plurality of battery cells are housed side by side within the aforementioned battery case, each having terminals that are flat and plate-shaped, Multiple clip-shaped busbars that clamp each of the flat plate portions of adjacent battery cells and are welded to each of the flat plate portions, A battery pack is included.

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