JP7559724B2 - Battery pack - Google Patents

Description

This disclosure relates to a battery pack.

Conventionally, battery packs including multiple batteries have been proposed (see Patent Document 1). In such battery packs, conductive bus bars are used to electrically connect the positive electrodes or negative electrodes of the multiple batteries. For example, in the battery pack of Patent Document 1, the batteries are arranged side by side with their axial directions aligned, and the positive electrode bus bars and the negative electrode bus bars are both concentrated on one pole side of each battery.

International Publication No. 2019/058938

In battery packs in which bus bars are concentrated on one pole side, as in Patent Document 1, a three-layer structure consisting of a positive bus bar, an insulating layer, and a negative bus bar may be adopted. In this case, a thickness of three layers is required, which increases the size of the battery pack and makes it difficult to meet the demand for miniaturization. For this reason, technology that can prevent the battery pack from becoming larger is desired.

This disclosure has been made to solve at least some of the problems described above, and can be realized in the following forms:

(1) According to one aspect of the present disclosure, there is provided a battery pack comprising: a plurality of batteries arranged with an axial direction aligned; and a busbar module arranged to be stacked in the axial direction with respect to the plurality of batteries and electrically connected to the plurality of batteries, the busbar module having a positive busbar electrically connected to each of the positive electrodes of the plurality of batteries, a negative busbar electrically connected to each of the negative electrodes of the plurality of batteries, and an insulator interposed between the positive busbar and the negative busbar, wherein each of the plurality of batteries has a positive electrode located at a center at an end in the axial direction and a negative electrode located at an outer periphery at the end, and the positive busbar and the negative busbar overlap each other in the axial direction. the positive electrode busbar is in contact with the positive electrode at least in the orthogonal direction, the negative electrode busbar is in contact with the negative electrode in the axial direction, the insulator has a first contact portion that contacts the positive electrode busbar in the axial direction, a second contact portion that contacts the positive electrode busbar in the orthogonal direction, and a third contact portion that contacts the negative electrode busbar in the orthogonal direction, and the busbar module has a first two-layer structure portion in which the positive electrode busbar and the insulator overlap in the axial direction, and a single-layer structure portion adjacent to the first two-layer structure portion in the orthogonal direction and in which only the insulator is arranged in the axial direction. According to this embodiment, the positive busbar and the negative busbar are arranged at a predetermined interval in the orthogonal direction perpendicular to the axial direction so as not to overlap each other in the axial direction, and the busbar module has a first two-layer structure portion in which the positive busbar and the insulator overlap in the axial direction, and a single-layer structure portion adjacent to the first two-layer structure portion in the orthogonal direction and in which only the insulator is arranged in the axial direction. This prevents the positive busbar, negative busbar, and insulator from overlapping in the axial direction, thereby reducing the axial thickness and preventing the battery pack from becoming larger.
(2) In the battery pack of the above aspect, the insulator may further include a fourth contact portion that contacts the negative bus bar in the axial direction, and the bus bar module may further include a second two-layer structure portion adjacent to the one-layer structure portion in the orthogonal direction, in which the negative bus bar and the insulator overlap in the axial direction. This aspect can improve insulation between the positive bus bar and the negative bus bar.
(3) In the battery pack of the above aspect, the positive electrode bus bar may be in contact with the positive electrode in the axial direction in addition to the orthogonal direction. According to this aspect, it is possible to increase the contact area between the positive electrode bus bar and the positive electrode, thereby improving electrical conductivity.
(4) In the battery pack of the above aspect, the positive electrode and the positive electrode bus bar may be connected by wire bonding. According to this aspect, a strong electrical connection between the positive electrode and the positive electrode bus bar can be realized by a simple method.
(5) In the battery pack according to the above aspect (3), the positive electrode and the positive electrode bus bar may be welded to each other in the axial direction. According to this aspect, the connection between the positive electrode and the positive electrode bus bar can be realized with a simpler structure.
(6) In the battery pack according to the above aspect, the negative electrode and the negative electrode bus bar may be electrically connected to each other in the axial direction by welding. According to this aspect, the connection between the negative electrode and the negative electrode bus bar can be realized with a simpler structure.
(7) In the battery pack according to any one of the above (1) to (5), the negative electrode and the negative electrode bus bar may be electrically connected to each other in the axial direction by wire bonding. According to this embodiment, the connection between the negative electrode and the negative electrode bus bar can be realized with a simpler structure.

The present disclosure can also be realized in various forms other than a battery pack. For example, it can be realized in the form of a manufacturing method for a battery pack, etc.

1 is an exploded perspective view showing a battery pack according to an embodiment of the present disclosure; FIG. 2 is an exploded perspective view of the bus bar module. FIG. 3 is a plan view of the bus bar shown in FIG. 2 . 4 is a cross-sectional view taken along line AA in FIG. 3, showing the area surrounding one of the three batteries. FIG. 11 is an exploded perspective view of a battery pack according to a second embodiment. FIG. 11 is an exploded perspective view of a bus bar module according to a second embodiment. FIG. 6 is a plan view of the bus bar module shown in FIG. 5 . 8 is a cross-sectional view showing a region near one of the three batteries, taken along line GG in FIG. 7, to which a pressing plate and a pressing load adjusting member are added. 13 is a schematic diagram for explaining a pressing load adjusting member attached to a pressing plate portion. FIG. FIG. 11 is a cross-sectional view for explaining a battery pack according to a third embodiment. 13 is a schematic diagram for explaining a pressing load adjusting member attached to a pressing plate portion in a battery pack of a third embodiment. FIG. FIG. 13 is a cross-sectional view for explaining a battery pack according to a fourth embodiment. FIG. 13 is a cross-sectional view for explaining a battery pack according to a fifth embodiment. FIG. 13 is a schematic diagram for explaining a pressing load adjusting member attached to a pressing plate portion in a battery pack of another embodiment (F2). FIG. 13 is a schematic diagram for explaining a pressing load adjusting member attached to a pressing plate portion in a battery pack of another embodiment (F3).

A. First embodiment:
A1. Overview of the battery pack:
Fig. 1 is an exploded perspective view of a battery pack 100 according to an embodiment of the present disclosure. As shown in Fig. 1, the battery pack 100 includes a battery array group 20, a bus bar module 10, an insulating member 30, a lower case 40, an upper case 50, and voltages Vt1 to Vt4. The battery pack 100 supplies power to an external terminal (not shown) from a plurality of batteries Bt connected in parallel and in series by the bus bar module 10. The batteries Bt are general-purpose cylindrical batteries, and for example, lithium ion batteries used as power sources for automobiles can be used.

Figure 1 shows X, Y and Z axes which are mutually orthogonal. The X-axis direction is also called the column direction of the battery. The Y-axis direction is a direction perpendicular to the column direction. The Z-axis direction is a direction parallel to the side of the battery, and is also called the axial direction of the battery.

The battery array group 20 is a combination of a plurality of batteries Bt arranged in the same axial direction. As shown in FIG. 1, the battery array group 20 has a plurality of batteries Bt arranged in the X direction. Here, as shown in the figure, the battery array group 20 has three battery arrays arranged. The number of battery arrays in the battery array group 20 is not limited to three as long as it does not impair the effects of this embodiment. Each battery Bt is a cylindrical battery, and a positive electrode Btp is formed at one end in the axial direction. The positive electrode Btp is provided protruding from the center of one end of the battery Bt. In this embodiment, at one end of the battery Bt where the positive electrode Btp is formed, a negative electrode Btn is also formed on the outer periphery. More specifically, a negative electrode is formed so as to cover the entire other end opposite the one end where the positive electrode Btp is formed, the entire side surface of the battery Bt from the other end, and the outer periphery of the one end in a continuous manner. The negative electrode on the side of the battery Bt is covered with an insulating member such as a resin. The orientation of each battery Bt shown in the figure is the same for all of the battery string group 20. In this embodiment, the multiple batteries Bt have a configuration in which multiple battery sets, each consisting of two batteries Bt connected in parallel to each other, are connected in series. Each battery set consists of two batteries Bt arranged in the column direction (X-axis direction). Two battery sets BtA and BtB are illustrated in FIG. 1.

As shown in FIG. 1, the busbar module 10 is arranged in an axial direction so as to be overlapped with the batteries Bt. The busbar module 10 realizes the electrical connection (parallel connection) between the two batteries Bt in the battery set described above, and realizes the electrical connection (series connection) between the multiple battery sets. FIG. 2 is an exploded perspective view of the busbar module 10. As shown in FIG. 2, the busbar module 10 includes a busbar 11 and an insulator 12. The busbar 11 is formed of a metal thin plate. The busbar module 10 is constructed by embedding the busbar 11 in the insulator 12 made of a resin material by insert molding, post-bonding, post-welding, claw fitting, or the like. Note that in FIG. 2, the busbar 11 is shown above the insulator 12 for convenience of illustration, but when the busbar module 10 is formed by insert molding, for example, the upper and lower positional relationship in the axial direction between the busbar 11 and the insulator 12 will differ depending on the position of the region in the busbar module 10.

Figure 3 is a plan view of the busbar 11 shown in Figure 2. The busbar 11 is composed of a number of positive busbars PB and a number of negative busbars NB. The positive busbars PB and the negative busbars NB are both made by pressing a thin metal plate. The thickness of the busbars 11 (the positive busbars PB and the negative busbars NB) is 0.2 to 1.2 mm (millimeters). Note that the thickness of the busbars 11 is not limited to 0.2 to 1.2 mm, and may be any thickness that provides the effect of this embodiment.

The positive bus bar PB connects the positive electrodes Btp of the two batteries Bt that make up the battery set in parallel. The positive bus bar PB has two openings into which the positive terminals of the two batteries Bt are inserted. The positive bus bar PB has a portion that surrounds each of the two openings, a portion that connects the two openings, and a protruding portion for contacting the negative bus bar NB of the adjacent battery set. In this embodiment, the "protruding portion" protrudes parallel to the X-Y plane.

The negative busbar NB connects the negative electrodes Btn of the two batteries Bt that make up the battery set in parallel. The negative busbar NB has a portion that surrounds the positive busbar PB that surrounds the two openings described above, with a gap in the axial direction and in the orthogonal direction (hereinafter simply referred to as the "orthogonal direction") that is orthogonal to the axial direction. The negative busbar NB that constitutes the overall negative electrode electrode TN1 described below has a protruding portion, similar to the positive busbar PB. The "protruding portion" of the negative busbar NB protrudes parallel to the X-Y plane, similar to the positive busbar PB.

Two adjacent battery sets are connected in series by arranging the positive bus bar PB of one battery set in contact with the negative bus bar NB of the other battery set. Of all the battery sets connected in series in this way, the two battery sets at the ends of the series connection, which are located on the rightmost side in FIG. 3, are provided with a general electrode. Specifically, a general positive electrode TP1 is provided on the positive bus bar PB of the battery set at one end, and a general negative electrode TN1 is provided on the negative bus bar NB of the battery set at the other end. The general positive electrode TP1 and the general negative electrode TN1 function as terminals for extracting the electrical output of the battery pack 100.

The insulator 12 shown in FIG. 2 secures electrical insulation between the multiple bus bars by embedding the positive bus bar PB and the negative bus bar NB in a resin material. The resin material for the insulator 12 can be a polyester resin or a polyester elastomer, such as polybutylene terephthalate [PBT] or a PBT-based polyester elastomer.

Figure 4 is a cross-sectional view taken along line A-A in Figure 3, showing the vicinity region R1 of one battery Btc2 of the three batteries Btc1 to Btc3. Note that insulators are omitted from Figure 3 for ease of explanation and illustration, but the cross-sectional view in Figure 4 shows insulator Ju. The positive bus bar PB is electrically connected to the positive electrodes Btp of the two batteries Bt that make up the battery set. The negative bus bar NB is electrically connected to the negative electrodes N1 of the multiple batteries Bt. The insulator 12 shown in Figure 2 is interposed between the positive bus bar PB and the negative bus bar NB.

The insulating member 30 shown in FIG. 1 is a thin plate-like member made of an insulating material, and is disposed at the boundary between adjacent battery sets to function as an insulating wall. Therefore, the battery array group 20 is divided into each battery set by the insulating member 30. As shown in FIG. 1, the lower case 40 holds the battery array group 20, to which the bus bar module 10 and insulating member 30 are assembled, at the bottom in the +Z direction. The upper case 50 covers the battery array group 20, to which the bus bar module 10 and insulating member 30 are assembled, from the -Z direction. The bolts Vt1 to Vt4 are attached to four holes provided in the lower case 40 to fix the lower case 40 to the upper case 50.

As shown in FIG. 4, the positive busbar PB is disposed at a position where it contacts the positive electrode Btp in the orthogonal direction CD perpendicular to the axial direction AD. The orthogonal direction can also be said to be the radial direction of a circle formed by the outer edge of the battery Bt in a plan view. An insulator Ju is disposed between the positive busbar PB and the battery Btc2 in the axial direction. As shown in FIG. 4, the insulator Ju has a first contact portion Rc1 that contacts the positive busbar PB in the axial direction. The busbar module 10 has a first two-layer structure portion 21S in which the positive busbar PB and the insulator Ju overlap in the axial direction. In the positive electrode Btp, the surface that contacts the positive busbar PB forms an inclined surface. As shown in FIG. 4, the inclined surface and the axial end surface of the positive electrode Btp form an obtuse angle.

The positive busbar PB and the negative busbar NB are arranged at a predetermined interval dw in the orthogonal direction so as not to overlap each other in the axial direction. In this embodiment, the predetermined interval dw in the orthogonal direction is 2 mm. Note that the predetermined interval dw is not limited to 2 mm, and may be any interval that provides the effect of this embodiment. At the predetermined interval dw, an insulator Ju is arranged in the axial direction AD. The insulator Ju has a second contact portion Rc2 that contacts the positive busbar PB in the orthogonal direction and a third contact portion Rc3 that contacts the negative busbar NB in the orthogonal direction. The busbar module 10 has a first single-layer structure portion 11S in which only the insulator Ju is arranged in the axial direction adjacent to the first two-layer structure portion 21S described above in the orthogonal direction.

As shown in FIG. 4, the negative busbar NB is disposed at a position where it contacts the negative electrode N1 in the axial direction. In this embodiment, the axial thickness of the negative busbar NB is 0.8 mm. The negative busbar NB contacts the insulator Ju on a part of the surface opposite to the surface facing the negative electrode N1. In this embodiment, the axial thickness of the insulator Ju is 0.2 mm. The insulator Ju has a fourth contact portion Rc4 that contacts the negative busbar NB in the axial direction. The busbar module 10 has a second two-layer structure portion 22S in which the insulator Ju and the negative busbar NB overlap in the axial direction. The second two-layer structure portion 22S is adjacent to the first one-layer structure portion 11S described above in the orthogonal direction CD. The busbar module 10 also has a second one-layer structure portion 12S in which only the negative busbar NB is disposed in the axial direction adjacent to the second two-layer structure portion 22S described above in the orthogonal direction. The axial thickness of the negative bus bar NB and the axial thickness of the insulator Ju that is in axial contact with the negative bus bar NB are not limited to 0.8 mm and 0.2 mm, respectively, and may be any thickness as long as the effect of this embodiment is achieved.

Since the positive busbar PB and the negative busbar NB do not overlap in the axial direction, an increase in the axial thickness of the busbar module 10 is suppressed, and an increase in the size of the battery pack 100 is suppressed. In addition, a part of the surface of the negative busbar NB opposite the surface facing the negative electrode N1 is in contact with the insulator Ju. On the other hand, the other part of this surface corresponds to the end surface of the negative busbar NB in the second single-layer structure portion 12S described above, and is exposed. This increases the heat dissipation area of the battery, improving heat dissipation performance.

As shown in FIG. 4, the positive electrode Btp and the positive electrode bus bar PB are connected by wire bonding using the wiring WB. This makes it possible to realize a strong electrical connection between the positive electrode Btp and the positive electrode bus bar PB in a simple manner.

According to the battery pack 100 of the first embodiment described above, the positive bus bar PB and the negative bus bar NB are arranged at a predetermined distance dw in the orthogonal direction CD, and the positive bus bar PB and the negative bus bar NB have an insulator Ju that contacts them in the axial direction AD. Since the positive bus bar PB and the negative bus bar NB do not overlap in the axial direction AD, an increase in the thickness of the bus bar module 10 in the axial direction AD can be suppressed, and an increase in the size of the battery pack 100 can be suppressed.

The positive bus bar PB is also positioned in contact with the positive electrode Btp in the perpendicular direction CD, and has an insulator Ju between it and the battery Bt that contacts the battery Bt in the axial direction AD, preventing a short circuit between the positive bus bar PB and the negative electrode N1.

The negative busbar NB is disposed at a position in contact with the negative electrode N1 in the axial direction AD, and has an insulator Ju in contact with the axial direction AD on a portion of the surface opposite the surface facing the negative electrode N1. This can better prevent short circuits between the positive busbar PB and the negative busbar NB. Also, a portion of the surface of the negative busbar NB opposite the surface facing the negative electrode N1 is in contact with the insulator Ju, but the other portions of this surface are exposed. This increases the area for dissipating heat from the battery, improving heat dissipation performance.

The positive electrode Btp and the positive electrode bus bar PB are connected via wiring WB formed by wire bonding. This makes it possible to achieve a strong electrical connection between the positive electrode P1 and the positive electrode bus bar PB in a simple manner.

B. Second embodiment:
B1. Overview of the battery pack:
Fig. 5 is an exploded perspective view of a battery pack 100A according to a second embodiment. As shown in Fig. 5, the battery pack 100A according to the second embodiment differs from the battery pack 100 according to the first embodiment in that the battery pack 100A according to the second embodiment includes a pressing plate portion Ue, a pressing load adjusting member Pu, and a bus bar module 10A instead of the bus bar module 10. Other than this, the configuration of the battery pack 100A according to the second embodiment is the same as the configuration of the battery pack 100 according to the first embodiment, and therefore the same components are denoted by the same reference numerals and description thereof will be omitted.

The pressing plate Ue serves to press the busbar module 10A against the battery array group 20. As shown in FIG. 5, the pressing plate Ue is formed of a rectangular parallelepiped thin metal plate. The metal is, for example, aluminum. Note that the pressing plate Ue is not limited to aluminum and may be formed of other metals as long as the effects of this embodiment are achieved. Four holes are provided at the four corners of the pressing plate Ue. Bolts Vt5 to Vt8 are attached to the four holes, and the pressing plate Ue is attached to the upper case 50. Note that the pressing plate Ue may be formed of resin as long as the effects of this embodiment are achieved.

The pressing load adjustment member Pu adjusts the load pressing the busbar module 10A against the battery array group 20. The pressing load adjustment member Pu is attached to the surface of the pressing plate portion Ue facing the busbar module 10A. FIG. 9 is a schematic diagram for explaining the pressing load adjustment member Pu attached to the pressing plate portion Ue. The pressing load adjustment member Pu is made of an elastic body, and is formed of rubber such as EPDM (ethylene propylene diene rubber). Since the pressing load adjustment member Pu is an elastic body, even if there is variation in the height of the battery Bt or the thickness of the busbar 11, such variation can be absorbed and each busbar module 10 can be pressed against the battery Bt with an appropriate force. Note that the pressing load adjustment member Pu is not limited to rubber such as EPDM, but may be a thermoplastic elastomer combining polypropylene and EPDM, or may be formed of an elastic body of any other type of material as long as it achieves the effect of the present embodiment. As shown in FIG. 9, the pressing load adjustment member Pu is press-fitted into a hole Uh formed in the end face of the pressing plate portion Ue that is attached to the upper case 50.

Figure 6 is an exploded perspective view of a busbar module 10A according to a second embodiment. As shown in Figure 6, the busbar module 10A includes a busbar 11 and an insulator 12A. Figure 7 is a plan view of the busbar module 10A shown in Figure 5. In Figure 7, the negative busbar NB is not shown because it is covered by the insulator 12A.

Figure 8 is a cross-sectional view showing the vicinity region R2 of one battery Btc2A among the three batteries Btc1A to Btc3A, taken along line G-G in Figure 7, to which a pressing plate portion Ue and a pressing load adjustment member Pu have been added. First, differences between the busbar module 10A and the busbar module 10 will be described. As shown in Figure 8, the busbar module 10A is different from the busbar module 10 in that the entire surface of the negative busbar NB opposite to the surface facing the negative electrode N1 is in contact with the insulator Ju, and that the positive electrode Btp and the positive busbar PB are not provided with wiring WB for connection by wire bonding. The busbar module 10A has a third two-layer structure portion 23S in which the insulator Ju and the negative busbar NB overlap in the axial direction, instead of the second two-layer structure portion 22S. The busbar module 10A has an insulator Ju that contacts the entire end surface of the negative busbar NB. The third two-layer structure portion 23S is adjacent to the first one-layer structure portion 11S in the perpendicular direction CD. In the battery pack 100A of the second embodiment, instead of the second two-layer structure portion 22S, the battery pack 100A has a third two-layer structure portion 23S that contacts the insulator Ju over the entire end surface of the negative busbar NB, improving insulation. The negative busbar NB and the negative electrode N1 may be electrically connected in the axial direction AD by welding or wire bonding.

As described above, the battery pack 100A is different from the battery pack 100 in that it includes a pressing plate portion Ue and a number of pressing load adjustment members Pu. As shown in FIG. 8, the pressing plate portion Ue is disposed away from the busbar module 10A in the axial direction AD. Note that FIG. 8 does not show that each pressing load adjustment member Pu is pressed into a hole provided in the pressing plate portion Ue. The pressing load adjustment members Pu in FIG. 8 and FIG. 9 are the same, but FIG. 8 shows the shape of a trapezoid that is inverted 180 degrees more clearly. In this embodiment, as shown in FIG. 8 and FIG. 9, the contact area of the busbar module 10A side grounding portion of the pressing load adjustment member Pu is reduced, and the pressure value to the local area to which the pressing pressure is applied is increased.

The battery pack 100A of the second embodiment described above has the same effect as the battery pack 100 of the first embodiment. In addition, the battery pack 100A of the second embodiment has an insulator Ju in contact with the axial direction on the entire surface opposite the surface facing the negative electrode N1, which enhances the prevention of short circuits between the positive electrode bus bar PB and the negative electrode bus bar NB.

The battery pack 100A of the second embodiment is also equipped with a pressing plate portion Ue and a pressing load adjustment member Pu, so that the bus bar module 10A can be pressed against the battery Bt. This eliminates the need for electrical connection processing by wire bonding, and allows for improved production efficiency compared to the battery pack 100 of the first embodiment.

C. Third embodiment:
C1. Overview of battery pack configuration:
FIG. 10 is a cross-sectional view for explaining the battery pack 100B of the third embodiment. FIG. 11 is a schematic diagram for explaining the pressing load adjusting member PuB attached to the pressing plate portion Ue in the battery pack 100B of the third embodiment. In the battery pack 100B of the third embodiment, the difference from the battery pack 100A of the second embodiment is that, as shown in FIG. 10 and FIG. 11, a large number of pressing load adjusting members PuB are connected to each other in the orthogonal direction CD, and the positive electrode bus bar PB is further arranged at a position in contact with the end face of the positive electrode Btp in the axial direction. The other configuration of the battery pack 100B of the third embodiment is the same as that of the battery pack 100A of the second embodiment, so the same reference numerals are used for the same configurations and the description will be omitted. The battery pack 100B of the third embodiment has the same effect as the battery pack 100A of the second embodiment.

Furthermore, in the battery pack 100B of the third embodiment, in addition to the pressing load adjustment member Pu of the battery pack 100A of the second embodiment, a large number of pressing load adjustment members PuB are bonded to each other with a resin material. This makes it easy to assemble a large number of pressing load adjustment members PuB to the pressing plate portion Ue. In addition, the contact area between the pressing load adjustment member PuB and the pressing plate portion Ue is enlarged, improving the bonding strength between the two. In addition, the positive electrode bus bar PB and the positive electrode Btp can be bonded by welding instead of bonding via the wiring WB by wire bonding. Therefore, the connection between the positive electrode bus bar PB and the positive electrode Btp can be realized with a simpler structure. In addition, the area of the pressing load adjustment member PuB in FIG. 10 that presses the positive electrode bus bar PB may be an area that overlaps with the positive electrode Btp in the axial direction. By doing this, the pressing plate portion Ue presses the portion of the positive bus bar PB that faces the positive electrode Btp in the axial direction, so that the positive bus bar PB and the positive electrode Btp can be in stronger contact with each other.

D. Fourth embodiment:
D1. Overview of battery pack configuration:
Fig. 12 is a cross-sectional view for explaining a battery pack 100E of the fourth embodiment. As shown in Fig. 12, the battery pack 100E of the fourth embodiment is different from the battery pack 100A of the second embodiment shown in Fig. 8 in that it includes a conductive elastic member CM1. Other than this, the configuration of the battery pack 100E of the fourth embodiment is the same as the configuration of the battery pack 100A of the second embodiment, so the same components are denoted by the same reference numerals and description thereof will be omitted.

The conductive elastic member CM1 plays a role in absorbing the variation in the position and dimensions of the battery Bt in the battery array group 20 shown in FIG. 1 and FIG. 5. As shown in FIG. 12, the conductive elastic member CM1 is formed in a shape in which one straight part of an L-shape is bent toward the positive electrode Btp side in a cross-sectional view. The conductive elastic member CM1 is formed of a porous elastic member made of metal. Such a metal is, for example, aluminum. Note that the conductive elastic member CM1 is not limited to aluminum, and may be formed of any other conductive elastic member, as long as the effect of this embodiment is achieved. In addition, the conductive elastic member CM1 is a member having a larger compression ratio than the positive electrode bus bar PB. In this embodiment, the compression ratio of the conductive elastic member CM1 is 50% or more. Note that the compression ratio of the conductive elastic member CM1 is not limited to 50% or more, and may be any compression ratio, as long as the effect of this embodiment is achieved. In addition, the shape of the conductive elastic member CM1 is not limited to a shape in which one straight part of an L shape is bent toward the positive electrode Btp side in a cross-sectional view, but may be an L shape, or may be any shape as long as it achieves the effect of this embodiment. In addition, the conductive elastic member CM1 does not have to be formed of a porous material as long as it has elasticity and conductivity and has a larger compressibility than the positive electrode bus bar PB.

As shown in FIG. 12, the conductive elastic member CM1 is disposed between the positive electrode Btp and the busbar module 10E in the orthogonal direction CD. The conductive elastic member CM1 has a fifth contact portion Rc5 that contacts the positive electrode Btp in the orthogonal direction CD. The conductive elastic member CM1 also has a sixth contact portion Rc6 that contacts the positive electrode busbar PB in the orthogonal direction CD. The conductive elastic member CM1 is in contact with the insulator Ju in the orthogonal direction CD. The conductive elastic member CM1 also has a seventh contact portion Rc7 that contacts the battery Btc2A in the axial direction AD. The conductive elastic member CM1 also has an eighth contact portion Rc8 that contacts the positive electrode busbar PB in the axial direction AD. As shown in FIG. 12, the end of the insulator Ju on the positive electrode Btp side in the orthogonal direction CD is recessed to the negative electrode N1 side. The recessed area is the area sandwiched between the seventh contact portion Rc7 and the eighth contact portion Rc8. In addition, the end of the conductive elastic member CM1 in the axial direction AD does not protrude from the end face of the bus bar module 10E in the axial direction AD. The height of the conductive elastic member CM1 in the axial direction AD is the same as the height of the bus bar module 10E in the axial direction AD. There is no area in the axial direction AD where there are three layers among the positive bus bar PB, the insulator Ju, and the conductive elastic member CM1. Therefore, even if the conductive elastic member CM1 is arranged, the thickness of the battery pack 100E in the axial direction AD is the same as that of the battery pack 100A of the second embodiment, and the size of the battery pack 100E can be suppressed.

In addition, even if there is variation in the position and dimensions between the batteries Bt, the conductive elastic member CM1, which has elasticity and is interposed between the positive bus bar PB and the positive electrode Btp in the perpendicular direction CD, deforms to follow the shape of the positive electrode Btp side, and thus absorbs such variation. In other words, the conductive elastic member CM1 functions like a sponge or cushion. Therefore, the variation in the position and dimensions of the batteries Bt is absorbed, and the decrease in conductivity is suppressed.

Furthermore, in the battery pack 100E of the fourth embodiment, the conductive elastic member CM1 further has a seventh contact portion that contacts the battery Btc2A in the axial direction AD, and an eighth contact portion that contacts the positive bus bar PB in the axial direction AD, so that the contact cross-sectional area between the conductive elastic member CM1 and the positive bus bar PB can be increased, improving conductivity. In addition, the conductive elastic member CM1 has a shape sandwiched between the seventh contact portion Rc7 and the eighth contact portion Rc8, so that the shape is well-fitted and easy to manufacture.

In the battery pack 100E of the fourth embodiment, the thickness of the conductive elastic member CM1, the porous material of the conductive elastic member CM1, the porous fiber diameter, the porosity ratio, the distance between the positive bus bar PB and the positive electrode Btp, etc. are optimized to better absorb the variation in position and size between the batteries Bt. During the resin molding process in which the positive bus bar PB and the negative bus bar NB are integrated with the insulator Ju, the conductive elastic member CM1 is simultaneously integrated with the bus bar module 10E by insert molding. In such insert molding, the molten resin of the insulator Ju penetrates into the holes in the conductive elastic member CM1 and is integrated by the anchor effect. This integration makes it possible to prevent the positional deviation between the positive bus bar PB and the conductive elastic member CM1 when a load such as vibration is applied to the battery pack 100E from the outside.

In addition, the conductive elastic member CM1 and the positive bus bar PB, and the negative bus bar NB and the negative electrode N1 are coated with a conductive adhesive. This reduces contact resistance and prevents the formation of an oxide film on the outer surface of the conductive elastic member CM1 and the contact surface of the bus bars. This allows a stable current to flow with constant electrical resistance over a long period of time.

The battery pack 100E of the fourth embodiment described above has the same effect as the battery pack 100A of the second embodiment. In the battery pack 100E of the fourth embodiment, the conductive elastic member CM1 is disposed between the positive electrode Btp and the bus bar module 10E in the orthogonal direction CD. The conductive elastic member CM1 has a fifth contact portion that contacts the positive electrode Btp in the orthogonal direction CD and a sixth contact portion that contacts the positive electrode bus bar in the orthogonal direction CD. Even if there is variation in the position and dimensions between the batteries Bt, the conductive elastic member CM1 interposed between the positive electrode bus bar PB and the positive electrode Btp in the orthogonal direction CD follows the shape of the positive electrode Btp side to absorb such variation. In other words, the conductive elastic member CM1 functions like a sponge or cushion. Therefore, the variation in the position and dimensions of the batteries Bt is absorbed, and the decrease in conductivity is suppressed.

In addition, in the battery pack 100E of the fourth embodiment, the conductive elastic member CM1 further has a seventh contact portion that contacts the insulator Ju in the orthogonal direction CD and contacts the battery Btc2A in the axial direction AD, and an eighth contact portion that contacts the positive bus bar PB in the axial direction AD. This increases the contact cross-sectional area between the conductive elastic member CM1 and the positive bus bar PB, thereby further improving conductivity. In addition, the conductive elastic member CM1 has a shape that sits well and is easy to manufacture.

E. Fifth embodiment:
E1. Overview of battery pack configuration:
Fig. 13 is a cross-sectional view for explaining a battery pack 100F of the fifth embodiment. As shown in Fig. 13, the battery pack 100F of the fifth embodiment is different from the battery pack 100B of the third embodiment in that it includes a conductive elastic member CM2. Other than this, the configuration of the battery pack 100F of the fifth embodiment is the same as the configuration of the battery pack 100B of the third embodiment, so the same components are denoted by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 13, the conductive elastic member CM2 has a ninth contact portion Rc9 that contacts the positive electrode Btp in the axial direction AD. The conductive elastic member CM2 is sandwiched between the positive electrode bus bar PB and the positive electrode Btp in the axial direction, but has a thin, disk-like external shape. The positive electrode bus bar PB contacts the positive electrode Btp in the orthogonal direction CD. In addition, the positive electrode bus bar PB contacts the conductive elastic member CM2 in the axial direction AD and the orthogonal direction CD. As described above, the conductive elastic member CM2 has a ninth contact portion Rc9 that contacts the positive electrode Btp in the axial direction AD, so that even if there is variation in the position and dimensions of the battery Btc2A, the conductive elastic member CM2 absorbs the variation in the axial direction AD and suppresses the decrease in conductivity. In addition, the region of the positive electrode bus bar PB that faces the positive electrode Btp in the axial direction AD is thinner in the axial direction AD than the battery pack 100B of the third embodiment. Because the conductive elastic member CM2 is disposed in the gap region resulting from this thinning, the height in the axial direction AD of the busbar module 10F is the same as the height in the axial direction AD of the busbar module 10B in the third embodiment. Therefore, even if the conductive elastic member CM2 is disposed in the axial direction of the positive electrode Btp, the thickness of the busbar module 10F remains the same as that of the busbar module 10B in the third embodiment, and the increase in size of the battery pack 100F is suppressed.

Furthermore, the pressing plate portion Ue presses the positive busbar PB and the conductive elastic member CM2 against the positive electrode Btp in the region of the end face in the axial direction AD of the positive electrode busbar PB that faces the conductive elastic member CM2 and the positive electrode Btp, so that the above-mentioned variation in the axial direction AD is absorbed and the conductivity between the positive electrode busbar PB and the positive electrode Btp is further improved.

The battery pack 100F of the fifth embodiment described above has the same effect as the battery pack 100B of the third embodiment. In the battery pack 100F of the fifth embodiment, the conductive elastic member CM2 has a ninth contact portion Rc9 that contacts the positive electrode Btp in the axial direction AD. The positive electrode bus bar PB contacts the positive electrode Btp in the orthogonal direction CD, and contacts the conductive elastic member CM2 in the axial direction AD and the orthogonal direction CD. As described above, the conductive elastic member CM2 has a ninth contact portion Rc9 that contacts the positive electrode Btp in the axial direction AD, so that even if there is variation in the position and dimensions of the battery Btc2A, the conductive elastic member CM2 absorbs the variation in the axial direction AD, thereby suppressing a decrease in conductivity. Furthermore, even if the conductive elastic member CM2 is arranged in the axial direction of the positive electrode Btp, the thickness of the positive electrode bus bar PB is thin in the axial direction AD in this arrangement area, so the thickness of the bus bar module 10F is the same as the thickness of the bus bar module 10B of the third embodiment. This prevents the battery pack 100F from becoming larger.

F. Other embodiments:
(F1) In the above embodiment, the negative bus bar NB has an insulator Ju in contact with it in the axial direction, but the present disclosure is not limited to this. The negative bus bar NB may or may not have an insulator Ju in contact with it in the axial direction. In other words, the bus bar module 10 may not have the second two-layer structure portion 22S or the third two-layer structure portion 23S in which the insulator Ju and the negative bus bar are adjacent to each other in the axial direction. In other words, the negative bus bar NB may have a single-layer structure over the entire orthogonal direction.

(F2) FIG. 14 is a schematic diagram for explaining the pressing load adjustment member Pu attached to the pressing plate portion Ue2 in the battery pack 100C of another embodiment (F2). In the battery pack 100C of the other embodiment (F2), the pressing plate portion Ue2 differs from the battery pack 100B of the third embodiment in that it has a two-layer structure. As shown in FIG. 14, the pressing plate portion Ue2 has a two-layer structure of a first layer Ue1 and a second layer UeA in the axial direction. The first layer Ue1 is formed of an aluminum plate. Note that the first layer Ue1 is not limited to aluminum, and may be formed of any other type of metal plate, as long as the effect of this embodiment is achieved. The second layer UeA is formed of a glass fiber-reinforced PBT (polybutylene terephthalate) plate. Note that the second layer UeA is not limited to glass fiber-reinforced PBT, and may be formed of any other type of resin plate, as long as the effect of this embodiment is achieved. The first layer Ue1 and the second layer UeA are integrated by insert molding. A large number of pressing load adjustment members Pu are press-fitted into holes provided in the second layer UeA. As shown in FIG. 14, a large number of pressing load adjustment members Pu are independent of each other. As with the battery pack 100A of the second embodiment, the pressing load adjustment member Pu is made of an elastic body, for example, made of rubber such as EPDM. Note that the pressing load adjustment member Pu is not limited to rubber such as EPDM, and may be made of an elastic body of any other type of material as long as it achieves the effects of this embodiment. The first layer Ue1 is made of a metal plate, so that rigidity is ensured, and the second layer UeA is made of a resin plate, so that insulation is ensured. In addition, since both the second layer UeA and the pressing load adjustment member Pu are made of resin, they fit well together and deformation due to differences in materials is suppressed.

(F3) FIG. 15 is a schematic diagram for explaining the pressing load adjustment member PuB attached to the pressing plate portion Ue2 in the battery pack 100D of another embodiment (F3). The battery pack 100D of another embodiment (F3) differs from the battery pack 100C of another embodiment (F2) in that a large number of pressing load adjustment members PuB are connected to each other. The battery pack 100D of another embodiment (F3) has the same effect as the battery pack 100C of the other embodiment (F2). In addition, as shown in FIG. 15, a large number of pressing load adjustment members PuB of the battery pack 100D are connected to each other. In the region where they are connected to each other, the pressing load adjustment member PuB and the end face of the second layer UeA are in contact with each other in the axial direction. Therefore, the contact area between the pressing load adjustment member PuB and the pressing plate portion Ue2 in the orthogonal direction CD is enlarged, and the bonding strength between them is improved.

(F4) In the above embodiment, the pressing load adjustment members Pu, PuB were pressed into the pressing plate portions Ue, Ue2, but the pressing load adjustment members Pu, PuB and the pressing plate portions Ue, Ue2 may be formed by insert molding.

(F5) In the fourth and fifth embodiments, the conductive elastic members CM1 and CM2 are arranged only at positions in contact with the positive bus bar PB, but the present disclosure is not limited to this. If the conductive elastic members CM1 and CM2 arranged only at positions in contact with the positive bus bar PB are insufficient to absorb the variations in the positions and dimensions of the battery Bt, a conductive elastic member may also be arranged at a position in contact with the negative bus bar NB. In other words, the conductive elastic members CM1 and CM2 may be arranged at a position in contact with the negative bus bar NB in addition to a position in contact with the positive bus bar PB. Furthermore, the conductive elastic members CM1 and CM2 may be arranged only at a position in contact with the negative bus bar NB.

(F6) In the battery pack 100E of the fourth embodiment, the pressing plate portion Ue and the pressing load adjustment member Pu are provided, but they may be omitted. The positive electrode Btp and the positive electrode bus bar PB may be connected by wire bonding using wiring.

(F7) In the battery pack 100E of the fourth embodiment described above, the conductive elastic member CM1 has the fifth contact portion Rc5, the sixth contact portion Rc6, the seventh contact portion Rc7, and the eighth contact portion Rc8, but it does not have to have the seventh contact portion Rc7 and the eighth contact portion Rc8. In other words, there may be no portion of the conductive elastic member CM1 that is parallel to the positive bus bar PB in the perpendicular direction CD.

(F8) In the battery pack 100F of the fifth embodiment described above, only the conductive elastic member CM2 in contact with the positive electrode Btp in the axial direction AD was arranged, but the conductive elastic member CM1 shown in FIG. 12 may be further arranged. In other words, the conductive elastic member may have a fifth contact portion Rc5, a sixth contact portion Rc6, a seventh contact portion Rc7, an eighth contact portion Rc8, and a ninth contact portion Rc9. In addition, the conductive elastic member may have a fifth contact portion Rc5, a sixth contact portion Rc6, and a ninth contact portion Rc9.

(F9) In the battery pack 100E of the fourth embodiment described above, the conductive elastic member CM1 is integrated with the bus bar module 10E by insert molding, but the integration may be achieved by any other method, such as welding, without being limited to insert molding.

(F10) In the battery pack 100E of the fourth embodiment described above, the conductive elastic member CM1 was formed of a porous elastic member made of metal, but this is not limited thereto, and it may be formed of a porous resin material containing a conductive filler.

(F11) In the battery pack 100E of the fourth embodiment described above, the conductive elastic member CM1 is a member having a greater compression rate than the positive bus bar PB, but the present disclosure is not limited to this. The conductive elastic member CM1 may be a member having a greater compression rate than the negative bus bar NB. The conductive elastic member CM1 may also be a member having a greater compression rate than the positive bus bar PB and the negative bus bar NB. In other words, the conductive elastic member CM1 may be a member having a greater compression rate than at least one of the bus bars.

The present disclosure is not limited to the above-described embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the above-described embodiment that correspond to the technical features in the form described in the Summary of the Invention column can be replaced or combined as appropriate to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

10, 10A, 10B, 10E, 10F...busbar module, 11...busbar, 11S...first single layer structure, 12, 12A, Ju...insulator, 12S...second single layer structure, 20...battery array group, 21S...first two-layer structure, 22S...second two-layer structure, 23S...third two-layer structure, 30...insulating member, 40...lower case, 50...upper case, 100, 100A, 100B, 100C, 100D, 100E, 100F...battery pack, AD...axial direction, Bt, Btc1, Btc1A, Btc2, Btc2 A...battery, BtA...battery set, Btn...negative electrode, Btp, P1...positive electrode, CD...orthogonal direction, CM1, CM2...conductive elastic member, N1...negative electrode, NB...negative electrode bus bar, PB...positive electrode bus bar, Pu, PuB...pressing load adjusting member, R1, R2...vicinity area, Rc1...first contact portion, Rc2...second contact portion, Rc3...third contact portion, Rc4...fourth contact portion, Rc5...fifth contact portion, Rc6...sixth contact portion, Rc7...seventh contact portion, Rc8...eighth contact portion, Rc9...ninth contact portion, TN1...total negative electrode, TP1...total positive electrode, Ue, Ue2...pressure plate, Ue1...first layer, UeA...second layer, Uh...hole, Vt1, Vt2, Vt3, Vt4, Vt5, Vt6, Vt7, Vt8...volts, WB...wiring, dw...spacing

Claims (7)

A battery pack comprising:
A plurality of batteries arranged in an axially aligned manner;
A bus bar module is disposed in a stacked manner in the axial direction with respect to the plurality of batteries and is electrically connected to the plurality of batteries,
a positive electrode bus bar electrically connected to each of the positive electrodes of the plurality of batteries;
a negative electrode bus bar electrically connected to each of the negative electrodes of the plurality of batteries;
an insulator interposed between the positive bus bar and the negative bus bar;
a busbar module having
Equipped with
Each of the plurality of batteries has the positive electrode located at a center portion at an end portion in the axial direction and the negative electrode located at an outer periphery portion at the end portion,
the positive bus bar and the negative bus bar are arranged at a predetermined interval in an orthogonal direction perpendicular to the axial direction so as not to overlap each other in the axial direction,
The positive bus bar contacts the positive electrode at least in the orthogonal direction,
the negative bus bar contacts the negative electrode in the axial direction,
the insulator has a first contact portion that contacts the positive bus bar in the axial direction, a second contact portion that contacts the positive bus bar in the orthogonal direction, and a third contact portion that contacts the negative bus bar in the orthogonal direction,
the bus bar module has a first two-layer structure portion in which the positive bus bar and the insulator overlap in the axial direction, and a single-layer structure portion in which only the insulator is arranged in the axial direction and adjacent to the first two-layer structure portion in the perpendicular direction. 2. The battery pack according to claim 1,
The insulator further includes a fourth contact portion that contacts the negative bus bar in the axial direction,
the bus bar module further includes a second two-layer structure portion adjacent to the one-layer structure portion in the orthogonal direction, the second two-layer structure portion being configured so that the negative bus bar and the insulator overlap in the axial direction. The battery pack according to claim 1 or 2,
the positive electrode bus bar is in contact with the positive electrode in the axial direction in addition to the orthogonal direction. The battery pack according to any one of claims 1 to 3,
The positive electrode and the positive electrode bus bar are connected by wire bonding. 4. The battery pack according to claim 3,
the positive electrode and the positive electrode bus bar are welded in the axial direction. The battery pack according to any one of claims 1 to 5,
the negative electrode and the negative electrode bus bar are electrically connected in the axial direction by welding. The battery pack according to any one of claims 1 to 5,
the negative electrode and the negative electrode bus bar are electrically connected in the axial direction by wire bonding.

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